Drugs and Dilated Pupils: Causes and Risks

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Drugs and Dilated Pupils: Causes and Risks

There are various signs of drug use, one of the most common being dilated pupils. Law enforcement and medical professionals often deal with substance abuse, and the extent to which pupils are dilated is considered an indicator of drug use. How big the pupils are when they’re dilated can even help to determine which drug was used. Today, our holistic treatment center in Lake Worth is looking into the relationship between drugs and dilated pupils.


Why Do Pupils Dilate on Drugs?

Pupils are the black circles in the center of your eyes. Their function is to let light in and direct light to your retina, the nerves at the back of your eyes, so you can see.

The muscles in the colored part of your eye – the iris – control the size of your pupil. The opening of the iris occurs when two muscle groups in the eye are activated: the iris sphincter and the iris dilator.

The body’s parasympathetic nervous system, which controls your bodily responses to stress, triggers the sphincter receptor. The sympathetic nervous system, which controls your body’s fight-or-flight response, triggers an action in the dilator.

Usually, how large your pupils are depends on how much light you’re exposed to. In low light or in a dark room, your pupils expand to let more light in, but in brighter or well-lit areas, your pupils may constrict or become smaller to let less light in.

But your pupils on drugs is a whole different story. Some drugs affect both the parasympathetic and sympathetic nervous systems, triggering the body’s fight or flight adrenaline response by interacting with serotonin and adrenergic receptors in the central nervous system. As a result, mydriasis occurs, which is when the muscle relaxes and allows the eye’s pupil to expand and let in more light.


Drugs That Dilate Pupils

Psychotropic drugs can have a large effect on both the parasympathetic and sympathetic nervous systems, depending on the specific type of drug used. Plenty of drugs work on the central nervous system to affect pupil dilation.

The most common drugs that cause pupil dilation include:

  • SSRI antidepressants
  • Amphetamines
  • MDMA (Ecstasy)
  • Psilocybin
  • LSD
  • Cocaine
  • Mescaline
  • Opioids


When it comes to using drugs and dilated pupils, serotonin agonizes 5-HT2A receptors in the brain, producing dilation. Benzodiazepines like Xanax can also cause pupil dilation because they stimulate GABA, a neurotransmitter with a muscle-relaxing effect.

Stimulant medications like Adderall and Ritalin may also cause the pupils to dilate because of their effects on serotonin and other chemicals in the brain. To put it simply, drugs affect the muscles in the eyes, impacting their ability to control how much light they let in. Since many drugs alter the chemical balance in the brain, your pupils’ reaction to light may be altered.

With that said, pupil dilation, although a common indicator of drug use, is a poor way to assess sobriety. As a result, officials also look for other signs of drug use – such as heavy sweating, dry mouth, and mood swings – to determine whether the person is high and the type of drug they used.


Pupil Dilation Side Effects and Risks

If you’ve ever gone to an optometrist to get your vision checked, then you may recall the discomfort of having your pupils dilated. To do this, the doctor usually puts dilating drops in the eyes. This is a common aspect of getting your eyes checked because it opens up the eye and allows doctors to check for any underlying issues.

At the moment, pupil dilation can be extremely uncomfortable and usually comes with side effects like:

  • Heightened sensitivity to light
  • Blurry vision
  • Trouble focusing on objects


For someone who experiences pupil dilation on drugs, their risk of injury and accidents increases not only because of other side effects of drug use but also because their vision is compromised. Although blurred vision is usually harmless in the long term, the effects of drugs on the eyes are more extensive, usually resulting in blindness.


Help for Drug Addiction

If there’s a suspicion of drug use, there’s a tool that helps determine the type of drug based on the amount of pupil dilation called the “Drug Recognition Card.” This chart shows images of pupils reacting to different drugs. This chart is mostly used by law enforcement and emergency medical teams.

The Drug Recognition Card is based on standards set by the International Association of Chiefs of Police (IACP) and helps first responders determine the type of drug used (categories include depressants, stimulants, hallucinogens, phencyclidine, narcotics, inhalants, and cannabis) based on the pupil diameter. The chart also details other reactions, such as state of pupil dilation and reaction to light, to assess which drug was used.

In the end, drugs can affect the eyes as well as other parts of the body in more ways than one. Chronic drug and alcohol abuse can affect your physical health, as well as your mental state, relationships, career, finances, and more. The good news is that sobriety changes your body and your life in the best way possible.

If you or someone you care about has developed a drug or alcohol use disorder, our treatment center in Palm Beach offers all the resources needed to achieve a sober lifestyle. From medically monitored detox to substance-specific treatment programs, patients will receive one-on-one guidance through every step of their recovery.


For more information about our addiction treatment in Palm Beach, call Behavioral Health of the Palm Beaches today at 561-220-3981.


Related Reading:

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Does One Drink Break Sobriety?

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