How Long Do Your Pupils Stay Dilated When High? A Detailed Guide

September 24, 2025 •

4 min read

Pupil dilation, medically known as mydriasis, can be a common physiological response to a variety of factors, including the use of recreational substances. The answer to how long do your pupils stay dilated when high? is not a simple one, as it depends on the specific drug, dosage, and an individual's unique metabolism.

Quick Summary

The period for which pupils remain dilated after substance use is not fixed and is significantly influenced by the type of drug, the amount consumed, and individual body chemistry. For many stimulants and hallucinogens, dilation can last for several hours, with some effects lasting 12 hours or more, whereas cannabis-induced changes are typically shorter.

Key Points

Duration Varies: The length of time pupils stay dilated when high is highly dependent on the type of substance used.
Substance Matters: Effects range from a few hours for cannabis to 12+ hours for potent hallucinogens or multiple days for anticholinergic medications.
Beyond Drugs: Pupil dilation can also be caused by emotions, lighting, prescription eye drops, and serious medical conditions like head injury or stroke.
Metabolism is Key: Individual factors such as dosage, method of use, body weight, and metabolism influence how long the effects last.
Seek Medical Help: If dilated pupils are accompanied by severe headache, confusion, or balance issues, it could signal a medical emergency.
Manage Symptoms: To alleviate discomfort, wear sunglasses to combat light sensitivity and allow time for the substance to be metabolized.

Understanding the Science of Pupil Dilation

To understand why and for how long your pupils stay dilated when high, it's essential to know the basic mechanics of how your pupils function. The size of your pupils is controlled by two tiny muscles within the iris, the colored part of your eye: the sphincter pupillae and the dilator pupillae.

Sphincter Pupillae: This muscle is controlled by the parasympathetic nervous system and is responsible for making the pupil smaller (constricting) in bright light.
Dilator Pupillae: This muscle is controlled by the sympathetic nervous system, also known as the "fight or flight" response, and is responsible for widening the pupil (dilating) in low light or during moments of stress or arousal.

Many drugs interfere with this delicate balance. Stimulants, for example, often trigger the sympathetic nervous system, causing the dilator muscle to overwork, while hallucinogens can disrupt serotonin pathways, which also impact pupillary response. Substances that are central nervous system depressants, such as opioids, have the opposite effect and cause pinpoint pupils.

Factors Influencing the Duration of Dilation

Several key factors determine how long drug-induced pupil dilation will last:

The Substance Used

As mentioned, different classes of drugs have different impacts on the nervous system, and therefore, vary in their effects on pupils:

Cannabis (Marijuana): Pupil size changes are often minimal compared to other substances, and redness is more commonly associated. Any dilation is typically short-lived, with effects on the eyes subsiding in about three to four hours.
Stimulants (Cocaine, MDMA, Amphetamines): These drugs significantly increase sympathetic nervous system activity. Pupil dilation can be very noticeable and last for many hours, well after the initial euphoric effects have faded.
Hallucinogens (LSD, Psilocybin): Hallucinogens are known to cause pronounced mydriasis. The duration can be quite long, often lasting as long as the drug's psychological effects, which can be 6 to 12 hours or more.
Anticholinergics: Found in some over-the-counter medications and certain toxic plants (like belladonna), these drugs can cause pupil dilation that can last for several days.

Dosage and Purity

The amount of a substance consumed directly correlates with the intensity and duration of its effects. Higher doses or more potent forms of a drug will generally lead to more pronounced pupil dilation that lasts for a longer period of time. Purity also plays a role, as a more concentrated substance will have a stronger, more lasting impact.

Individual Metabolism

Every person's body processes substances differently. Factors such as age, weight, genetics, and overall liver health can affect how quickly the body metabolizes and eliminates a drug. A faster metabolism means the drug and its effects on the pupils will subside more quickly.

Route of Administration

How a substance is consumed also influences the timeline. Smoking or injecting a drug results in a rapid onset of effects, including pupil dilation. However, these effects may also wear off more quickly than if the drug were ingested orally, such as with edibles or pills, which can have a slower onset and a longer duration of action.

Comparison of Dilation Effects by Substance


Substance	Typical Dilation Duration	Primary Mechanism of Action
Cannabis	Minimal to moderate; ~3-4 hours	THC reduces intraocular pressure and can cause vasodilation.
Stimulants (e.g., Cocaine)	Pronounced; several hours	Increase sympathetic nervous system activity, overriding normal pupil control.
Hallucinogens (e.g., LSD)	Pronounced; 6-12+ hours	Disrupt serotonin pathways in the brain, affecting pupillary control.
Anticholinergics	Long-lasting; several days	Block acetylcholine, a neurotransmitter that constricts pupils.
Opioids (e.g., Heroin)	Constricted (Pinpoint pupils)	Stimulate opioid receptors that override normal pupillary reflex.

Non-Drug Causes of Mydriasis

While drug use is a common cause of dilated pupils, it is important to remember that it is not the only one. Other reasons for mydriasis include:

Emotional Responses: Strong emotions like attraction, fear, or anxiety can trigger the sympathetic nervous system, leading to temporary dilation.
Low Light Conditions: This is the most natural cause. Pupils widen to let in more light so you can see better in the dark.
Medical Conditions: Certain neurological issues, head injuries, and even migraines can cause one or both pupils to dilate irregularly.
Prescription Medications: Eye drops used during an eye exam or certain prescription drugs can cause temporary dilation.

Risks and When to Seek Medical Attention

Beyond the social implications, drug-induced pupil dilation carries some risks. Increased sensitivity to light (photosensitivity) is common and can be uncomfortable. It can also cause blurred vision and difficulty focusing on near objects.

It is critical to seek immediate medical attention if dilated pupils are accompanied by any of the following symptoms:

Severe headache
Confusion or altered mental state
Loss of balance or coordination
Vision loss or persistent blurry vision
Signs of a head injury

These symptoms, especially when pupils are severely dilated and unresponsive to light, could indicate a medical emergency such as drug toxicity, head trauma, or a stroke.

How to Help Your Pupils Return to Normal

For mild, temporary dilation, there are a few simple steps you can take to alleviate discomfort:

Reduce Bright Light: Wear sunglasses, even indoors, to protect your eyes from discomfort caused by light sensitivity.
Stay Hydrated: Drinking plenty of water can help your body metabolize the substance faster.
Rest and Wait It Out: For drug-related dilation, time is the most effective remedy. Giving your body time to process the substance is key.

For further reading on the broader topic of substance use and health, a good resource is the National Institute on Drug Abuse (NIDA).

Conclusion

Ultimately, the question of how long do your pupils stay dilated when high? has a complex answer that depends on many variables. While it's a temporary effect for most substances, understanding the underlying cause and the various influencing factors is important for personal health and safety. Always be aware of the signs of a more serious medical issue and do not hesitate to seek professional help if needed.

Frequently Asked Questions

There is no instant way to make drug-induced pupil dilation go away. The pupils will return to normal size only after the substance has been metabolized and eliminated from the body. You can manage the effects by wearing sunglasses to reduce light sensitivity and resting in a calm, dimly lit environment.

No, not all substances cause pupil dilation. For example, opioids are known to cause pinpoint pupils (constriction). Other drugs, like cannabis, may cause only slight or temporary dilation, while others have a much more pronounced effect. The effect depends entirely on the drug and the individual.

The primary dangers include extreme light sensitivity, blurred vision, and difficulty focusing, which can impair activities like driving. Severely dilated pupils that do not react to light can also be a sign of a medical emergency like drug overdose, head trauma, or brain injury.

Stimulants, like cocaine and MDMA, typically cause significant pupil dilation by activating the sympathetic nervous system. In contrast, depressants like opioids generally cause pupil constriction, leading to very small, or 'pinpoint,' pupils.

Prolonged and severe drug abuse, especially of hallucinogens and anticholinergics, can potentially lead to lasting changes in pupillary function, although cases of permanent dilation are rare. In most cases, the effect is temporary, resolving as the drug leaves the system.

It can be difficult to tell the exact cause without more information. Other potential causes include certain prescription medications, neurological issues, eye injuries, or simply low ambient light. It is often necessary to consider the full context of symptoms and recent activities to determine the cause.

While certain substances like caffeine can cause minor, temporary dilation due to their mild stimulant effects, it is not a common or significant side effect. Foods and typical supplements are highly unlikely to cause the level of mydriasis seen with recreational drug use.

If your pupils are dilated for a medical eye exam, the effect can last anywhere from 4 to 24 hours, depending on the type of drop used and individual response. This is different from drug-induced dilation, but the temporary effects are similar.