What Drugs Can You Overdose On?

Many drugs can cause an overdose, including illegal substances, prescription medications, over-the-counter medicines, and alcohol. Some of the highest-risk categories include opioids such as fentanyl and heroin, benzodiazepines, cocaine, methamphetamine, prescription stimulants, alcohol, and common medications such as acetaminophen and diphenhydramine.

An overdose happens when a drug or combination of substances overwhelms the body’s ability to function safely. The effects vary by substance: opioids may dangerously slow breathing, stimulants can trigger cardiovascular or neurological emergencies, and some common medications can cause severe organ damage even when symptoms are not immediately obvious.

If you believe someone may be overdosing, call 911 immediately. If opioid exposure is possible and naloxone is available, administer it while emergency help is on the way.

Which Drugs Can Cause an Overdose?

There is no short list of drugs that are the only substances capable of causing an overdose. Prescription medications, illicit drugs, alcohol, and over-the-counter medicines can all become toxic under certain circumstances.

However, the type of medical emergency differs substantially depending on the drug.

The fact that a medication is prescribed by a physician or available without a prescription does not mean that overdose is impossible.

Opioids Carry an Especially High Risk of Fatal Overdose

Opioids include prescription pain medications such as oxycodone, hydrocodone and morphine as well as drugs such as heroin and illicitly manufactured fentanyl.

Opioids can suppress the part of the brain responsible for breathing. During an overdose, breathing may become extremely slow, irregular or stop entirely.

Illicit fentanyl has made this risk particularly important. According to the CDC, synthetic opioids—primarily illegally manufactured fentanyl and fentanyl analogs—were involved in approximately 69% of U.S. overdose deaths in 2023.

Fentanyl can also appear in counterfeit pills or be combined with other illicit substances without the person using them realizing it. This means someone may be exposed to an opioid even when they believed they were taking a different drug.

Possible signs of opioid overdose include:

• Inability to wake the person
• Very slow, shallow or stopped breathing
• Choking, gurgling or unusual snoring sounds
• Limpness
• Pale, bluish or discolored lips, skin or fingernails
• Very small, “pinpoint” pupils

Naloxone can temporarily reverse the effects of an opioid overdose. If opioid exposure is possible, administer naloxone if available and call 911. Emergency medical evaluation is still necessary even if the person wakes up.

Can You Overdose on Benzodiazepines?

Yes. Benzodiazepines such as Xanax (alprazolam), Valium (diazepam), and Klonopin (clonazepam) can cause serious toxicity when misused or taken in dangerous combinations.

The greatest concern often occurs when benzodiazepines are combined with other substances that suppress the central nervous system.

The FDA warns that combining benzodiazepines with opioids, alcohol, or other central nervous system depressants can lead to profound sedation, respiratory depression, coma and death.

Someone who regularly uses benzodiazepines should also not suddenly stop taking them without medical guidance. Physical dependence can develop, and abrupt withdrawal can cause serious complications, including seizures.

Can Cocaine or Methamphetamine Cause an Overdose?

Yes. An overdose does not always involve someone becoming unconscious or simply “falling asleep.”

Stimulants such as cocaine, methamphetamine and prescription amphetamines place significant stress on the cardiovascular and central nervous systems.

A stimulant overdose can involve:

• Severe agitation or confusion
• Extremely high body temperature
• Chest pain
• Dangerous changes in heart rhythm
• Very high blood pressure
• Seizures
• Stroke
• Heart attack
• Loss of consciousness

Stimulant overdose risk can also become less predictable when multiple substances are involved. Cocaine or methamphetamine may be used with opioids, intentionally or unintentionally, creating a medical emergency with characteristics of more than one type of overdose.

Naloxone does not reverse stimulant toxicity itself, but it should still be used when opioid exposure could be involved.

Can You Overdose on Alcohol?

Yes. Alcohol overdose—commonly called alcohol poisoning—occurs when alcohol begins interfering with the brain regions responsible for essential functions including breathing, heart rate and temperature regulation.

Warning signs can include:

• Confusion or inability to remain conscious
• Repeated vomiting
• Seizures
• Slow or irregular breathing
• Pale, bluish or clammy skin
• Reduced gag reflex
• Very low body temperature
• Inability to wake the person

Do not assume that someone who has lost consciousness after drinking can simply “sleep it off.” Alcohol already in the stomach and intestines can continue entering the bloodstream after the person stops drinking.

If a person cannot be awakened, has difficulty breathing, is experiencing seizures or appears seriously ill after drinking, call 911.

What Pills and Medicines Can You Overdose On?

You can overdose on both prescription pills and over-the-counter medicines.

Medication overdose does not only involve opioids or controlled substances. Drugs used for pain, allergies, sleep, depression and other medical conditions can cause serious poisoning when taken incorrectly, accidentally duplicated or combined with incompatible substances.

Research using FDA adverse-event reports has identified overdose reports across numerous medication categories, including opioid pain medicines, acetaminophen-type pain relievers, antidepressants, benzodiazepines, antipsychotics and other prescription drugs.

The danger depends heavily on the medication. There is no clinically responsible way to label one prescription pill as universally “safe” to overdose on.

Acetaminophen

Acetaminophen is found in Tylenol as well as hundreds of prescription and over-the-counter combination products.

Taking too much can cause severe liver injury or liver failure. One difficulty with acetaminophen poisoning is that a person may initially have mild or nonspecific symptoms despite serious internal injury developing.

Accidental overdoses can occur when someone takes several cold, flu or pain products without realizing that more than one contains acetaminophen.

Ibuprofen and Other NSAIDs

Pain relievers such as ibuprofen, naproxen and aspirin can also cause serious poisoning.

Potential complications of significant NSAID overdose include gastrointestinal irritation or bleeding, kidney injury, neurological complications, seizures and coma.

Over-the-counter availability should not be interpreted as evidence that taking more than directed is harmless.

Diphenhydramine and Other Antihistamines

Diphenhydramine, commonly sold as Benadryl and included in some allergy and sleep medications, can cause dangerous toxicity. The risk increases when mixed with alcohol or other drugs.

Overdose can produce severe sleepiness or agitation, confusion, hallucinations, rapid heart rate, seizures and coma.

Cough and Cold Medicines

Some cough and cold medicines contain dextromethorphan, antihistamines, acetaminophen or several active ingredients in a single product.

This creates two concerns: the primary medication itself can become toxic, and someone may unknowingly take excessive amounts of a second active ingredient contained in the same product.

Always check the active ingredients rather than assuming differently branded medications contain different drugs.

Can You Overdose on Prescription Medicine Even If It Was Prescribed to You?

Yes. A legitimate prescription does not eliminate overdose risk. Problems can occur if someone:

• Takes medication differently from how it was prescribed
• Combines medications without medical guidance
• Mixes a sedating medication with alcohol
• Uses opioids with benzodiazepines or other depressants
• Takes medications prescribed to someone else
• Accidentally takes repeated doses
• Uses multiple products containing the same active ingredient

Medication interactions also matter. A dose that was previously tolerated may become more dangerous when another prescription, over-the-counter medication, alcohol or illicit drug is added.

How Much of a Drug Causes an Overdose?

There is no universal amount that causes an overdose.

Overdose risk depends on the substance, potency, formulation, other substances involved, a person’s medical conditions, metabolism and tolerance, among other factors.

This is particularly important with illicit drugs because the actual contents or potency may not be known.

Tolerance can also change. Someone returning to opioid use after medical detox, treatment, incarceration or another period without use may no longer tolerate the amount they previously used. That can sharply increase overdose risk.

For these reasons, past experience with a drug does not reliably predict what will happen the next time it is used.

Why Do Overdoses Sometimes Happen Unexpectedly?

Not every overdose occurs because someone intentionally took an unusually large quantity of a drug. Several situations can make an overdose difficult to anticipate.

Mixing Multiple Substances

Polysubstance use is one of the most important overdose risks.

Opioids, benzodiazepines and alcohol can all suppress central nervous system activity. Combining them can intensify sedation and breathing problems.

Mixing stimulants with depressants does not make the substances “cancel each other out.” Instead, the body is exposed to competing and potentially dangerous effects at the same time.

Counterfeit Pills and Unexpected Fentanyl

Pills obtained outside a licensed pharmacy may look like legitimate prescription medications while containing fentanyl or other unexpected ingredients. The appearance of a pill cannot reliably establish its contents.

Changes in Tolerance

Tolerance can decrease during a period of reduced use or abstinence. Returning to a previous pattern of use can therefore produce effects that are substantially stronger than expected.

Medication Errors

Accidental overdose may result from duplicate doses, misunderstanding instructions or taking multiple combination medications containing the same active ingredient.

Older adults and people taking several medications may face additional interaction risks.

How Can You Tell If Someone Is Overdosing?

Overdose does not look exactly the same for every drug.

Depressant or opioid overdose may cause extreme sleepiness, slow breathing, loss of consciousness, choking or gurgling sounds, and skin discoloration.

Stimulant overdose may cause agitation, overheating, chest pain, severe anxiety, seizures, hallucinations, abnormal heart rhythm or stroke-like symptoms.

Alcohol overdose may involve repeated vomiting, inability to wake up, seizures, slow or irregular breathing and reduced gag reflex.

Medication poisoning can be more difficult to recognize. Some medications cause symptoms quickly, while others can cause serious internal injury before dramatic symptoms appear.

If you know or suspect that someone has taken too much medication, do not wait for severe symptoms to appear before seeking professional advice.

What Should You Do If Someone May Be Overdosing?

Treat a suspected overdose as a medical emergency.

Call 911 immediately if the person is unconscious, cannot be awakened, has trouble breathing, is having a seizure or appears seriously ill.

If opioid exposure is possible:

1. Give naloxone if it is available.
2. Call 911.
3. Try to keep the person breathing and responsive.
4. Place an unconscious but breathing person on their side to reduce choking risk.
5. Stay with them until emergency help arrives.

Do not attempt to make the person vomit unless a medical professional or poison specialist specifically tells you to do so.

For suspected medication poisoning, you can also contact Poison Help at 1-800-222-1222.

If the overdose may have been intentional or the person is experiencing thoughts of suicide or self-harm, emergency medical care is still the immediate priority. The 988 Suicide & Crisis Lifeline is also available by calling or texting 988.

When Does Overdose Risk Become a Sign That Treatment May Be Needed?

An overdose does not automatically mean that someone has a substance use disorder. Accidental medication errors and one-time exposures can occur. However, overdose or repeated near-overdose situations can be an important warning sign when they occur alongside patterns such as:

• Needing increasingly more of a drug to achieve the same effect
• Using more often or for longer than intended
• Being unable to reduce or stop use
• Combining drugs despite knowing the risks
• Using drugs to prevent withdrawal symptoms
• Returning to use repeatedly after trying to stop
• Using counterfeit or illicit pills
• Continuing after a previous overdose
• Substance use interfering with relationships, work, health or responsibilities

The question at that point is no longer simply, “Can I overdose on this drug?” It may be whether continued use has become difficult to control and whether another overdose could occur. That is an appropriate time to seek a professional substance use assessment.

What Treatment May Be Appropriate After an Overdose?

Addiction treatment does not replace emergency overdose care. A suspected overdose should first be treated by emergency medical professionals. Once someone is medically stable, treatment can address the substance use pattern that contributed to the overdose risk.

The appropriate level of care depends on the substances involved, withdrawal risk, medical and psychiatric needs, previous treatment history, living environment and ability to remain stable outside a structured setting.

For some people, treatment may begin with medical detox, particularly when withdrawal could require medical monitoring. Others may benefit from residential or inpatient treatment followed by partial hospitalization, intensive outpatient care, outpatient treatment and continuing recovery support.

People who have experienced an opioid overdose may also benefit from discussing medications for opioid use disorder and continued access to naloxone with qualified medical professionals.

Reduce the Risk of Another Overdose

If substance use has become difficult to control—or an overdose, relapse or close call has already occurred—you do not have to wait for another emergency before exploring treatment.

Legacy Healing Center provides individualized addiction treatment across multiple levels of care, including medical detox, residential and inpatient treatment, outpatient programming and continuing recovery support.

Our admissions team can help determine what level of care may be appropriate, discuss available treatment locations and review insurance benefits before admission.

Speak confidentially with an admissions specialist at 888-534-2295 or verify your insurance coverage to explore your treatment options.