Dilated or enlarged pupils are one of the common indicators of substance use or being “high.” Other medications can cause these effects, and some substances have the opposite effect, pinpoint eyes or constricted pupils. Let’s break down everything you need to know about dilated pupils and drugs.
The eyes are often seen as the windows to the soul. As windows, the eyes tell a story. Pupil dilation could indicate many things, one of which is substance use. A few other medical conditions or medications could influence pupil size and shape, so knowing the difference is important.
What are dilated pupils?
Dilated pupils are officially called mydriasis, an autonomic sympathetic nervous system response that widens or enlarges the pupils, minimizing the iris. This is natural, a response to some external stimuli. In addition to substances, stimulation of dilated pupils could be triggered by:[1]
- Attention
- Arousal
- Emotion
- Interest
- Mental workload
What substances cause dilated pupils?
Many substances can cause dilated pupils, including stimulants, prescription medications, anxiety medications, painkillers, and more.
Alcohol and Dilated Pupils
Alcohol is the most readily available legal substance that can lead to substance use disorder and is also tied to dilated pupil effects. Medical studies have connected the intensity of pupil response to alcohol to indicate a higher potential for relapse in alcohol-dependent patients.[2] Meaning, the more dilated the pupils get due to alcohol being on board, the more likely one is to relapse.
Anticholinergics and Dilated Pupils
Anticholinergics are substances found in many prescription medications that affect several parts of the eye. It is also associated with blurred vision and dizziness and may be found in anti-seizure drugs, Parkinson’s medications, antihistamines and allergy medications, Botox, decongestants, antidepressants, and more.[3]
Amphetamines and Stimulants and Dilated Pupils
Amphetamines are stimulant substances that accelerate the activity of the central nervous system. Both prescription and illicit amphetamine substances can stimulate pupil dilation, including Adderall, methamphetamine, Desoxyn, Vyvanse, Dexedrine Spansule, and more.[4]
Cocaine and Dilated Pupils
Cocaine is a highly potent stimulant substance that’s classified as a Schedule II controlled substance due to the lack of medical application and high potential for abuse. This dangerously powerful drug’s effects begin within 1-3 minutes of the last dose and last for approximately 30 minutes, and one of those effects is dilated pupils.[5]
LSD (Acid), Psilocybin, and Mescaline and Dilated Pupils
These are hallucinogenic substances or party drugs that can cause a sensation of ecstasy, and hallucinations, or “trips.” These substances trigger a hyperarousal of the central nervous system, which can be associated with dilated pupils. [6]
Mydriatics and Dilated Pupils
Mydriatics are eye drops used by ophthalmologists and optometrists. This medication is usually applied before an optical exam or surgery to change the shape of the pupil.[7] The effects wear off within 4 to 8 hours, but could take as long as 24 hours and may cause light sensitivity.
Marijuana or Cannabinoids and Dilated Pupils
Dilated pupils and eyes that sluggishly react to light are a common side effect of marijuana use. These effects can sometimes last from 1 to 3 hours. Frequent or long-term cannabis use can lead to eye infections, dilated pupils, and impaired oculomotor function (adverse effects on eye movement.)[8]
Designer Bath Salts
Bath salts are dangerous synthetic cathinones, which are central nervous system stimulants that elicit mind-altering effects. The primary ingredient is Methylenedioxypyrovalerone (MDPV), which is similar to MDMA or ecstasy. Along with euphoria and hallucinations, one of the chief side effects is dilated pupils.[9]
Dilated Pupils and Drugs Chart
Not all substances cause dilated pupils, and some trigger the opposite effect. The following chart is based on medical studies conducted to determine the effects of illicit or misused substances on the eye.[10]
| Substance Type | Pupil Effects |
| Marijuana | Dilated or normal |
| Opioids | Constricted |
| CNS Stimulants | Dilated |
| CNS Depressants (Benzodiazepines, Barbiturates, etc.) | Normal or variable |
| Hallucinogens | Dilated |
| Phencyclidine (PCP) | Not common |
Other Eye Effects Related To Substance Use
Red Eyes
Red or bloodshot eyes occur when the veins and small blood vessels in the eye are swollen. Every day triggers, like allergies or crying, could cause it, but it is also associated with some substances.
What Drugs Cause Red Eyes?
Drugs that are linked to bloodshot eyes include:
- Marijuana
- Cocaine
- Hallucinogens
- Nicotine
Pinpoint Eyes
Pinpoint or pinprick eyes are also known as constricted pupils or miosis. This is when the pupils are much smaller than normal and could be caused by natural triggers like bright lights, emotional stress, sleep deprivation, and some substances.
Drugs That Constrict Pupils
Drugs that are linked to constricted pupils include:[12]
- Opiates or opioids
- Painkillers
- Heroin
A Note About Barbiturates and Benzodiazepines
Benzodiazepines and barbiturates are central nervous system (CNS) depressants. They slow the nervous system function to induce calm. They’re often prescribed for anxiety disorders, panic disorders, and other physical and mental health conditions. When taken as prescribed, the effects on the eyes are minimal, but when misused or taken outside of specified instructions, they can change pupil function.
Are dilated pupils a sign of drug use?
They can be. Drugs and pupil dilation are connected, and the various drug effects can also be influenced by how the substance is taken (injected, inhaled, ingested, etc.). Pupil dilation due to substances is often linked to stimulant abuse. However, other causes of pupil dilation have nothing to do with substance abuse.
Medical Reasons for Enlarged Pupils
Someone with enlarged or wide pupils may not be abusing substances. Pupil dilation can be from other medical conditions or injuries, including:[13]
- Eye injuries
- Migraines
- Brain injury
- Concussion
- Adie’s Syndrome
- Microvascular cranial nerve palsy (MCNP)
- Benign episodic unilateral mydriasis (BEUM)
Long-Term Impact on the Eyes from Substance Misuse
Different substances will leave a different mark on overall health, especially with frequent or long-term use. Adverse effects and long-term health risks for optical health can also be affected. Here’s a look at how different substances can impact eye health:[14]
- Alcohol: Over time, alcohol changes the numerous microorganisms that live in the eye and eyelids due to increased bacteria, which can increase the risk of infection. Alcohol is also linked to eye weakness and accelerated age-related macular degeneration.
- Nicotine: Smoking nicotine can trigger abnormal changes or rough patches in the eye, decrease the rate of cornea healing, increase the risk of Graves’ eye disease, and lead to vision loss.
- Meth: Talc particles from injecting meth can make their way to the retina and block small blood vessels, leading to vision loss.
- Opiates: Frequent or chronic use increases exposure to contaminants (like from needles), which increases the risk of serious eye infections and retinal damage.
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