Drugs 101

The starting point

Most people who try a drug aren’t in crisis. They’re curious, or at a party, or exhausted, or just want one night off from their own head. Plenty of people say no, and that’s a perfectly good answer. But if all you’ve ever heard is “don’t”, then the day you say yes, your information comes from a friend, a forum or a guess.

That isn’t fair on you. Not using is still the safest choice. If you do use drugs, knowing what you’re taking, how much, what with, and what to do if it goes wrong makes you much less likely to be hurt, and you have every right to know it.

This is health information, not legal advice. Drug laws are very different from one country to the next, and so are the services this article mentions. When it names one, it says where it is.

What harm reduction means

This approach is called harm reduction. Harm reduction means meeting you where you are and helping you stay safer, without making you promise anything first. It includes things like sterile needles, a medicine that reverses an overdose, and treatment that doesn’t demand you stop using before you’re allowed any help.

It isn’t a fringe idea. The World Health Organization recommends it, and so does the whole United Nations system.

You might wonder whether talking this way encourages people to use drugs. Where that has been tested, it has not been found. Studies of handing out overdose medicine found no sign that it led to more drug use, and the same is true of needle programs. Where something hasn’t been tested yet, this article says so.

How common this is

If you’ve ever felt like the only one, you aren’t. The United Nations estimates that about one adult in every sixteen worldwide used a drug in the past year.

Most of them don’t have an addiction. UN figures suggest that roughly four in five people who use drugs don’t have what doctors call a drug use disorder, meaning use that has become a problem.

That’s exactly why the practical side matters. Emergencies do not only happen to people with an addiction. A first time, a stronger batch than usual or an unlucky mix can be enough. In Europe, most drug deaths involve more than one substance, which means a lot of them start with a decision that felt small at the time.

How brain cells pass a message on

One drink makes you chatty. A few more and you’re swaying, and the next morning there’s a gap where the walk home should be. A painkiller after an operation takes the edge off, and a drug from the same family can stop someone breathing. It can look as if every drug has its own kind of magic. They don’t. They all work the same basic way, and once you can see it, a lot of the advice in this article makes much more sense.

Your brain runs on nerve cells, called neurons, and each one is wired to many others. Inside a cell, a message travels as a tiny electrical pulse that lasts about a thousandth of a second. But the cells don’t actually touch. Between one and the next there’s a gap, called a synapse, far too small to see under an ordinary microscope.

To get across the gap, the pulse turns into chemistry. The end of the sending cell holds tiny packets of chemical messengers, called neurotransmitters. When the pulse arrives, some of the packets empty into the gap. The messenger drifts across and lands on receptors on the next cell, which are docking spots shaped to fit it, a bit like a key fitting a lock.

Then the message has to be cleared away, or it would keep going. Most messengers are pumped back into the cell that sent them, to be used again, and some are broken down by enzymes. It all takes a split second, and it’s happening billions of times over in your head right now. Every drug in this article works by getting in the middle of that handover, at the packets, the gap, the docking spots or the pumps.

The messengers you’ve heard of

There are dozens of messengers, but a handful explain most of what drugs do. You’ve probably heard some of their names, and some of the myths that come with them.

• Dopamine helps your brain learn what’s worth doing again, and drives motivation and wanting. It’s often called the pleasure chemical, but that isn’t really its job.
• Serotonin does many jobs: mood, yes, but also sleep, appetite, body temperature and digestion (most of your body’s serotonin is actually in your gut, not your brain!). The idea that depression is simply a lack of serotonin hasn’t held up well, although serotonin is still part of the story.
• Noradrenaline, called norepinephrine in the US, keeps you alert and raises your heart rate and blood pressure. It’s a big part of why stimulants are hard on the heart.
• GABA is the brain’s main brake. It calms cells down and makes them less likely to fire.
• Glutamate is the main accelerator. It excites cells, and it’s central to learning and memory.
• Endorphins are the body’s own opioids. They ease pain and bring a sense of comfort (the famous runner’s high, it turns out, may have more to do with the next one on this list!).
• Endocannabinoids are the body’s own cannabis-like messengers. They work backwards: the receiving cell releases them, and they tell the sending cell to send less. They turn the volume down in many circuits at once.

Where a drug acts matters as much as what it acts on. An opioid eases pain in one part of the brain and slows breathing in another. Alcohol slows the cerebellum, which handles balance, so you sway. It slows the hippocampus, which stores new memories, so there are gaps. And it slows the front of the brain, which weighs up consequences, so another drink seems like a great idea.

How a drug gets in the middle

A drug can get into that handover in a few different ways.

• It copies a messenger. Some drugs are shaped enough like a natural messenger to fit its receptor and switch it on. Opioids copy endorphins. THC, the part of cannabis that gets you high, copies the body’s cannabis-like messengers, but only partly: it fits the lock without turning it all the way.
• It makes more messenger pour out. MDMA and amphetamines, including speed and some ADHD medicines, get taken into the sending cell through its recycling pump and make the pump run backwards, pushing messenger out into the gap. MDMA does this mainly with serotonin.
• It stops the messenger being cleared. Cocaine jams the pumps, so dopamine and noradrenaline stay in the gap and keep signaling. Methylphenidate, the ADHD medicine sold as Ritalin or Concerta, mainly works this way too, and so do the common SSRI antidepressants, for serotonin.
• It blocks a receptor. Ketamine plugs the gate on one of glutamate’s receptors, which is part of why the world goes distant and numb. Naloxone sits on the opioid receptor without switching it on and takes the opioid’s place, which is how it reverses an overdose.
• It turns up a signal that’s already there. Benzodiazepines don’t copy GABA. They sit on a second spot on the GABA receptor and make it respond more strongly whenever GABA arrives. Alcohol does something similar, among other things.
• It turns down how much gets sent. Pregabalin and gabapentin work on the sending side and reduce how much messenger is released. Despite the name, they don’t act on GABA receptors at all.

Receptors also come in two broad kinds. Some are gates: when the messenger lands, the gate opens and the cell changes in a split second. GABA and glutamate receptors work like this, and so do the drugs that act on them, such as alcohol, benzodiazepines and ketamine, which change how awake, steady and responsive you are. Others work more like a dimmer switch. They set off a chain of steps inside the cell that turns a whole circuit up or down, more slowly. Opioids, cannabis and psychedelics act on these, which may be part of why they change mood, pain and perception rather than just making you more or less awake.

The lock and key picture is useful, but it’s a simplification. A key can fit without turning, which is how naloxone works. Some drugs use a second lock on the same door, like benzodiazepines. And the locks themselves change with regular use, which is where tolerance comes from.

Pick a drug in the figure below to see which messenger it works on, how, and the risk that follows. If you pick a downer, you can add a second one and see where the two meet.

Why downers add up

You never have to think about breathing, because a small group of cells in your brainstem, at the base of the brain, keeps the rhythm going for you. Your body also has an alarm that makes you want to breathe, the urge you feel when you’ve held your breath too long.

Opioids act on both. The breathing cells have opioid receptors, and when an opioid lands there, the rhythm slows. Opioids also dull the urge to breathe, so someone can slow right down and stop without gasping or looking distressed. That’s why an overdose can look like deep sleep, snoring and all, which part six explains.

The other downers take different routes to the same place. Alcohol and benzodiazepines turn up GABA, the brake. GHB copies GABA at a different receptor. Pregabalin and gabapentin turn down how much gets sent. Different doors, but they all lead to the same room: the cells that keep you breathing.

Benzodiazepines show this clearly. On their own they rarely stop someone breathing, because they can only boost the GABA that’s already there. Add an opioid or alcohol, and that limit stops protecting you. Each drug pushes on the same circuit from a different side, so “I only had a little of each” doesn’t hold up. The amounts add up in the same place. This is the biology behind the mixing checker in part five.

GHB has a problem of its own. The gap between an amount that feels good and an amount that’s dangerous is small, and there’s no antidote.

Heat, water and a racing heart

Stimulants work on the messengers that keep you alert. Cocaine, amphetamines and MDMA all raise noradrenaline, the same messenger your body uses when you’re frightened or exercising hard. Your heart beats faster, your blood vessels tighten and your blood pressure goes up. That’s why cocaine can strain the heart of someone young and healthy.

How fast a drug reaches the brain matters too. In one study of people who use cocaine, smoked cocaine blocked the dopamine pumps about as much as snorted cocaine did, but the high came on in under two minutes instead of around fifteen, and felt much stronger. The faster the rise, the stronger the pull to do it again, which is part of why smoking or injecting a drug tends to be harder to control than swallowing or snorting it.

MDMA adds two problems of its own, both run by the hypothalamus, a small area deep in the brain that controls body temperature and water. The drug pushes your temperature up, partly through noradrenaline, and in a hot room you can overheat. It also makes the body release a hormone that tells the kidneys to hold on to water. That’s how drinking lots of water on MDMA can drop the salt in your blood low enough for the brain to swell, which is called hyponatremia, and why part three says to sip, not gulp.

Then there’s serotonin. MDMA releases a lot of it at once. If something else stops serotonin being cleared or broken down at the same time, it can build up far beyond what either drug would cause alone. That’s serotonin syndrome: shaking, stiff or twitching muscles, a racing heart, overheating and confusion, and in severe cases it can kill.

The MAOI antidepressants, which stop serotonin being broken down, are the most dangerous partner for MDMA for exactly this reason. Tramadol, a painkiller that also slows serotonin clearing, is another. The common SSRIs mostly do something different with MDMA: they block the pump MDMA needs to get into the cell, which weakens it, and the risk becomes taking more to make up for it.

Why the same amount stops working

Your brain keeps itself in balance. If a drug pushes a system the same way day after day, the brain pushes back. It can make receptors less responsive, pull some of them inside the cell, or turn up the system that works the other way. That push-back is tolerance, and it’s why the same amount does less.

It isn’t as simple as “your receptors are wrecked”. Most of these changes reverse. In one brain-scan study of people who smoked cannabis every day, their cannabis receptors were reduced, and after about four weeks without it they were back to normal.

With opioids there’s an extra trap. Tolerance to the high seems to build faster than tolerance to the effect on breathing. So someone who needs more to feel the same can be closer to an overdose than they realize.

Tolerance also fades, often within days, much faster than most people expect. Your body readjusts, but your sense of what “your usual” is doesn’t change with it. That’s why part seven warns that your usual amount can be too much after a break.

Withdrawal is the same push-back, seen from the other side. When the drug is gone, the brain’s adjustments are still there, with nothing to push against. With alcohol and benzodiazepines, that’s dangerous. Months of a boosted brake leave the brain with its own brake turned down and its accelerator turned up. Take the drug away suddenly and the accelerator runs unopposed, which can cause seizures and, with alcohol, a severe state of confusion called delirium tremens. Stopping alcohol or benzodiazepines suddenly after heavy regular use isn’t a test of willpower. It needs a doctor. The same goes for GHB.

Regular use changes something else too, which is what the brain treats as important. The pull toward a drug can keep growing even as the enjoyment fades. Our article on dopamine explains why.

The day after, and the holes in your brain

A lot of people feel low a few days after taking MDMA, often midweek after a weekend. That dip seems to be real: small studies have found people’s mood dropping a few days after they used it. The usual explanation is that MDMA empties the brain’s serotonin stores for a while. That’s plausible, but it hasn’t been proven, and lost sleep, alcohol and a long weekend probably play a part too. It passes, and it’s one reason drug services suggest leaving a long gap between uses.

You may also have heard that MDMA burns holes in your brain. Part of that story goes back to a 2002 study in monkeys that made headlines around the world. A year later it was retracted: most of the animals had been given methamphetamine instead of MDMA, because of a mislabeled bottle. There’s no good evidence that a night on MDMA leaves holes in anyone’s brain. Heavy, repeated use is linked to small problems with memory and attention, though it’s hard to separate those from other drugs and lost sleep, and animal studies at high doses do show damage to serotonin nerve endings.

Why the same drug can feel so different

You may have noticed this already: the same drug can feel mild one night and overwhelming the next. How it’s taken makes a big difference. Smoked cannabis is felt within minutes, but the same amount eaten can take hours. Strength matters too, and you usually can’t know it. So do your body, your sleep, what you’ve eaten and what else is in your system.

The figure below shows what drug advice services say about each drug, mainly FRANK in the UK and the Alcohol and Drug Foundation in Australia. Pick the one you’re wondering about to see when it usually starts, how long it lasts, its main danger and the step that makes it safer.

The slow ones trip people up

A common mistake has nothing to do with strength. It’s about waiting.

Edibles are the classic example. You eat one, feel nothing after an hour, and start to think it’s a dud, so you take another. Then both kick in at once. If that’s happened to you, it isn’t because you were careless. Eaten cannabis can take up to two hours to start and up to four to peak, which is why the Australian service says to wait at least 4 hours before deciding whether to take more.

Edibles also look like candy. In Canada, more young children ended up in the hospital after eating cannabis by accident once edibles went on sale. If there are any at home, keep them where a child can’t reach.

Pills can be slow too. MDMA can take up to an hour to start, and the same trap applies: the second half of a pill, taken because the first seemed to do nothing, lands on top of it.

Cannabis is stronger than it used to be

If cannabis hits you harder than you remember, you’re not imagining it. It’s much stronger, on average, than it was a few decades ago: THC, the part that gets you high, has gone up, while CBD, which may soften some of its effects, has stayed about the same.

With heavy use, stronger cannabis is linked to a higher risk of psychosispsychosisLosing touch with what is real: hearing or seeing things that are not there, or holding frightening beliefs that other people do not share. Part eight explains who is most at risk., which part eight explains. Canada’s lower-risk guidelines suggest choosing milder products, using only occasionally, and not driving for at least 6 hours afterwards.

The same guidelines say people with a close family history of psychosis should not use it at all. Starting later in life is also safer than starting young.

MDMA: heat, water and the day after

MDMA, also called ecstasy or molly, usually lasts a few hours. The two physical dangers are heat and water.

MDMA makes you hotter, and dancing for hours in a hot room makes you hotter still. The Australian service notes that the risk goes up on warm days, above about 25℃, or 77℉.

Water is where people can go wrong the other way, often while trying to be careful. Drinking too much water on MDMA can be as dangerous as drinking too little. The drug makes the body hold on to water, and the salt in the blood can drop so low that the brain swells. It’s rare, but it has killed people, and women seem to be at higher risk. So sip, don’t gulp! FRANK in the UK says to “sip no more than a pint of water or non-alcoholic drink every hour”.

The day after has its own low. Lots of people feel flat and low for a day or several, which is called a comedown (cue New Order’s Blue Monday). It’s the drug wearing off, not a sign that something is wrong with you. The Australian service suggests leaving one to three months before you use MDMA again.

Cocaine and the heart

Snorted cocaine works within minutes, and the high is short, often around half an hour. That’s part of what makes it hard: the urge to take more comes back fast, and one line can turn into a whole night of them before you’ve really decided anything.

It’s hard on the heart. Even healthy young people can have a seizure, a heart attack or a stroke on it, so “I’m young and fit” doesn’t protect you. Chest pain on cocaine sends many people to the emergency room, and it’s always worth getting checked rather than hoping it passes.

Sharing a straw can pass on infections such as hepatitis C and HIV. Use your own, and not a rolled-up banknote, which can cut the inside of your nose (I know, it’s less cool).

Ketamine: numb, and then some

Ketamine makes you feel detached from your body and your surroundings. Take more and you may not be able to move or speak for a while. People call this a k-hole, and it can be frightening, even if you’ve been before.

Most of the danger comes from the numbness. People hurt themselves without feeling it, fall, or choke if they vomit while they can’t move. The risk is much higher with alcohol or other drugs that slow you down. If a friend on ketamine is asleep or can’t move, put them on their side.

If you use it regularly and it’s started to hurt when you pee, you need to go all the time, or you’ve seen blood, please don’t be embarrassed to see a doctor. It feels like a urine infection that won’t clear, but it’s the bladder being damaged, and it can become serious enough to need surgery. It’s a known problem, and telling them you use ketamine helps them help you. Feeling low for a few days afterwards is also common.

Psychedelics and why the setting matters

LSD and magic mushrooms change how you see, hear and think. LSD can last up to 12 hours, and mushrooms up to around 6. Once it starts, you can’t make it stop early, so where you are and who you’re with matter a lot.

Drug advice services say that having a trip sitter is one of the most effective ways to stay safe on psychedelics. A trip sitter is a friend who stays sober and stays with you. They also advise against taking psychedelics when you’re already feeling low.

A frightening trip isn’t the same as an overdose, and it usually passes as the drug wears off. If a friend is panicking, you don’t need to fix it. Take them somewhere quiet, away from crowds, lights and noise, help them breathe slowly, and stay. A calm voice helps.

Most of the physical danger comes from what people do while tripping, and the deaths linked to LSD are mostly accidents, such as falls or car crashes.

Stronger than people expect

Most of us assume a pill is one dose. It usually isn’t. In Europe, the average ecstasy pill roughly doubled in strength between 2011 and 2019, and much stronger ones are still around. A UK drug-checking charity puts it simply: “A single pill is likely to be more than a single dose.“

What a pill looks like tells you almost nothing. Two pills with the same logo can be completely different in strength and content. Online reports about a logo don’t help either, because your pill may not be the one someone else tested.

In Europe, most ecstasy that gets tested turns out to be pure MDMA. The bigger danger now is strength, not what it was cut with. A pure pill can still be far too strong.

That’s why the drug advice services all say the same thing: start low and wait. FRANK suggests taking “half or even a quarter of the pill” and waiting for it to kick in before taking any more. UK and Australian services suggest waiting at least 90 minutes to two hours before taking more.

You won’t find doses in this article, and that’s on purpose. With street drugs, nobody really knows what’s in them or how strong they are, so a number would only give you false confidence. The safest amount is always less than you think, and waiting is the rule.

It can feel awkward to take less than your friends, or to wait while they don’t. That’s fine. Taking too little is a much easier mistake to live with than taking too much!

Fake medicines look real

Fake medicines are a growing danger, and they’re very convincing. They look exactly like real painkillers, anxiety pills such as Xanax, or ADHD pills such as Adderall, but they can contain something much stronger.

Because they look real, they feel safe, and that’s the trap. The US Drug Enforcement Administration warns: “Never trust your own eyes to determine if a pill is legitimate.”

So treat it this way: a medicine that didn’t come from a pharmacy, with your name on the label, is an unknown drug, however familiar it looks. That includes pills bought online and pills from a friend who swears they’re real, even a friend you trust.

Fentanyl and the new synthetic opioids

Fentanyl is a lab-made opioid, much stronger than heroin. In North America it now turns up in heroin, in fake pills and sometimes in other drugs, and in parts of the US and Canada it is often mixed with animal sedatives such as xylazine or medetomidine. Naloxone doesn’t reverse those sedatives, but give it anyway, because the opioid is almost always there too. In Europe a newer group, the nitazenes, is spreading, and some are hundreds of times stronger than heroin.

The risk is greatest for people who don’t normally take opioidsopioidsA family of drugs that relieve pain and slow breathing, including heroin, fentanyl and painkillers such as codeine, tramadol and oxycodone. Too much can stop someone breathing., because their bodies have no tolerance at all. A line of cocaine or a pill with a hidden opioid in it can stop someone breathing, even if they’ve taken the same thing before without a problem.

Testing your drugs: what it can and cannot tell you

Drug checking means handing a small sample to a service that tests what’s in it, and often how strong it is. Some countries have these services and many don’t, so it’s worth finding out what exists where you live.

A test only helps if you act on it. In studies, an unexpected or dangerous result changes what many people do, but not everyone throws the drug away. It’s understandable, because you’ve paid for it and your friends are waiting, but a bad result is exactly the moment to listen.

Fentanyl test strips are small paper strips, mostly available in North America, that show whether a sample contains fentanyl. They’re cheap, quick and accurate in the lab. But they can give false alarms, they miss some types of fentanyl, and nitazenes need separate strips of their own, which also miss some. No study has yet shown that the strips prevent overdoses.

A test can tell you to be more careful. It can never tell you that something is safe.

Most emergencies involve more than one thing

Picture a long night: a few drinks at dinner, something at the party, and at three in the morning a pill that someone says will help you sleep. None of it feels like a big decision. Each one alone might have been fine. Together, they can stop someone breathing.

This pattern is behind a large share of drug deaths. It’s also one of the easiest things to change, because it doesn’t depend on what’s in the drug. It depends on what you take together. The figure below lets you check two drugs against each other. If a pair isn’t on it, that doesn’t mean it’s safe.

Downers together: the most dangerous mix

The single biggest danger in this article is taking two or more drugs that slow the body down. These include opioids, benzodiazepines such as Xanax or Valium, alcohol, GHB, and the nerve-pain medicines pregabalin and gabapentin. Each one slows your breathing. Together, the effect adds up, and sometimes more than adds up.

With opioids and benzodiazepines, the risk is highest when the combination is new, in the first days of taking them together.

Pregabalin and gabapentin are easy to overlook because they’re ordinary prescription medicines, and alcohol is easy to overlook because it’s legal. All three belong on this list. If you’ve been drinking, the pill that “helps you sleep” is the one to skip.

Uppers together, and uppers with alcohol

Taking two stimulantsstimulantsDrugs that speed the body and mind up, raising heart rate and alertness. Cocaine, MDMA, amphetamines and ADHD medicines are all stimulants. together, such as cocaine with MDMA or speed, puts extra strain on the heart and makes anxiety and paranoia more likely.

Cocaine and alcohol are a very common mix, and you’ve probably seen why: cocaine makes you feel less drunk than you are, so people drink more. The two also combine in the body into a new substance, cocaethylene, which lasts longer than cocaine. You may read that it’s many times more toxic. The research is less certain than that, but the advice to avoid the combination still stands.

Cocaine with an opioid, called a speedball, is dangerous in a quieter way. The cocaine hides how sedated someone is. When it wears off first, the opioid is still working, and breathing can slow or stop.

Antidepressants, lithium and other medicines

If you take a prescribed medicine, you might be worried about how it mixes with a night out. That’s a sensible worry, and the answer depends on which medicine.

The most common antidepressants, the SSRIs, mostly weaken the effect of MDMA. The danger is taking more to chase a high that isn’t coming. An older type of antidepressant, the MAOIs, is genuinely dangerous with MDMA, and people have died. They stay in the body for up to two weeks after you stop.

Tramadol, a prescription painkiller, can cause seizures, and the risk goes up with MDMA, cocaine or antidepressants. Lithium, used for bipolar disorder, has been linked to seizures with LSD or magic mushrooms.

If you take any regular medicine, a pharmacist can tell you how it interacts with other drugs, and it’s an ordinary question to ask. Please don’t stop your own medicine to make room for a night out.

This is not about your own prescription

This part is about taking medicine that was meant for someone else, or taking your own in a different way from how you were told. It’s not about taking your own medicine the way your doctor intended. If your treatment for ADHD, anxiety or pain works for you, nothing here is a reason to stop, and any questions about it belong with your doctor.

Prescription pills feel safer than street drugs. In one way they are, because a real medicine contains what the label says. But that safety depends on who takes it, how much, and with what. It doesn’t travel with the pill.

Someone else’s ADHD medicine

Exam week, too much to do, and a friend offers you one of their ADHD pills. It’s easy to see why you’d say yes. The evidence is disappointing, though. In healthy people the boost is small at best, and in one US study, students who used them didn’t get better grades.

The costs are more reliable. These pills raise your heart rate and blood pressure, and they make it hard to sleep. The person they were prescribed for was checked for heart problems first, and you weren’t. In the US, fakes sold online have been found to contain meth or fentanyl.

If you take them anyway, start with a small amount, don’t mix them with alcohol, and tell someone what you’ve taken. And if you’re this stretched, the pressure deserves attention as much as the pill does. Our article on sleep explains why an all-nighter is such a questionable strategy in the first place.

Benzodiazepines

Benzodiazepines, such as Valium and Xanax, calm anxiety and help with sleep. If you’ve ever been prescribed one during a hard time, you’ll know how much relief they can bring. They’re useful medicines in the short term, but they carry two risks many people don’t know about.

The first is dependence, which can start within days to weeks, even when you take them exactly as prescribed. That isn’t a personal failing. It’s how these medicines work. The second follows from it: stopping suddenly after regular use can cause seizures, which can be life-threatening. If you’ve been taking them regularly, you should come off slowly, with a doctor’s help.

Benzos bought outside a pharmacy are a different problem. Their strength is unpredictable, and some fake ones now contain nitazenes. FRANK’s advice, if you take a street benzo anyway, is to “try a small amount (half a pill) of it first and wait at least an hour”. With opioids or alcohol, they’re part of the most dangerous mix in part five.

Opioid painkillers

Leftover painkillers from an operation, or a few from a relative’s cabinet, can seem harmless because they came from a doctor. Codeine, tramadol and oxycodone relieve pain and make people relaxed and sleepy. They carry the same overdose risk as other opioids, especially if you’ve never taken them before.

Some painkillers mix codeine with paracetamol, which Americans call acetaminophen, or with ibuprofen or aspirin. Taking extra to feel more of the codeine means taking extra of the other painkiller too, which can poison you. The ordinary painkiller becomes the dangerous part.

If you’ve been on an opioid painkiller for weeks, talk to your prescriber before stopping. And leftover medicine is safest out of the house: in the US, take-back programs collect it.

After a break, your usual amount can be too much

Tolerance is how your body gets used to a drug, so the same amount does less. It builds up with regular use, and it drops surprisingly fast when you stop, often within days.

That makes the weeks after a break the most dangerous time of all, and it’s cruel timing, because it’s often when someone has been working hard to change. The risk of dying is much higher in the first weeks after leaving prison, after detox, or after stopping treatment with methadone or buprenorphine. With opioids especially, the amount you used to take can now be enough to kill you. Going back after a break is no reason for shame, but it does need care.

Comedowns, anxiety and low mood

The day after can be hard. After MDMA, cocaine or ketamine, it’s common to feel low, anxious or on edge for a day or a few days. Knowing that a low is the drug wearing off, and not the truth about your life, can make it easier to wait out. Be gentle with yourself while it passes.

Pay attention if the low lasts longer than a comedown should, keeps coming back, or if you find yourself using again to get out of it.

Low mood after using can make everything feel worse than it is. If you’re having thoughts of harming yourself, please tell someone rather than carrying them alone. Our article on suicidal thoughts says where to find someone to talk to, wherever you are.

Psychosis, and who should be most careful

Psychosis means losing touch with what is real: hearing or seeing things that aren’t there, or believing frightening things other people don’t. It’s terrifying to go through, and just as frightening to watch in a friend. Several drugs can trigger it. For most people it passes as the drug wears off. For a smaller number it doesn’t.

Cannabis has the clearest evidence. People who use strong cannabis every day are several times more likely to develop psychosis than people who never use it. The risk is highest with heavy use of strong cannabis, started young, and in young men. The research can’t fully prove cause and effect, but it keeps pointing the same way.

LSD and mushrooms can trigger psychosis in people who are already vulnerable to it. That’s why research trials leave out anyone with a personal or family history of psychosis.

So be most careful if psychosis, schizophrenia or bipolar disorder runs in your family, and if you’re young. If you hear or see things that don’t go away, or feel paranoid for days after using, see a doctor promptly. A first episode is worth following up, even if it fades, and getting help early is nothing to be ashamed of.

Using to cope

Maybe it started as fun, and somewhere along the way it became the thing that gets you through. You might use it to take the edge off stress, to stop thinking for a while, or just to feel nothing for a night. If that’s you, there’s nothing strange about it. About one in five people with depression or anxiety use alcohol or drugs to cope.

It works in the moment, and that’s the trouble. Over time, drugs can make anxiety and low mood worse, and that often eases once the drug use stops. The relief becomes the reason to use, and the reason keeps growing. Our article on dopamine explains that shift, from using for pleasure to using for relief, and why knowing it’s bad for you doesn’t stop the wanting.

If this sounds familiar, you do not need to stop before getting help for how you feel. International treatment guidelines say help for anxiety or depression should never wait until someone has stopped using. You can bring all of it, the using and the reasons, into the same conversation.

When use becomes a problem

Using a drug often is not the same as having a problem with it. The World Health Organization says so plainly: frequent or even daily use does not automatically mean dependence.

What marks a problem is a change in your relationship with the drug. You use more, or for longer, than you meant to. You try to cut down and don’t manage it. You give up things you used to care about, or carry on even though it’s hurting your health, your work or the people you love. You need more to get the same effect, and you feel unwell when you stop.

If you’re asking yourself the question at all, that’s worth listening to. The check below turns those signs into eleven plain questions, based on the ones doctors use. Nothing you tick is saved or sent anywhere. It’s not a diagnosis. It’s there to help you see the pattern and find the right kind of help.