This chart compares pupil diameter on individuals who have ingested the various substances listed above, as well as categories such as light reaction, convergence, and gaze.Īccessing the resource may provide some insight into which substance a person has taken if any.

Alcohol, cocaine, and marijuana may cause bloodshot eyes since these substances cause the blood vessels around the pupils to expand.įirst responders use a resource, the Drug Recognition Card, developed by the International Association of Chiefs of Police. If your friend or family member displays this symptom, call 911 as it could indicate an overdose. The pupils get smaller and do not respond to light. Some drugs, most commonly opioids such as heroin, cause pinpoint pupils. This symptom tends to wear off, along with the other effects of the drug. Pupil dilation is also associated with heroin and opioid withdrawal. However, this symptom can result from ingesting alcohol, mescaline, cocaine, ecstasy, LSD, psilocybin, MDMA, amphetamines, cannabis, inhalants, narcotics, hallucinogens, bath salts, ketamine, and SSRI antidepressants. Stimulants and psychotropic substances most commonly cause pupil dilation. This chemical reaction leads to mydriasis, the muscle relaxation that allows the eye’s pupil to expand and let in more light. Some substances trigger the body’s fight or flight adrenaline response by interacting with serotonin and adrenergic receptors in the brain. Learn more about what drugs cause dilated pupils as well as other potential red flags for addiction. Are you concerned about signs of drug use in your child or another loved one? Dilated pupils, an enlargement of the black portion of the center of the eye, are one common symptom of substance use.

Eye pupil size meaning