Dilated Pupils Drugs: What Drugs Cause Pupils to Dilate?

Many types of drugs can cause physical and mental effects, including commonly used prescriptions and drugs of abuse like cocaine and opioids. The eyes are often one of the immediate signs of drug use, including the size of the pupils.

Substance abuse or addiction can cause constriction or dilation of the eyes, which is an obvious sign of drug use. However, other drugs and conditions can cause dilated pupils, so it’s not a lone indicator.

What Causes Pupils to Dilate?

Pupils are the dark part of the eye that expand and constrict according to the light. They will constrict in bright light to protect the eye or dilate in dim light to allow more light to enter the retina and help you see better. The technical term for dilated pupils is mydriasis.

Some other factors can cause the pupil to dilate or constrict, such as certain health conditions, brain and eye injuries, your mental and emotional state, and prescription or illicit drugs.[1]

What Drugs Cause Dilated Pupils?

Any drugs that affect the muscles can make the pupils dilate or constrict. Here are some prescription and over-the-counter (OTC) drugs that can cause the pupils to dilate:

• Anticholinergics: These drugs block the action of acetylcholine, a neurotransmitter involved in muscle contractions.[2]
• Anticonvulsants and antiepileptics: Antiepileptics, including barbiturates like phenobarbital, affect the brain’s neurotransmitter activity or nerve impulses.[3]
• Antidepressants: Tricyclic antidepressants impact serotonin and norepinephrine, which affect bodily functions, including eye movement.[4]
• Antihistamines: Antihistamines block the action of histamine, an immune response that triggers allergy symptoms like itchiness, congestion, and swelling.[5]
• Decongestants: Decongestants constrict the blood vessels in the nose to treat swelling, inflammation, and mucus buildup with colds or allergies.[6]
• Dopamine precursors: Dopamine precursors can increase dopamine synthesis, leading to dilated pupils.[7]
• Mydriatics: Mydriatics are drugs that cause pupil dilations and are used in eye exams and surgeries.[8]
• Stimulants: Stimulants like Ritalin and Adderall are used in the treatment of attention deficit hyperactivity disorder (ADHD) and cause pupils to dilate.[9]
• Selective serotonin reuptake inhibitors (SSRIs): SSRIs influence the effects of serotonin in the brain to treat depression and other mental health conditions.[10]

Can Drug Abuse or Misuse Dilate the Pupils?

Drug misuse or abuse can have effects on the eyes, including pupil dilation or constriction. Some drugs cause severe eye consequences, such as excessive alcohol use that can lead to vision loss.

Some drugs cause eye changes immediately after using them, such as marijuana causing bloodshot eyes. Others may take more time to see the effects on the eye.

The severity of eye changes and the specific changes depend on the type of substance and how it’s used. Some commonly misused drugs that cause dilated pupils include:

• Amphetamines like Adderall
• Stimulants like cocaine and crystal meth
• MDMA
• LSD
• Mescaline
• Bath salts

Many drugs act on the central nervous system or the brain’s neurotransmitters, leading to dilated pupils. Stimulants like amphetamines speed up the central nervous system, causing the pupils to dilate. Conversely, drugs that stimulate serotonin agonize the 5-HT2A receptors in the brain, causing dilation.

Dilated pupils are common with many drugs, but some drugs have the opposite effect. Opioids like fentanyl, heroin, morphine, and oxycodone cause pinpoint pupils, or miosis. These drugs cause the pupils to constrict.[11] Pinpoint pupils won’t respond to changes in lighting, which can be a sign of an opioid overdose and a medical emergency.

Can a Drug Cause Permanent Pupil Dilation?

The dilated pupils that happen with some drugs often occur at the same time as the drug’s effects. Once the effects wear off, the pupils return to their normal pupil size. However, this can depend on the drug. Pupil dilation can be a sign of withdrawal from some drugs, such as opioids.

Though there’s not a lot of research into the permanent effects of drugs on the eyes or the pupils, there is one study from 2017 that evaluated long-term changes in pupil size from hallucinogen use. However, there’s not sufficient evidence that permanent eye changes are a risk of drug abuse.[12]

What Can I Do for Dilated Pupils?

If your pupils are dilated, they won’t react to light changes as quickly. This can make your eyes sensitive to bright light. If your pupils are dilated regularly from prescription medication, it’s important to protect them properly in sunlight or other bright lights.

Using polarized lenses can ensure that the glare from sunlight reflected off light surfaces like snow or water is sufficiently blocked. Photochromic lenses, used indoors and outdoors, darken to protect your eyes from light changes. Speak to your doctor about your options.

Do I Need Medical Attention for Dilated Pupils?

Talk to your doctor if you have dilated pupils from a prescription medication. It’s a common side effect of certain drugs, but it’s still worth discussing with your doctor to ensure it’s not a sign of something serious.

If you notice dilated pupils in a loved one that aren’t explained by prescription medications, it may indicate drug abuse or a substance use disorder (addiction). However, pupil dilation isn’t a sign of drug use on its own.

Is Pupil Dilation a Sign of Drug Use?

Pupil dilation can be a clear sign of drug use, but it’s not enough to be sure someone is abusing or addicted to drugs on its own. Typically, dilated pupils that are combined with other indicators like mood swings, weight changes, appetite changes, sleep disturbances, or poor hygiene can be an indicator, depending on the drug involved.

There may be other signs of drug abuse, such as social isolation, visiting multiple doctors for prescriptions, financial problems with no explanation, and recurrent problems at work, school, or home.

If you’re concerned about a loved one’s drug use, medical teams and law enforcement have a chart that shows how pupils react to different drugs, the “Drug Recognition Card.”[13] This chart is based on the standards set by the International Association of the Chiefs of Police (IACP). It offers a reference to identify substance abuse based on common categories like depressants, stimulants, opioids, cannabis, hallucinogens, and phencyclidine.

Treating Substance Abuse

If you’re worried that someone you love is using drugs or showing signs of substance abuse or addiction, it’s important to get help as soon as possible. Addiction can have devastating effects on the body, mind, and well-being. Addiction treatment centers offer hope with comprehensive care and personalized treatment plans that may include detox, inpatient and outpatient treatment, and behavioral therapies.

Dilated Pupils and Drug Use

Dilated pupils can be caused by prescription drugs or drugs of abuse. Some drugs cause pupil dilation as a side effect, but pupil dilation can be a sign of drug abuse. Dilated pupils aren’t usually a cause for concern about eye health, but you should talk to your doctor if you’re worried.