What Happens in an Overdose of Barbiturates
In this post
Barbiturates are a group of medicines that slow down the activity of the brain and the nervous system. In the past they were widely prescribed for sleep problems and seizures, and they are still used in a small number of medical situations today, under close supervision. The reason they have largely been replaced by other medicines is that the gap between a dose that makes a person sleepy and a dose that can seriously harm them is very small. A person who takes too much, whether by accident, because they have built up tolerance and take more to get the same effect, or because they have mixed barbiturates with another substance, can slip from sleepiness into a state where the body can no longer protect itself. That is an overdose, and it is a medical emergency.
An overdose of barbiturates does not look like a simple deep sleep. Sleep is a state the body can come out of. In an overdose, the brain is pressed down so far that the basic jobs it normally does without thinking — keeping breathing steady, keeping the heart beating strongly, keeping the person able to cough, swallow and wake up — begin to fail. The person cannot simply decide to wake up, and they cannot be woken by shouting or shaking. Their breathing may become slow and shallow, their skin may turn cold and clammy, and their lips may take on a blue colour because the blood is not carrying enough oxygen. This article explains, in plain words, what happens in the body during a barbiturate overdose, why it is so dangerous, and why help must be sought at once. It is general information only, not individual medical advice.
What Barbiturates Do in the Body
To understand an overdose, it helps to understand what barbiturates do in the first place. The brain works through a balance between signals that excite it and signals that calm it down. Barbiturates strengthen the calming signals. They make the brain less active, which is why they were once used to help people sleep and to stop seizures. At a low level, that calming effect can feel like drowsiness, relaxation and a loosening of worry. The person may feel heavy-lidded, slow to think and unsteady on their feet. Those effects are the reason the drugs were prescribed, but they are also the first step on a path that becomes dangerous when the amount in the body rises.
The problem is that barbiturates do not stop at a useful level of calm on their own. As the amount increases, the calming effect deepens, and it begins to affect parts of the brain that control the most basic functions of life. The brain stem, a small area at the base of the brain, controls breathing and helps keep blood pressure steady. When barbiturates press down on this area, breathing becomes slower and shallower, and the heart beats more weakly. The person does not notice this happening, because their awareness has already faded. They are not choosing to breathe less. Their body is simply losing the ability to keep breathing going properly, and there is nothing they can do about it from inside that state.
Tolerance makes this danger worse. A person who uses barbiturates regularly finds that the same amount no longer produces the same sleepiness, because the brain has adapted to the drug. They may take more to reach the effect they are used to, and that larger amount moves closer to the amount that suppresses breathing. Tolerance to the sleepy feeling develops faster than tolerance to the effect on breathing, which means a person can feel that they need a larger dose while their breathing remains just as sensitive to harm. That mismatch is one of the reasons overdoses happen even to people who believe they know their own limits.
How an Overdose Begins
An overdose often begins quietly, and that quietness is part of what makes it so frightening. There may be no sudden collapse and no dramatic moment that tells everyone nearby that something is wrong. Instead, the person becomes more and more drowsy, their speech becomes slurred, and their movements become clumsy. They may stumble, drop things, or seem confused about where they are. Family members sometimes mistake this for drunkenness or simple tiredness, especially if the person has taken the drug before without obvious trouble. But the difference is that in an overdose the drowsiness does not level off. It keeps deepening.
As the level of the drug rises, the person becomes harder to wake. At first they may respond to their name or to a touch on the shoulder. Then they may only respond to a firm shake. Then they may not respond at all, even to shouting or pain. This loss of response is one of the most important warning signs, because it means the brain is no longer able to keep the person aware of the world around them. A person in this state cannot call for help, cannot describe how they feel, and cannot protect their own airway. If they vomit while lying on their back, they may breathe the vomit into their lungs, because the reflexes that normally make a person cough or turn their head are no longer working.
The time it takes for an overdose to develop varies. It depends on how much was taken, whether the person had eaten, whether they had used other substances, and how their body handles the drug. Some people become dangerously ill within an hour, while in others the decline is slower, spread over several hours. That slow decline can be misleading. A person who seems only sleepy at first may be far worse an hour later, even without taking anything more, because the drug is still being absorbed and still building up in the body. That is why waiting to see if things improve is never the right choice. Once the warning signs are there, the situation needs urgent attention.
Breathing Slows Down
The single most dangerous effect of a barbiturate overdose is what it does to breathing. Normal breathing is automatic. You do not have to think about it, and your body adjusts it without your help, breathing faster when you need more oxygen and slower when you are resting. Barbiturates interfere with that automatic control. They tell the brain that less breathing is enough, even when the body is running short of oxygen. The breaths become slower, then shallower, and the gaps between breaths become longer. In a severe overdose, breathing may stop altogether for stretches of time, or stop completely.
When breathing slows, oxygen levels in the blood fall and carbon dioxide builds up. The body needs oxygen for every organ, and the brain is the most sensitive of all. Without enough oxygen, brain cells begin to suffer within minutes. This is why a person in an overdose may develop a blue tinge to the lips, face and fingertips. That blue colour is a visible sign that the blood is not carrying enough oxygen, and it is a sign that should never be ignored. The skin may also become cold and clammy, because the circulation is struggling and the body is under severe stress.
Shallow breathing also makes it harder for the lungs to clear themselves. Normally, coughing and deep breaths keep the airways clear of mucus and anything else that gets in. In an overdose, those defences are weakened. If the person has vomited, fluid can slide into the lungs and cause a serious infection or block the airways. Even without vomiting, the lungs can become congested because the person is lying still for hours, barely breathing, and not moving. This kind of lung damage can continue to cause trouble even after the drug itself has started to wear off, and it is one of the reasons that hospital care is often needed for some time after an overdose.
The Brain Shuts Down
In an overdose, the brain is not simply asleep. It is being suppressed to a level where it cannot do its ordinary work. Thinking, memory, judgement and awareness all fade, and eventually the person loses consciousness completely. They cannot be woken, and they do not respond to the world around them. This state is sometimes called a coma, and it is not the same as sleep. In sleep, the brain is still active in important ways, still listening for danger, still able to wake the person if something goes wrong. In a barbiturate coma, those safety systems are switched off, and the brain cannot wake the person to protect them.
While the person is unconscious, the brain is also being starved of oxygen because of the slow breathing. That combination — a brain that is both suppressed by the drug and short of oxygen — can cause lasting damage. Brain cells are delicate, and they do not recover easily once they have been deprived of oxygen for a long time. The longer the overdose goes on without help, the greater the risk of damage to memory, thinking and movement, even if the person survives. Some people who survive a severe overdose are left with confusion, poor concentration, or problems with coordination that take months to improve, and some of these problems do not fully go away.
Seizures can also occur, and they may seem surprising, because barbiturates are used in medicine to stop seizures. But in an overdose, and particularly as the drug wears off, the brain can become unstable. The calming effect fades unevenly, and the brain can swing from being deeply suppressed to being overexcited. That swing can trigger a seizure, which is a sudden burst of uncontrolled electrical activity in the brain. During a seizure, the person may shake, stiffen, bite their tongue, or stop breathing for a short time. Seizures add to the danger, because they increase the brain’s need for oxygen at the very moment when breathing is already weak.
The Heart and Blood Pressure
Barbiturates also affect the heart and the blood vessels. In an overdose, the heart beats more slowly and less strongly, and blood pressure falls. The pulse may become weak and hard to feel, and at times it may speed up and then fade, as the body struggles to keep blood moving. This matters because every organ depends on a steady flow of blood to bring oxygen and remove waste. When blood pressure falls too low, the kidneys, the liver and the brain all receive less blood than they need, and they begin to suffer.
Low blood pressure also makes the person feel cold. Their hands and feet may become cool, their skin may become pale or mottled, and they may sweat in a cold, clammy way. These are signs that the circulation is failing to keep the body warm and supplied. If the blood pressure falls far enough, the heart itself may begin to fail, because the heart muscle also needs a good blood supply to keep beating. In the most severe overdoses, the heart can stop altogether. This is why an overdose is not only a problem of breathing or of the brain. It is a problem of the whole body losing the systems that keep it alive.
The strain on the heart can also show up as an irregular heartbeat. The heart normally beats in a steady rhythm, but when the blood is low in oxygen and the body’s chemistry is disturbed, that rhythm can become uneven. An irregular heartbeat makes the circulation even less effective, because the heart is not pumping properly with each beat. The combination of a slow, weak pulse and an irregular rhythm is a sign of a body in serious trouble, and it needs hospital monitoring, because it can worsen suddenly even after the person seems stable.
Vomiting, Cold Skin and Other Warning Signs
There are several warning signs that people around a person in overdose may notice before the situation becomes critical. Confusion is one of the earliest. The person may speak in a muddled way, repeat themselves, or seem unsure of where they are. Their coordination may be poor. They may stagger, bump into furniture, or be unable to hold a cup steadily. Their pupils — the black centres of the eyes — may become small or react slowly to light, although this sign varies and should not be relied on alone.
Vomiting is another common sign, and it is particularly dangerous in this situation. A person who is awake and alert can turn their head and cough if they vomit, which protects the airway. A person who is heavily sedated cannot do that. Vomit can slide into the lungs, block the airway, and cause choking or a severe lung infection. If someone who has taken barbiturates is vomiting and becoming drowsy, they should never be left lying on their back alone. They need help at once, and they need to be kept safe until that help arrives.
Cold, clammy skin, slow breathing, a weak pulse, a blue tinge to the lips, and no response to shouting are all signs that the overdose has become severe. None of these signs should be waited out. They do not mean the person is sleeping it off. They mean the body is failing, and that the next stage, without help, is likely to be worse. The safest response is to call emergency services immediately, to describe what has happened as clearly as possible, and to stay with the person until help arrives. In many places, the emergency services would rather be called too early than too late, and an early call can make the difference between survival and death.
Why Mixing Makes It Worse
Barbiturate overdoses become far more dangerous when another substance that also slows the brain is involved. Alcohol is the most common example. Alcohol, like barbiturates, calms the brain and slows breathing. When the two are taken together, their effects do not simply add up. They multiply each other, so that a dose of barbiturates that might have been survivable on its own can become fatal when alcohol is present. The same is true of other sedatives, sleeping medicines, and some pain medicines that also slow breathing. A person who mixes these substances may not realise how much more dangerous the combination is, because each one on its own may have felt manageable before.
Mixing also makes it harder for the people around the person, and for the doctors treating them, to know what has happened. The symptoms of different sedatives overlap, and the person cannot explain what they took or how much. That uncertainty can delay the right care, because the medical team has to work out what is in the body before they can treat it properly. It is always better to tell the emergency services and the hospital honestly what was taken, including alcohol and any other medicines, because that information helps them give the right treatment quickly. There is no benefit in hiding it, and the risk of hiding it can be very high.
Another danger of mixing is that it makes the overdose last longer. The body clears barbiturates slowly, and alcohol and other substances can slow that clearing further. That means the person may remain unconscious and at risk for many hours, even a day or more, rather than waking up after a few hours. During that long period, they need careful monitoring of breathing, blood pressure and oxygen, and they may need support to keep their airway open and their lungs clear. A long overdose is not a sign that the situation is stable. It is a sign that the body is under prolonged strain, and that strain can cause damage to the brain, the lungs and the kidneys even after the drug has begun to wear off.
What Happens Afterwards for Survivors
Surviving a barbiturate overdose does not always mean returning to full health at once. Some people wake up after hours of unconsciousness feeling confused, weak and unsteady, with a poor memory of what happened. That confusion can last for days, as the drug slowly leaves the body and the brain recovers from being suppressed and short of oxygen. Thinking may be slow, concentration may be poor, and the person may feel exhausted even after sleeping for a long time. These are signs that the brain is still recovering, and they usually improve gradually, but they can be frightening for the person and for their family.
The lungs often need time to recover as well. If vomit or fluid entered the lungs during the overdose, the person may develop a chest infection that needs treatment. They may cough, feel short of breath, or have a fever for days after the event. The kidneys can also be affected, because low blood pressure during the overdose reduces the blood flow to them, and because a person lying still for many hours can damage muscles, which then release substances that strain the kidneys. Hospital care after an overdose is therefore not only about waiting for the drug to wear off. It is about watching for these complications and treating them before they become serious.
For many people, surviving an overdose is a turning point. It is a stark reminder of how close the body came to failing, and it can be the moment when a person decides to seek help for their use of barbiturates. That help exists, and it works best when it is sought early, before another overdose happens. Stopping barbiturates suddenly on one’s own can itself be dangerous, because the brain has adapted to the drug and can react badly when it is removed too quickly, so any decision to stop should be discussed with a health professional who can plan a safe way to do it. The aim is not only to survive one overdose, but to avoid the next one, and that takes support, planning and time.
Getting Help in Time
When a barbiturate overdose is suspected, time matters more than almost anything else. The sooner help arrives, the sooner breathing and circulation can be supported, and the less time the brain spends without enough oxygen. Calling emergency services is the first and most important step, and it should be done as soon as the warning signs appear, rather than after waiting to see whether the person improves. A person who is hard to wake, who is breathing slowly, or whose lips have turned blue is already in serious danger, even if they were only sleepy a short time earlier. Emergency services are used to these calls, and they would far rather be called early than arrive after the situation has become worse.
It helps to be able to tell the people on the phone what has happened, as clearly as possible. That means saying what the person is believed to have taken, how much if it is known, when it was taken, and whether alcohol or any other medicine was involved. It also means describing what the person looks like now: whether they are breathing, whether they respond to their name, and whether they have vomited. This information is not collected out of curiosity. It helps the emergency team prepare, and it helps the hospital give the right care when the person arrives. If the medicine packaging is nearby, keeping it to show the medical team can also help, because it tells them exactly which drug is involved.
While waiting for help, the most useful thing a person nearby can do is stay with the person who is ill and keep them safe. They should not be left alone, and they should not be given food or drink, because they may not be able to swallow properly. If they vomit, they need to be kept from breathing it into their lungs, and the safest position for an unconscious person is normally on their side, so that fluid can drain from the mouth rather than sliding into the airway. These are general points, not a substitute for the advice of the emergency services on the phone, who can talk a caller through what to do while help is on its way. The key point is simple: do not leave the person, do not wait, and do not assume they will wake up on their own.
My Take:
What strikes me most about a barbiturate overdose is how quiet it is. There is no loud alarm in the body to warn that breathing is failing. The person simply becomes sleepier, then quieter, then still, and the people around them may not realise how serious the situation has become until it is very serious indeed. I think that quietness is the most dangerous thing about these drugs. A heart attack is frightening because it announces itself with pain. An overdose of barbiturates can look like someone who has simply fallen asleep, and that appearance can cost precious time. If there is one idea I would want every reader to take from this article, it is that a person who cannot be woken is not sleeping. They are in danger, and they need help at once.
I also think about the small gap between a dose that helps and a dose that harms, because that gap explains so much of the history of barbiturates. These were medicines that doctors prescribed with good intentions, for people who could not sleep or who had seizures. But the margin for error was so narrow that a mistake, a bad night, or a drink taken alongside the medicine could turn a treatment into a tragedy. That is why doctors today prefer medicines with a wider margin of safety. It is not that barbiturates were useless. It is that the price of a mistake was too high, and too many people paid it. I find that a sobering lesson about any substance that works on the brain: the same power that makes it useful can make it lethal.
Tolerance is the part of the story that I find hardest to explain to people who have never experienced it, because it sounds like a choice when it is not. A person does not decide to need more of a drug. Their brain changes, quietly, over weeks and months, until the amount that once made them sleepy barely affects them. They take more because the smaller amount no longer works, and they believe they are being careful because they have taken that amount before. But their breathing has not developed the same tolerance, and that mismatch is a trap. I think understanding that trap is important, because it replaces blame with understanding. The person is not being reckless in the way people imagine. They are caught in a process they cannot see, and that process is moving them closer to harm.
The role of alcohol in these overdoses deserves to be said plainly. Alcohol and barbiturates both slow the brain, and together they are far more dangerous than either one alone. I know that many people take a drink to help them sleep, or take a sleeping medicine after a drink, without thinking of it as a dangerous combination. It is dangerous, and it has killed people who believed they were being careful. If a reader takes any medicine that causes sleepiness, I would ask them to think very carefully about alcohol, and to talk to a health professional about the combination. A single evening of mixing the two can be enough to cause harm that cannot be undone.
I think a lot about the people who are there when an overdose happens, because they are the ones who have to make the decision to call for help. That decision can feel difficult. People worry about getting someone into trouble, about overreacting, or about what the neighbours will think. I want to say clearly that none of those worries matter as much as a life. Emergency services exist for exactly this situation, and they would rather arrive to find a person who is recovering than arrive too late. If you are ever with someone who has become unresponsive after taking barbiturates, or any sedative, call for help immediately and stay with them. That call may be the most important thing you ever do.
There is also something I want to say to people who have survived an overdose. Surviving does not make the experience unimportant, and it does not mean the danger has passed. Many people feel embarrassed or ashamed afterwards, and that shame can stop them from talking about what happened or seeking help. I think that is understandable, but I also think it is a mistake to let shame win. An overdose is a sign that something has gone badly wrong with the way a substance is being used, and it is a sign that help is needed. Asking for that help is not a confession of failure. It is a practical step, the same as going to a doctor after a bad fall. The body gave a warning. The wise response is to listen to it.
Stopping barbiturates is not something a person should attempt alone, and I want to be honest about why. The brain adapts to these drugs, and when they are removed suddenly, the brain can rebound in a dangerous way. That rebound can cause confusion, severe anxiety, tremors and seizures, which are themselves medical emergencies. I know that sounds frightening, and it is meant to be taken seriously, but it is not a reason to give up on stopping. It is a reason to stop with proper help. A health professional can plan a gradual reduction, monitor the person, and give support through the difficult days. That plan is slower than simply throwing the tablets away, but it is far safer, and safety is what matters here.
I think about families a great deal when I write about overdoses, because families are the ones who live with the fear and the aftermath. A parent who finds their child unresponsive, a partner who watches someone they love slip away, a friend who wonders whether they should have called sooner — these are experiences that stay with people for years. If you are a family member reading this, I would say that your worry is not an overreaction. If someone you love uses barbiturates, talk to them about the risks, keep the number for emergency services close at hand, and talk to a health professional yourself about what to do in an emergency. You cannot control another person’s choices, but you can be ready, and being ready can save a life.
One thing that gives me hope is that these tragedies are preventable. Barbiturates are prescribed far less often than they once were, and doctors are far more aware of the risks of mixing them with alcohol and other sedatives. Public understanding has also improved, and more people now know that an unresponsive person needs urgent help rather than being left to sleep it off. That knowledge saves lives, and every article that spreads it is worth writing. If this article helps even one person recognise the signs of an overdose a little earlier, or make the call a little sooner, then it has done its job.
I also want to be direct about the value of a life that feels ordinary. The people who die from barbiturate overdoses are not statistics. They are parents, children, partners and friends, and their deaths leave holes that cannot be filled. The same is true of the people who survive with lasting damage to their brain or their lungs. Their lives become harder in ways that are not always visible, and they carry that harm with them every day. I think that is worth remembering when the subject feels abstract. Behind every fact about breathing and blood pressure, there is a person whose life mattered, and whose story deserved a different ending. The best way to honour that is to understand the danger, to respect it, and to act quickly when it appears.
Sharing medicines is another danger I want to mention, because it is more common than people admit. A person who has trouble sleeping may be offered a tablet by a friend or a family member who was prescribed it for a different reason. That tablet may seem harmless because it helped the other person, but a medicine that is safe for one person, at one dose, under a doctor’s care, can be dangerous for another person, especially if that person has also had a drink, or is taking another medicine, or has a health problem the giver knows nothing about. I think medicines should never be shared, and I think that rule is worth repeating to young people in particular, who may be offered tablets at a party or in a hostel without understanding what they are taking.
I also think about the hours in hospital after an overdose, because they are often the part of the story that nobody talks about. The person may be unconscious for a long time, connected to machines that watch their breathing and their heart, while their family waits outside with very little information. Those hours are frightening, and they are also boring in a strange way, because there is nothing to do but wait. I think that waiting is one of the hardest experiences a family can go through, and it is a reminder that an overdose does not only harm the person who took the drug. It reaches out and touches everyone who loves them, and the worry it causes does not end when the person wakes up. It stays, in the form of a fear that it could happen again.
There is a question I am sometimes asked, which is whether barbiturates are still a problem now that they are prescribed less often. The honest answer is that they are less common than they once were, but they have not disappeared. Old supplies remain in medicine cabinets, they are still prescribed in a small number of situations, and they are still available through other routes. A drug does not need to be fashionable to be dangerous. It only needs to be in someone’s home, in a drawer, at a moment when they are struggling to sleep or feeling desperate. That is why I think this article still matters, and why I think the information in it should be known widely, not only by doctors but by ordinary people.
I want to say something about young people, because they are the ones who are most likely to be offered a tablet without understanding what it is. A teenager who is told that a pill will help them sleep, or help them relax, may not know that it is a barbiturate, or that it can stop their breathing. They may trust the person who offers it, and they may not ask questions. I think the best protection for young people is honest information, given early, before they are in a situation where they have to decide. Tell them that some sleeping tablets can be lethal, that mixing them with alcohol is far more dangerous, and that a friend who cannot be woken needs help at once. That knowledge, given calmly and without lectures, can save a life.
I also think about the people who work in medicine, and how much they have learned about overdoses over the years. Hospital care for an overdose is far better now than it was fifty years ago. Breathing can be supported, blood pressure can be monitored, and complications can be treated as they appear. That progress is real, and it means that many people who would once have died now survive. But it has a limit. No amount of hospital care can undo the minutes when the brain was starved of oxygen before help arrived. That is why the most important part of the story is still the earliest part: recognising the signs, calling for help, and staying with the person. The hospital can do a great deal, but it cannot turn back time.
There is one more thing I want to say, and it is about the days and weeks after a person comes home from hospital. Surviving is not the same as being well again. The person may feel weak, confused, or frightened, and they may struggle with the memory of what happened. Their family may feel relieved and angry at the same time, and those feelings can be hard to talk about. I think that period deserves patience from everyone involved. Recovery is not only physical. It is emotional, and it takes time. The kindest thing a family can do is to be steady, to keep the conversation open, and to help the person get the support they need, without turning the overdose into a subject that can never be mentioned again.
Finally, I would ask readers to remember that prevention is not complicated. Keep medicines in their original packaging, out of reach of children, and never share them with anyone else. If a medicine makes you sleepy, do not drink alcohol with it, and tell your doctor about every other medicine you take. If someone you know uses sedatives, talk to them about the risks, and make sure you know the signs of an overdose and the number for emergency services. These are small, ordinary steps, and they do not require money or special knowledge. They only require attention, and attention is something every one of us can give.
Frequently Asked Questions
What are the main side effects of barbiturates on overdose?
The main dangers in an overdose are slow and shallow breathing, loss of consciousness, a weak pulse and falling blood pressure, cold and clammy skin, a blue tinge to the lips, vomiting that can enter the lungs, and seizures as the drug wears off. Breathing failure is the most serious danger, because without enough oxygen the brain can suffer lasting damage within minutes.
How quickly can barbiturates affect overdose?
The effects can begin within an hour, but the decline is sometimes slower, spread over several hours, because the drug is still being absorbed and building up in the body. A person who seems only sleepy at first may be far worse an hour later, which is why waiting to see if things improve is never the right choice.
Can the harm barbiturates causes to overdose be reversed?
Some of the harm can improve once the drug leaves the body and breathing returns to normal, especially if help arrives early. But damage from a long period without enough oxygen, such as harm to memory and thinking or to the lungs from vomit, can last for months or may not fully go away. Early help gives the body the best chance to recover.
Why does barbiturates affect overdose?
Barbiturates strengthen the calming signals in the brain, and in large amounts they press down on the parts of the brain that control breathing, heartbeat and awareness. That is why an overdose affects so many systems at once: the same suppression that makes the person unconscious also slows their breathing and weakens their circulation.
When should someone seek help about barbiturates and overdose?
Help should be sought immediately, by calling emergency services, if a person who has taken barbiturates is hard to wake, is breathing slowly or shallowly, has a blue tinge to the lips, has cold clammy skin, is vomiting while drowsy, or does not respond to shouting or shaking. Do not wait, and do not leave the person alone.
Where can I learn more about barbiturates and overdose?
Start with the links in Sources below: the National Institute on Drug Abuse, the NHS, the World Health Organization and the U.S. Drug Enforcement Administration all cover barbiturates and overdose. For personal questions, a health professional is the right person to ask.
