The three hallmark signs of an opioid overdose are pinpoint pupils, unconsciousness, and slowed or stopped breathing. Recognizing these signs quickly matters: opioid overdoses killed over 54,000 people in the United States in 2024, and most of those deaths involved synthetic opioids like fentanyl. An overdose is survivable when caught early, so knowing exactly what to look for can be the difference between life and death.
The Classic Three Signs
The World Health Organization identifies a combination of three signs that together point to an opioid overdose: pinpoint pupils, unconsciousness, and difficulty breathing. You may see all three at once, or they may develop over minutes as the drug takes fuller effect.
Pinpoint pupils. Opioids cause the pupils to constrict so tightly they look like tiny dots, even in dim lighting. Normally, your pupils widen in the dark and shrink in bright light. During an overdose, they stay extremely small regardless of the light around them, and the constriction appears in both eyes equally.
Unconsciousness or unresponsiveness. The person cannot be woken up by calling their name, shaking them, or rubbing your knuckles firmly on their breastbone (a technique called a sternal rub). This is different from being asleep. A person who is simply sleeping will stir or respond to pain. Someone overdosing will not.
Slow, shallow, or stopped breathing. This is the sign that kills. Opioids work by suppressing a small cluster of roughly 70 to 140 neurons in the brainstem that generate the breathing rhythm. When those neurons are overwhelmed, the body’s automatic drive to breathe slows dramatically or stops altogether. Breathing below about 10 breaths per minute is a red flag. For reference, a healthy adult at rest breathes 12 to 20 times per minute.
Skin and Color Changes
When breathing slows, the body stops getting enough oxygen. This causes visible color changes in the skin, lips, and fingernails. On lighter skin, you’ll see a bluish-purple tint, especially around the lips and fingertips. On darker skin, the change looks grayish or ashen rather than blue. Either way, the person’s complexion will look distinctly “off” compared to their normal tone. The face may also appear pale or clammy to the touch.
Sounds That Signal Trouble
One of the most commonly missed warning signs is sound. A person overdosing may produce choking, gurgling, or deep snore-like noises, sometimes referred to as a “death rattle.” These sounds happen because the muscles in the throat relax and the airway partially collapses, or because fluid pools in the back of the throat.
This is a critical point: many people have mistaken these sounds for ordinary snoring and left a loved one alone, only to find them later not breathing. If someone who has used opioids is making unfamiliar sounds while appearing to sleep, try to wake them immediately. Normal snoring allows the person to be roused. An overdose does not.
How an Overdose Looks Different From Being High
Opioids naturally cause drowsiness, so it can be hard to tell when someone has crossed from intoxication into a medical emergency. The key differences come down to responsiveness and breathing. A person who is high may nod off, have slurred speech, and appear very relaxed, but they can still be woken up. Their breathing, while possibly slow, remains steady and audible.
During an overdose, the person becomes completely unresponsive. Their body goes limp. Their breathing becomes irregular, with long pauses between breaths, or it stops entirely. Their skin color changes. If you’re unsure whether someone is dangerously high or actively overdosing, err on the side of treating it as an overdose. There is no medical downside to acting too soon.
Fentanyl Can Cause Additional Symptoms
Fentanyl, which was involved in nearly 48,000 overdose deaths in 2024, can produce a symptom that other opioids typically do not. Known as “wooden chest syndrome,” it causes the muscles of the chest and torso to become rigid, making it physically difficult for the person to breathe even if their brain is still sending the signal to do so. Fentanyl triggers this rigidity through a mechanism separate from how it acts as a painkiller. It directly affects potassium channels in motor neurons, causing muscles to lock up.
This rigidity can also make rescue breathing harder to perform, because the chest wall resists expansion. If you encounter someone whose torso feels unusually stiff and who is not breathing, this is consistent with a fentanyl-related overdose and requires immediate emergency response.
What to Do When You See These Signs
Call 911 immediately. While waiting for help, the most effective intervention is naloxone, a medication that temporarily reverses the effects of opioids. The nasal spray version delivers 3 or 4 milligrams in a single spray into one nostril. If the person doesn’t respond within 2 to 3 minutes, give a second dose. Naloxone is available without a prescription at most pharmacies in the U.S.
If the person is not breathing or is breathing very slowly, begin rescue breathing: tilt their head back, lift the chin, and give one breath every 5 seconds. If you cannot perform rescue breathing or the person has no pulse, start CPR. Place the person on their side (the recovery position) if they are breathing on their own but still unconscious, to prevent choking if they vomit.
Naloxone wears off in 30 to 90 minutes, which is often shorter than the duration of the opioid itself. This means a person can slip back into an overdose after initially waking up. Stay with them until paramedics arrive, and monitor their breathing continuously. If breathing drops below 10 breaths per minute again, give another dose of naloxone.