Dilated Eyes? 9 Possible Causes

Blonde woman prone to dilated eyes

Tiny muscles in the colored part of your eye control your pupil’s size. The iris is the colored part of your eye, and it controls how much light enters your eye. A normal, healthy iris expands and contracts to allow more light in if it’s dark and less light when the conditions become brighter. Pupils that get dilated expand to an abnormal size and often refuse to contract.

Normal pupils in younger adults may be 2 to 4 millimeters wide in bright conditions and expand to almost 8 millimeters in very dark states. Pupil size varies a little, but those numbers indicate an average size. Older adults may see their pupils shrink a little with age making it harder to see in dark situations, but the change is often so minor it doesn’t affect eyesight.

Several things may cause pupils to dilate including some medications and medical disorders. While a dilated pupil is a symptom of a condition called anisocoria, it’s not the same thing as dilated pupils, but the two get confused with each other quite often. People suffering from anisocoria may end up with two pupils of varying sized whereas dilated pupils tend to mirror each other’s size.

​The Likely Culprits Behind Your Dilated Eyes

Yellow eyes which is likely to become dilated eyes

Alcohol may cause your pupils to dilate or react slowly to changes in the light. If you often have a few drinks after work or on the weekend and just noticed your eyes widening, wait until the alcohol wears off and see if they return to normal. If they still refuse to contract and expand correctly, consider the following medications since they may cause dilated pupils, they include:

  • Decongestants
  • Antidepressants
  • Anti-seizure medications
  • Anti-nausea medications
  • Botox medications or treatments
  • Atropine
  • Antihistamines
  • Drugs for motion sickness

Eyeglasses for dilated eyes

Always consult your doctor before stopping or starting any medication whether it’s prescribed or over the counter drugs. Some of the medicines above may save your life. Talk to your doctor if they put you on new medications that seem to cause dilated pupils. They may swap you to a different type of drugs or have some advice on ways to treat the dilation. Either way, always talk to your doctor about drugs.

If you just started taking some new drugs and your pupils dilate, it’s pretty easy to figure out the medication is the culprit. However, some of the drugs on our list may cause dilated pupils months after you start taking them instead of right away. This is why we stress talking to your physician or pharmacists. Either person will tell you if the side effects include dilated pupils.

You probably need to ask your doctor about non-prescription medications as well, especially if you take any of the medicines on the list that requires a prescription just to stay safe. If you suspect a pill that you picked up off the shelf is causing your pupil problems, it’s probably safe to stop taking those drugs and see if the issue ends.

Another problem you may experience is drugs reacting poorly to other medications if you start taking something new. For instance, if you take motion sickness medication and it’s never caused your pupils to dilate, and your doctor recently prescribed an antidepressant, the two drugs may not play well together. Ask your doctor or pharmacist to confirm and seek alternative remedies.


Eyes prone to dilated eyes

Any injury to the eye that includes damage in or around the iris may cause dilation at the time of the accident or years later if scar tissue gets in the way. A number of eye surgeries including cataract and glaucoma surgery. Some eye surgeries carry a fair amount of risk, so ask your doctor about possible side effects before having a procedure done.

Benign episodic unilateral mydriasis which often comes with or before a migraine may cause pupil dilation. If you experience severe headaches with pain behind your eyes, this condition may explain your dilated pupils and blurry vision. In some cases, the pupil dilation and blurry vision that comes with this disorder may last twelve hours or longer. Talk to your doctor about treatment if this is common.

On a side note about benign episodic unilateral mydriasis; young women experience this disorder more often than older women or men of any age. Older women and men may experience this condition, but it’s more common in younger women. When the headaches leave, the symptoms usually dissipate, and your pupils should return to normal without treatment unless your experience this problem often.

Adie’s pupil, sometimes called tonic pupil, is actually a neurological disorder that causes one pupil to grow larger than the other one. The condition is rare, but it may be the cause of dilated pupils. Unfortunately, a cure for Adie’s pupil doesn’t exist at the time of this writing. Also, what causes Adie’s pupil is a mystery, but head trauma, infections, and some surgeries may cause the disorder.

Some brain injuries such as blunt force trauma or piercing of the brain may cause your pupils to dilate permanently. Injuries usually cause only one pupil to dilate, and your doctor probably discussed this with you if you’ve injured your brain. That said, a concussion may not require immediate medical attention if you’re not aware you have one. If you suspect an untreated injury, talk to your doctor.

A random dilated pupil or pupils that seem mysterious may be a sign you have a neurological disorder or brain tumor. If you suddenly find your pupils dilate without cause, consult your doctor right away because you may suffer from an untreated brain injury or a tumor. Getting up to fast and banging your head on a cabinet door or other minor head injuries may hurt your brain. Get it checked out.

​Self-Inflicted Causes for Dilated Pupils

dilated eye peeping at a hole

We don’t have any proof, but alcohol may end up as the chief cause for random pupil dilation. However, if you consume enough to cause pupil dilation, it’s doubtful you’ll notice pupil dilation, and it’ll wear off as the alcohol wears off. This is the primary reason we didn’t count alcohol as one of the causes for dilated pupils, but we felt it needed mentioning and a little explanation anyway.

Recreational drug use sort of falls into the same category as alcohol but some drugs leave you more aware of your surroundings than others. However, LSD, Ecstasy, cocaine, and amphetamines may heighten your senses but also cause pupil dilation in many cases. We don’t have a complete list of recreational drugs, but if you partake in any, either stop or talk to your doctor about side effects.

Sexual arousal or even mild attraction may cause your pupils to dilate. Pupils dilate during sex, or when we look at people, we find attractive. The change in your iris may go unnoticed, but it’s there nonetheless. It’s rare but not unheard of for pupils to remain dilated after sex for a few hours. If your pupils get stuck after sex in an enlarged state often, talk to your doctor about possible causes for this.

Bonus: Possible Solutions or Cures for Dilated Pupils

Woman holding an eyeglass for dilated eyes

It may sound like a broken record but seek medical attention if the cause for your dilated pupils is not readily determined or if someone else notices them before your vision changes. If you know motion sickness drugs or decongestant medications affect your pupils, you may not need to worry as much. That said, talk to your doctor or pharmacists to see if they have any advice or alternatives.

Some medical conditions or drugs cause pupils to dilate, and there’s little you can do about it. You may end up stuck with the problem until your doctor takes you off the medication of your condition is cured. However, people that wear eyeglasses may need to try a simple remedy and switch to photochromic lenses. These lenses lighten and darken automatically based on the amount of light hitting them.

Your pupils can’t control themselves, or your medications inhibit full control of your iris, so photochromic lenses do the work for them. They’ll limit the amount of light that enters your eye and may help reduce headaches and nausea that often come with pupil dilation problems.  Talk to your eye doctor and find out if these lenses could solve your problem.

If you know you’re stuck with a dilated pupil and worry about the way it looks, talk to your eye doctor about cosmetic contact lenses. Your doctor may call them prosthetic contact lenses. These contact lenses cover up the pupil and make it less noticeable. The only drawback is you may need one for each eye to make your eyes match. Wearing contact lenses isn’t for everyone.


shown dilated eyes of a covered woman's face

We listed nine possible causes for pupil dilation above. We considered reactions to prescribed or over the counter medications as one cause since it seemed like one definition with some sub-definitions. Sudden or random pupil dilation may be scary and cause problems driving, so seek medical attention if it happens a lot. Your doctor knows your medical history and may find other causes or concerns.

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