An overdose looks different depending on the substance involved, but the core warning signs fall into recognizable patterns. Opioids slow breathing and consciousness. Stimulants send the heart racing and body temperature soaring. Depressants like alcohol and sedatives cause deep drowsiness and loss of coordination. Knowing what to look for across these categories can help you act fast when someone’s life is at risk. In 2024, 79,384 people in the United States died from drug overdoses.
Opioid Overdose: The Classic Triad
Opioid overdose produces three hallmark signs that appear together: pinpoint pupils, slowed or stopped breathing, and a dropping level of consciousness. This combination is so consistent it’s known as the “opioid overdose triad,” and recognizing it is the single most important thing you can learn about overdose recognition.
Breathing changes are the most dangerous part. A person overdosing on opioids may breathe as few as 4 to 6 times per minute, compared to the normal 12 to 20. Their breaths become shallow and irregular, sometimes with long pauses between them. You might hear gurgling or choking sounds. Their lips, fingertips, or face may turn blue or grayish as oxygen levels drop. Skin may also appear flushed or itchy, since many opioids trigger histamine release.
The person may be impossible to wake up. You can try calling their name, rubbing your knuckles hard on their breastbone, or pinching their earlobe. If none of that produces a response, they need emergency help immediately. Some people appear to be snoring deeply, which bystanders mistake for sleep. Heavy, labored snoring in someone who recently used opioids is not normal sleep. It often signals that the airway is partially blocked.
Fentanyl, which now drives the majority of opioid overdose deaths in the U.S., can cause an additional complication: chest wall rigidity, sometimes called “wooden chest syndrome.” The muscles of the chest and abdomen lock up, making it extremely difficult or impossible for the person to breathe even if they’re conscious. Physical signs include what look like breath-holding spells, a tightly clenched jaw, stiff limbs, and a rigid abdomen.
Stimulant Overdose: Overheating and Agitation
Stimulant overdose looks almost like the opposite of an opioid overdose. Instead of slowing down, everything speeds up. The pupils dilate wide. The heart races. Blood pressure spikes. The person sweats heavily, their mouth goes dry, and their body temperature climbs to dangerous levels. These signs apply to cocaine, methamphetamine, MDMA, and prescription stimulants taken in excess.
Behavioral changes are often the first thing bystanders notice. The person may become intensely agitated, paranoid, or aggressive. Psychotic symptoms during stimulant use are surprisingly common. Studies of cocaine users with psychotic episodes found that about 90% experienced paranoid delusions and 96% had hallucinations, most often hearing things that weren’t there. Methamphetamine and synthetic stimulants produce similar effects, with agitation ranging from restlessness to full-blown delirium with hallucinations and violent behavior.
The most life-threatening signs are seizures, an irregular or stopped heartbeat, and extremely high body temperature. If someone is seizing, do not hold them down or put anything in their mouth. Gently protect the back of their head from hitting the ground, and turn them on their side if possible so they don’t choke on vomit. Call emergency services immediately.
Depressant Overdose: Sedation and Collapse
Alcohol, benzodiazepines (like Xanax or Valium), and other sedatives cause overdose by depressing the central nervous system too far. The earliest sign is typically slurred speech and loss of coordination. In children, unsteadiness while walking is the most common indicator, appearing in about 90% of cases.
As toxicity worsens, drowsiness deepens from heavy sedation into a stupor or coma-like state. A key distinction from opioid overdose: in an isolated benzodiazepine overdose, vital signs like heart rate and blood pressure often remain relatively normal even while the person is deeply unconscious. This can be misleading. A person who looks like they’re “just sleeping” may actually be unable to protect their own airway, and vomiting while unconscious is a major cause of death.
The danger multiplies when depressants are combined. Mixing alcohol with benzodiazepines, or either one with opioids, dramatically increases the risk of fatal respiratory failure. Many overdose deaths involve more than one substance.
Serotonin Syndrome
Some overdoses don’t fit neatly into the categories above. Serotonin syndrome occurs when too much of the brain chemical serotonin builds up, usually from combining medications like antidepressants with other drugs that boost serotonin levels. It looks different from a typical overdose in specific ways: the person develops involuntary muscle jerking (rhythmic twitching, especially in the legs and feet), exaggerated reflexes, and rising body temperature. The muscle jerking tends to start in the lower body and spread upward as the condition worsens. High fever combined with these rhythmic muscle movements is a distinguishing feature that separates serotonin syndrome from other types of drug toxicity.
How to Respond
Call emergency services first. While waiting, the most important things you can do depend on the situation.
If the person is unconscious but breathing, place them in the recovery position to keep their airway clear. Kneel beside them while they’re on their back. Extend their nearest arm out at a right angle with the palm facing up. Take their other hand and place the back of it against the cheek closest to you. Bend the far knee to a right angle, then gently roll them toward you by pulling that bent knee. Their head should rest on their own hand, and the bent leg keeps them stable on their side. Tilt their head back slightly and lift their chin to open the airway.
If you suspect opioid overdose and have naloxone available, give one dose. Naloxone can restore normal breathing within 2 to 3 minutes. If breathing doesn’t improve after 2 to 3 minutes, give a second dose. Naloxone only works on opioids, so it won’t help with stimulant or sedative overdoses, but it also won’t cause harm if you’re unsure what the person took. Since many street drugs now contain fentanyl regardless of what they’re sold as, using naloxone when you see the signs of slowed breathing and unconsciousness is a reasonable response even if you don’t know exactly what was used.
Stay with the person until help arrives. People who receive naloxone can slip back into overdose once it wears off, typically within 30 to 90 minutes, because many opioids last longer in the body than naloxone does.