Josh Chandler | May 28, 2024

What Drugs Cause Dilated Pupils?

Understanding Pupil Dilation

Mydriasis (dilated pupils) is called when the black center part of your eyes gets larger than normal. Pupils are round openings in the center of the iris with two sets of muscles, the sphincter and the dilator. These parts of your eyes allow light to reach the retina, so when you’re in dim lighting, they may expand to let more light in, and when you look toward a bright light, they’ll get smaller. They may also shrink as you look at something close to your face. These are all called “direct responses” as your pupil size changes to accommodate your vision. 

There are also various reasons a pupil will dilate that aren’t vision-related. It could happen due to an underlying medical issue, an eye injury, having eye drops put in, or even due to strong emotions, adrenaline, or sexual attraction. It can even happen temporarily when concentrating hard on a specific task. One of the biggest causes of unusually dilated pupils is drugs, and both illicit drugs and prescription medications can cause dilation. Substances that change your pupil size are known as anticholinergic, meaning they block neurotransmitters, which can affect how the parasympathetic nervous system responds to stimuli, including the light around you. The following article will explore what drugs cause dilated pupils and why.  


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Common Drugs That Lead to Pupil Dilation

Some of the most common drugs that cause dilated pupils are cocaine, MDMA (ecstasy), LSD (acid), methamphetamines, marijuana, ketamine, benzodiazepines, and psychedelic mushrooms. 

Stimulants and Pupil Dilation

Stimulants, including cocaine and amphetamines like meth, molly, MDMA, and ecstasy, can cause a variety of eye problems, including dilated pupils and blurred vision. Legal prescription stimulant medications like ADHD medication can also cause this. 

Pupil dilation happens because cocaine blocks the reuptake of dopamine. At the same time, amphetamines affect the sympathetic nervous system and serotonin levels in your system, which leads to the body producing a higher level of norepinephrine (also known as noradrenaline). The drugs cause your nervous system to go into a state of arousal, with increased energy levels and wider pupils. 

Hallucinogens and Their Effects on the Eyes

Hallucinogenic drugs like LSD, PCP, mescaline, psychedelic mushrooms, and ketamine can cause both pupil dilation and pupil constriction, depending on the person’s sensitivity to the substance and how much they’ve taken. Initially, the pupils will likely dilate, but as the hallucinogenic effects intensify, they may constrict. 

Prescription Medications That Can Cause Dilated Pupils

Some common prescription medications that cause dilated pupils are:

  • Antidepressant SSRI medications
  • Antihistamines
  • Decongestants
  • Anti-nausea medicine
  • Anti-seizure medication
  • ADHD medication
  • Atropine
  • Benzodiazepine medications
  • Parkinson’s disease medications

Other Substances Linked to Pupil Dilation

People may also experience dilated pupils from:

  • Botulinum toxin (aka Botox) is a neurotoxin used for cosmetic purposes, migraine treatments, and other conditions.
  • Mydriatic eye drops, the eyedrops used at your eye doctor’s office and during medical procedures, are designed to dilate the iris muscles for a short period, usually 4 to 8 hours.
  • Caffeine consumption may dilate pupils in some people and increase blood pressure in the eyes.
  • Drinking alcohol can relax eye muscles, causing the pupils to dilate.
  • Dramamine and other over-the-counter motion sickness medicines.
  • Sweat-blocking medications like Qbrexa.

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The Significance of Dilated Pupils in Diagnosis

Dilated pupils are not always a sign that a person is misusing drugs or suffering from drug addiction, but they can be an indicator, especially if they are exhibiting other signs of drug use like:

  • Changes in their hygiene or grooming habits.
  • Exhibiting signs of paranoia and anxiety.
  • Increased secrecy, lying, and other behavioral changes.
  • Changes in their sleep patterns and energy levels.
  • Lack of motivation or self-esteem.
  • Showing a lack of interest in their usual hobbies and activities.
  • Changes in their friend group or hangout spots.
  • Intense irritability, defensiveness, or mood swings.
  • Difficulty concentrating or paying attention.
  • Memory loss.
  • Engaging in risky behaviors or getting into legal trouble.
  • Poor work or school performance.
  • Relationship issues with friends and family.

Dilated pupils may be a symptom of a health condition, but if your loved one has a history of substance abuse or has been showing signs of addiction, including signs of opioid addiction, it may be time to talk to them about getting help. 

Health Risks Associated with Dilated Pupils

Dilated pupils can make you more sensitive to light and cause blurred vision, eye strain, and headaches. Suppose you wake up one morning with dilated pupils. In that case, if they change after a head injury, or if you notice your pupils are different than normal (i.e., one is dilated and the other is not) for any reason, it’s best to seek medical attention immediately. Irregular pupil dilation is not just associated with drug use; it can also be an indicator of a health problem. These include:

  • Eye injuries due to impact or chemical splashes
  • Head trauma
  • A blockage of blood flow to the nerves
  • Migraine (or ocular migraine, which does not present with a typical headache)
  • Stroke
  • Brain tumor

Horner’s syndrome can cause the pupils of one eye to constrict and the other to dilate. Third-nerve palsy can cause eye movement issues with one pupil bigger than the other. Adie’s Pupil Syndrome can lead to one pupil staying dilated much longer than the other while reacting slower to light changes. Anxiety and panic can also cause a person’s pupils to dilate as they go into “fight or flight” mode. 

If you’ve noticed abnormal pupil dilation in yourself or a loved one, seek medical attention. A doctor must evaluate the symptoms to determine the reason behind the dilated pupils. Never ignore any abnormal pupil dilation, as it could be a symptom of a serious health issue, a substance use disorder, or even an overdose. 


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Muse Treatment’s Approach to Substance Use and Recovery

At Muse Treatment Center, we are committed to creating a recovery program that will help you stop misusing substances but will also help you improve your quality of life, gain new healthy habits, and take control of your future. Substance use disorders can be complex issues, but through evidence-based therapy sessions, group therapy meetings, holistic healing, medication management services, and relapse prevention programming, amongst other treatments, you’ll have the opportunity to become the drug-free person you want to be. We get to know about you, your health, your history of drug and alcohol use, your preferences, and your recovery goals, and build a program around your unique needs, giving you the tools to make meaningful change. 

If you or a loved one would like to learn more about our drug and alcohol recovery programs, our inpatient rehab, partial hospitalization programs, and intensive outpatient programs, and how it all works, please call us today at 800-426-1818 or contact us online. You can speak confidentially with a knowledgeable counselor who can check your insurance coverage and tell you what to expect when you’re ready to proceed with treatment. We are here for you, and we can make addiction treatment work for you so you can heal your body, mind, and spirit on your own terms. 

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Josh Chandler
Josh Chandler
After growing up in Chicago and North Carolina, Josh chose to get help with substance use disorder and mental health in California because of the state's reputation for top-tier treatment. There, he found the treatment he needed to achieve more than five years of recovery. He's been in the drug and alcohol addiction rehab industry for four years and now serves as the Director of Admissions for Resurgence Behavioral Health. Josh remains passionate about the field because he understands that one phone call can alter the course of a person's life.

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