How Do Drugs Affect Your Eyes: Redness, Dilated & Pinpoint Pupils

Eyes Wide Exposed: How Do Drugs Affect Your Eyes

Unveiling the impact, risks, and vision for a drug-free future

Abusing drugs can cause several negative side effects affecting both mental and physical health. One consequence of severe or chronic substance abuse is changes in vision, including pupil size, the colour of the whites and vision function. Over time, substance abuse can result in a number of eye conditions, including permanent vision loss. 

Different types of drugs affect the eyes differently, so this article will start off by discussing the various ways different groups of drugs impact the eyes. The article will also look at which drugs increase pupil size, why pupils dilate and how people may attempt to cover up these changes. 

The article will also explore some of the long-term eye damage caused by substance abuse, and treatment for drug-related eye issues and finish up by looking at where to go from here if you’re ready to seek support. 

Your Pupils on Drugs: Specific Substances


Stimulants are a group of drugs that speed up the messages between your brain and body. Also known as uppers, taking stimulants can make a person feel more energetic, confident and alert. This can cause your body to increase its heart rate, blood pressure and blood glucose levels. 

Stimulants include drugs like cocaine and amphetamines. Some people have been prescribed stimulants, such as methylphenidate, particularly for conditions like ADHD and narcolepsy. 

But what impact does taking stimulants have on your pupils? Abuse of stimulants commonly causes pupils to dilate. In addition, stimulant abuse over time can lead to level damage and jaundice, which can cause the skin and whites of the eyes to turn yellow.

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Opiates and Opioids

Opiates are a narcotic analgesic, derived from an opium poppy, whereas opioids are a synthetic form of narcotic analgesic. Both are powerful types of painkillers which can also cause the user to feel euphoric. Examples include heroin, morphine and codeine

This class of drugs is highly addictive and addiction can take hold over a very short period of time. As well as being used recreationally, some are available on prescription for chronic or severe pain. In recent years there has been an effort to reduce the number of prescriptions, due to the risk of addiction. The latest data shows in the last four years GPs and pharmacists have helped cut opioid prescriptions in England by 450,000. 

But what do they do to your pupils? Opiates cause pupils to contract, which is also known as miosis. Small pupils, sometimes described as pinpoint pupils, which don’t change in response to lighting can be a sign of an overdose. Like stimulants, abuse over the long term can lead to liver damage and jaundice, resulting in yellowing whites of the eyes. 


Depressants slow down the central nervous system, causing a delay in the messages between your brain and body. This can result in lower levels of concentration, coordination and ability to respond appropriately. In smaller doses, they can cause feelings of relaxation. 

Because they slow everything down, they are sometimes referred to as downers. Common types of depressants include alcohol and benzodiazepines. Some people are prescribed depressants, such as diazepam, for conditions including anxiety and insomnia. 

Taking depressants can cause a change in vision including double or blurry vision. Abuse can also cause dilated pupils, which is a sign of an overdose. 


Hallucinogens are a type of drug renowned for shifting a person’s perspective and sense of reality. Common forms of hallucinogens include LSD, also known as acid, and psilocybin, more commonly referred to as mushrooms. 

Research as to their utility as medicine is ongoing, but at present most hallucinogens are not prescribed and are instead used recreationally. 

Taking hallucinogens can result in several changes to vision including hallucinations as well as pupil dilation. There are case studies of permanent pupil changes following psychedelic substance use, including LSD and psilocybin. 


Dissociatives are a type of psychedelic drug. As the name implies, they cause the user to feel separate or detached from their body or surroundings. They can also cause other changes including hallucinations, changes to emotions and consciousness. 

Dissociatives work by changing how the brain’s receptors for glutamate work, this receptor impacts brain function and pain perception. Examples of dissociatives include ketamine and PCP. 

Dissociatives can have an effect on vision and pupils. For example, ketamine can cause rapid, involuntary eye movements and dilated pupils, both of which are a sign of intoxication. PCP can cause similar rapid eye movements, though someone intoxicated on PCP may be unresponsive to visual stimuli, instead staring blankly ahead. 

Research has found evidence that glutamate NMDA receptor activation is involved in generating the human pupillary light reflex, which could explain some of these effects.

how do drugs affect your eyes


Inhalants refer to drugs that are inhaled for the brief feeling of euphoria that is produced. Often these are everyday household items, such as glue and paint fumes, but they can include medical treatment, such as entonox which is made up of nitrous oxide and oxygen and is commonly used as a pain relief measure during hospital procedures and as women in labour. 

Abuse of inhalants, like paint thinner or recreational nitrous oxide, can cause your eyes to water and turn red. Both of these are a sign of intoxication. 


Consuming cannabis can cause a reaction similar to hallucinogens, however, it is a separate category as it also produces depressant-like effects. Also called weed, hash, and marijuana, cannabis can be consumed in many ways, including smoked and eaten. 

Since estimates began, cannabis has consistently been the most used drug in England and Wales. The latest data found 16.2% of people aged 16 to 24 years reported having used the drug in the last year.

Abusing cannabis can result in bloodshot eyes, which is one of the telltale signs that someone is ‘stoned’ or intoxicated.

Drugs That Cause Dilated Pupils

Dilated pupils happen when the black centre of the eye increases in size. Pupils naturally change size in response to various environmental changes, such as light or emotional events.

Using certain recreational drugs can also result in dilated pupils. Some of the most common recreational drugs which can dilate pupils include:

  • Stimulants e.g. cocaine
  • Depressants e.g. alcohol
  • Hallucinogens e.g. LSD 
  • Dissociatives e.g. ketamine 

Certain prescribed drugs can also lead to dilated pupils too. Some of the most common forms of medication that result in increased pupil size include anticonvulsants, antidepressants, antihistamines, benzodiazepines, decongestants, prescribed stimulants and selective serotonin reuptake inhibitors (SSRIs).

Why Do Pupils Dilate?

The iris sphincter and the iris dilator are the two muscle groups in the eye responsible for dilating the pupil. And it is the body’s nervous system which controls these. The parasympathetic nervous system is in control of body processes when you’re at rest, and this triggers the sphincter response. The sympathetic nervous system controls the body’s responses in fight-or-flight mode and that is responsible for triggering action in the dilator.

Usually, pupils change in size in response to how much light there is in the environment. When you go from inside to outside in direct sunlight, you’ll notice your pupils get smaller to limit the amount of light entering. Likewise, your pupils will also shrink when you focus on a nearby object. Pupils increase in size or dilate, in darker environments. They can also dilate in response to adrenaline, sexual arousal or migraines, head trauma or an eye injury. Certain medications and drugs can also impact the size of pupils. 

Attempts to Cover for Changes in the Eyes or Vision

Many people are aware that drug abuse can result in eye problems, whether that’s bloodshot eyes or dilated pupils. Some people attempt to cover this up by using eye drops. Other vision problems caused by drug abuse, such as blurry or double vision, can cause a person to focus intently to try and hide this symptom. However, vision changes and disturbances are usually tricky to hide and often a clear sign that someone has been abusing substances. 

Long-Term Eye Damage Caused By Substance Abuse

  1. Cornea damage: Certain drugs, including cocaine, can result in a type of inflammation of the cornea known as keratitis. This can eventually result in infectious ulcers in the corneas and corneal perforation.
  2. Dry eye syndrome: Inability to form tears, constant dry eyes and eyes that feel irritated frequently can happen in response to long-term alcohol abuse. 
  3. Glaucoma: Long-term increases in intraocular pressure can cause glaucoma, which is a change in the fluid pressure in the eye. Alcohol abuse is a common risk factor for substance-induced glaucoma.
  4. Ocular bone damage: Chronic drug use that involves snorting substances can damage the tissues around the sinuses, causes septal perforation, or extreme damage to the tissue between nostrils. Damage can also continue to the ocular ridge bones.
  5. Jaundice: Long-term use of substances including stimulants, opioids and alcohol can damage the liver and lead to cirrhosis and jaundice. This causes the white of the eyes to turn yellow. 
  6. Endophthalmitis: Sharing contaminated needles can cause microorganisms to spread through the bloodstream to the eye. This can cause endogenous endophthalmitis which can result in vision loss. 

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Double Vision

There is good evidence for the link between sustained drug abuse and the development of eye problems. This can include double vision, also known as diplopia, which is when a person can see two of everything. While it is often short-term, it can persist. Treatment for diplopia includes corrective lenses, eye coverings, eye exercises and surgery. 

Can Eye Damage From Substance Abuse Be Corrected?

The answer is, it depends on the level of damage sustained and the specific eye condition experienced. Some conditions can be corrected, but others may be permanent. According to research, substance abuse can lead to everything from mild eye symptoms to severe loss of vision, including endophthalmitis which can cause permanent loss of sight.

Hallucinogen Persisting Perception Disorder (HPPD)

Most commonly seen with LSD, HPPD is often called flashbacks. This condition results in sudden and often repetitive recurrences of the changes experienced during LSD use. 

Toxic Cataracts

Abusing substances over the long term can cause cataracts. Cataract development has been associated with alcohol abuse. Research suspects that the two are linked via a mechanism of metabolic byproducts, such as acetaldehyde, which reacts with and modifies lens proteins causing opacification of the crystalline lens.

In many cases, the first line of treatment for a vision problem caused by substance abuse is to stop the substance abuse and access treatment for the underlying addiction. It sounds straightforward, but without removing the trigger (i.e. the substance), it is impossible to improve your eye health. For people dealing with addictions, this means undergoing a detox.

How To Get Help For A Drug Addiction

Chronic substance abuse can result in all sorts of long-term health complications, including causing eye conditions. If you are facing vision issues because of substance abuse, substance abuse treatment can help. 

The exact type of treatment you offer will depend on your specific addiction, but it could involve medically assisted detox, inpatient or outpatient rehab, 12-step programs and therapy

If you, or someone you care about, is suffering from vision problems because of substance abuse and wants to get better, it’s important to know that help is available. If you’d like to discuss this with our friendly team, we’d be delighted to talk you through the next steps: 041 214 5111

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