Overdose signs can look different by substance.

A drug overdose may involve opioids, stimulants, alcohol, benzodiazepines, or mixed substances. Common warning patterns include slowed, stopped, or irregular breathing and major changes in alertness, according to the National Institute on Drug Abuse and SAMHSA.

Signs may start small, then get worse fast.

• Opioids: very slow breathing, tiny pupils, blue or gray lips, hard to wake
• Stimulants: chest pain, very high body heat, agitation, seizures
• Alcohol or benzodiazepines: vomiting, confusion, slowed breathing, passing out

Polysubstance use raises danger.

Polysubstance use can hide or mix overdose signs. For example, stimulants may mask sedation at first, while alcohol, opioids, and benzodiazepines together can sharply slow breathing.

Time matters.

Prompt recognition improves the chance of survival and recovery. If a person seems unresponsive, hard to wake, or medically unstable, treat it as an emergency.

Clinical definition

An overdose happens when a drug amount causes harmful toxicity and overwhelms the body. Effects can range from severe confusion to slowed breathing, organ damage, coma, or death, depending on the drug and dose. This matches clinical definitions used by NIDA and CDC.

How overdose differs from intoxication

Intoxication means the drug is affecting the brain and behavior. An overdose is more serious: the drug causes dangerous toxicity. For example, alcohol intoxication may cause poor balance, while alcohol overdose can cause vomiting, unresponsiveness, or central nervous system depression with slowed breathing.

How overdose differs from withdrawal

Withdrawal happens when a person stops or cuts back a substance after regular use. Overdose comes from too much of a substance in the body. Both can be life-threatening, but they are different medical problems, according to SAMHSA.

Why overdose signs differ by substance

• Opioids often cause pinpoint pupils and slow breathing.
• Stimulants may cause chest pain, overheating, or seizures.
• Sedatives can cause heavy sleepiness and slowed breathing.

Overdoses may be unintentional or intentional. Risk rises with mixing drugs, unknown strength, relapse after abstinence, or taking more than the body can safely handle.

Overdose happens when a drug overwhelms the body’s vital functions.

Opioid-induced respiratory depression slows or stops breathing. Fentanyl contamination raises risk because it is much stronger than many other opioids and may be hidden in counterfeit pills or powders.

Sedatives and alcohol can shut the brain and body down.

Benzodiazepines and alcohol both depress the central nervous system. Together, they can sharply worsen sleepiness, slow breathing, and loss of consciousness.

Stimulants can push the heart and brain into crisis.

Stimulant toxicity can cause very high body temperature, chest pain, seizures, stroke, or dangerous heart rhythms. This risk is seen with drugs like cocaine and methamphetamine.

Mixing substances changes toxicity and signs.

• Drug interactions can make symptoms less predictable.
• Opioids plus alcohol or benzodiazepines increase breathing failure risk.
• Stimulants plus opioids may mask warning signs until the overdose becomes severe.

Opioids

• Opioid overdose often causes very slow or stopped breathing, pinpoint pupils, blue or gray lips, and a person who will not wake up. This can happen with opioids like fentanyl and heroin.

Stimulants

• Cocaine and methamphetamine overdose signs often include chest pain, very fast heartbeat, high body temperature, severe agitation, panic, tremors, or seizures.

Alcohol

• Alcohol overdose can cause vomiting, slow or irregular breathing, confusion, pale or blue skin, low body temperature, and passing out.

Benzodiazepines or Sedatives

• Benzodiazepines and other sedatives may cause extreme sleepiness, slurred speech, poor balance, confusion, and slow breathing. Risk rises when they are taken with alcohol or opioids.

Mixed-Substance and Overlapping Signs

• Polysubstance overdose can show mixed signs, such as slow breathing plus chest pain, or deep sleep plus vomiting. Signs that overlap across substances include unresponsiveness, breathing changes, seizures, blue lips, and confusion.

Breathing and Consciousness Changes

Severe overdose often causes respiratory depression. Warning signs include slow, shallow, or stopped breathing, hard-to-wake sleep, no response, and cyanosis of the lips or fingertips. Pinpoint pupils can happen with opioid overdose.

Skin, Coordination, and Collapse

• Skin may turn blue, gray, pale, cold, or sweaty.
• Loss of coordination, confusion, slurred speech, or sudden collapse can signal rapid decline.
• Very high body temperature can happen with stimulant overdose, while severe opioid overdose may cause cool skin.

Seizures, Heart Problems, and Aspiration Risk

• A seizure, severe agitation, panic, or hallucinations can occur with stimulant or mixed-drug overdose.
• Chest pain, pounding heartbeat, or an arrhythmia raise concern for heart danger.
• Vomiting, gurgling, choking, or lying unresponsive increases aspiration risk.

Overdose trends

CDC and NIDA data show that overdose mortality in the U.S. remains high, with opioids involved in most drug overdose deaths. Rates changed over time, but deaths linked to fentanyl and other synthetic opioids rose sharply.

Highest-risk substances

• Synthetic opioids, especially fentanyl, are most tied to fatal overdose.
• Other major drivers include methamphetamine, cocaine, and benzodiazepines, often with opioids.
• SAMHSA warns that mixed-substance use raises risk because drugs can slow breathing, increase sedation, or hide warning signs.

Why early recognition matters

Clinical evidence shows survival improves when overdose is recognized early and treated fast, especially for opioid overdose. Public health guidance from CDC and SAMHSA stresses that spotting slowed breathing, unresponsiveness, or blue lips early can change outcomes.

Act fast and call emergency services

Call 911 right away. Tell EMS what the person took, if known, and whether they are breathing. Fast medical care improves survival, especially with opioid, stimulant, or mixed-drug overdoses, according to the CDC.

Use naloxone if opioid overdose is possible

Give naloxone if the person has slow breathing, no breathing, blue lips, or cannot wake up. Give a second dose in 2 to 3 minutes if needed. Naloxone will not treat non-opioid overdoses, but it will not harm someone if opioids are not present.

Stay with the person and monitor them

• Keep checking breathing and responsiveness.
• If they are breathing but unconscious, place them on their side.
• If they stop breathing, start rescue breathing or CPR if you know how.
• Do not leave them alone.

What to do after the crisis

After medical stabilization, a post-overdose evaluation is important. Follow-up may include withdrawal monitoring, mental health screening, and treatment planning to lower the risk of another overdose.