Opioids are the most common cause of pinpoint pupils. Heroin, fentanyl, oxycodone, hydrocodone, morphine, and other opioids shrink the pupils to tiny dots that stay small even in dim light. A few other medications and medical conditions can cause small pupils too, but outside a hospital, opioids are by far the most likely explanation.

This guide covers which drugs cause pinpoint pupils, why opioids have this effect, which drugs do the opposite, and what else can make pupils small.

What Are Pinpoint Pupils?

Pinpoint pupils, called miosis in medical terms, are pupils that are constricted to an unusually small size, typically 2 millimeters or less. For comparison, a normal pupil is about 2 to 4 millimeters in bright light and widens to 4 to 8 millimeters in the dark.

The key difference is response to light. Normal pupils widen when the lights go down. Pinpoint pupils from opioids barely change, so they look like small dots even in a dim room. If you notice someone’s pupils staying tiny in low light, that’s the sign worth paying attention to.

What Drugs Cause Pinpoint Pupils?

Opioids are the main cause. Almost every opioid constricts the pupils, including:

• Heroin
• Fentanyl, including illicit fentanyl and fentanyl analogues
• Oxycodone (OxyContin, Percocet)
• Hydrocodone (Vicodin, Norco)
• Morphine
• Codeine
• Buprenorphine (Suboxone)
• Tramadol

A smaller group of other medications can also make pupils small:

• Clonidine: a blood pressure medication, sometimes used to ease opioid withdrawal symptoms
• Some antipsychotics: certain older antipsychotic medications can mildly constrict the pupils
• Glaucoma eye drops: drops such as pilocarpine are designed to shrink the pupil

When someone has pinpoint pupils along with drowsiness, slurred speech, or nodding off, opioids are the most likely cause.

Why Do Opioids Cause Pinpoint Pupils?

Opioids act on mu-opioid receptors in the brainstem, including the area that controls the muscle that tightens the pupil (the Edinger-Westphal nucleus). Activating that system makes the ring of muscle in the iris contract.

Because the opioid is acting on the nerve control itself, it overrides the normal light response. That’s why opioid pupils stay small in the dark, and why the body builds little tolerance to this effect. Even people who use opioids daily usually still have small pupils while the drug is active.

Do Other Drugs Cause Small Pupils?

Most other commonly misused drugs don’t cause pinpoint pupils:

• Benzodiazepines (Xanax, Klonopin, Valium): these don’t typically cause pinpoint pupils. If someone has tiny pupils after taking benzos, opioids may be involved too, which is a dangerous combination
• Alcohol: doesn’t usually cause pinpoint pupils
• Marijuana: doesn’t cause pinpoint pupils; it’s more often linked to red eyes

Pinpoint vs. Dilated Pupils: Drugs That Do the Opposite

Many drugs widen the pupils instead. Dilated pupils (mydriasis) are common with:

• Cocaine
• Methamphetamine
• Prescription stimulants like Adderall
• MDMA (ecstasy)
• Hallucinogens like LSD and psilocybin

Opioid withdrawal also dilates the pupils. So someone who uses opioids may have pinpoint pupils while the drug is active and unusually large pupils as it wears off.

Other Medical Causes of Pinpoint Pupils

Drugs aren’t the only explanation. Small pupils can also come from:

• Horner’s syndrome: a nerve problem that usually affects only one eye, often with a drooping eyelid
• Bleeding in the brainstem: a pontine hemorrhage, a type of stroke, can cause pinpoint pupils in both eyes and is a medical emergency
• Organophosphate poisoning: exposure to certain insecticides or nerve agents
• Aging: pupils naturally get smaller with age
• Eye inflammation: conditions such as iritis can constrict the pupil

If small pupils appear suddenly with confusion, weakness, or trouble speaking, call 911.

When Pinpoint Pupils Are an Emergency

Pinpoint pupils on their own aren’t an emergency. They become one when they show up with signs that breathing is being suppressed: the person can’t be woken, breathing is very slow or stopped, or lips are turning blue or gray. Together, those signs can mean an opioid overdose. Call 911 and give Narcan if you have it.

Our guide to pinpoint pupils and overdose walks through the warning signs and exactly what to do.

Frequently Asked Questions

What Are Pinpoint Pupils a Sign Of?

Most often, they’re a sign that opioids are active in the body. Less often, they come from medications like clonidine, glaucoma eye drops, a nerve condition like Horner’s syndrome, or a brainstem stroke.

What Drugs Make Your Pupils Small?

Opioids, including heroin, fentanyl, oxycodone, hydrocodone, morphine, codeine, buprenorphine, and tramadol. Clonidine, some antipsychotics, and certain eye drops can also make pupils small.

Do Benzos Cause Pinpoint Pupils?

Not typically. Benzodiazepines like Xanax and Klonopin usually leave pupil size close to normal. Pinpoint pupils in someone who took benzos may point to opioids as well.

What Does Fentanyl Do to Your Pupils?

Fentanyl constricts the pupils like other opioids, often to pinpoint size. Because fentanyl is very potent, pinpoint pupils with drowsiness after possible fentanyl exposure should be watched closely.

Does Adderall Cause Pinpoint Pupils?

No. Adderall and other stimulants usually dilate the pupils. Pinpoint pupils point toward opioids, not stimulants.

Getting Help for Opioid Use

If pinpoint pupils are showing up again and again, it often means opioids are being used regularly. Small pupils are one physical sign among several; our guide to the signs of opioid addiction covers the rest.

Waterside Recovery offers outpatient care across Plymouth County, the South Shore, and MetroWest. Learn more about opioid addiction treatment at Waterside, call (866) 671-8620, or verify your insurance to see what’s covered.