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Signs of Opioid Use in the Eyes: Pinpoint Pupils & Redness

Peter Manza, PhD profile image
Reviewed By Peter Manza, PhD • Updated Aug 13, 2023 • 5 cited sources

Some of the signs of opioid use that are easy to notice are changes in pupil size and redness of the eyes. Though this alone is not an indication of drug misuse or an opioid use disorder (OUD), in the context of other clues, it can be an additional indicator that someone may be misusing substances. 

How Do Pupils Change While on Opioids?

Though opioids are prescribed to help patients manage pain, they are highly addictive and can be misused. Whether they are used medicinally or misused by someone struggling with OUD, they evoke physiological changes in the body that can be observed by others.

The two most noticeable ways that opioids impact the eyes visibly are miosis (pupil constriction, a phenomenon that occurs when the black center of the eyes gets smaller) and eye redness. 

Miosis may occur to varying degrees when opioids are used. Sometimes, the pupil gets so small that the irises, or colored part of the eye, look huge.

This happens because the opioids bind to receptors like the mu opioid receptor, which causes the pupillary sphincter muscle to activate.[1] This muscle controls how large or small the pupil is in order to manage the amount of light taken into the eye. During opioid use, this muscle contracts regardless of environmental exposure to light and constricts the pupils.

This is usually one of the most immediately noticeable signs of opioid use.

How Else Do Eyes Change in Appearance Due to Opioid Use?

Redness in the eyes is another common sign of opioid use. It may be a result of several factors, including change in blood flow to the eyes, irritation from smoke or other substances, and changes in tear production. 

Opioids can cause the blood vessels in the body to expand, including those in the eyes, leading to increased blood flow and redness. The dilation of the blood vessels can also lead to decreased oxygen levels in the tissues, which can cause inflammation and irritation, further contributing to the redness. [2]

In addition to the dilation of blood vessels, opioids can also cause eye redness by decreasing tear production. The lacrimal gland in the eye produces tears, which help keep the eye lubricated and free of debris. 

Opioids can inhibit the activity of the parasympathetic nervous system, which controls tear production, resulting in dry eyes. When the eye is dry, the tissues can become irritated and inflamed, leading to redness and discomfort.

Additionally, because heavy opioid use can cause drowsiness, someone under the influence of the substance may have heavy eyelids or difficulty keeping their eyes open.[3] It is one of the characteristics associated with nodding out, a term that describes how someone might appear to almost fall asleep when opioids are at peak levels in the body. 

Are There Different Eye Changes Due to Use of Specific Opioids? 

Yes, not all opioids cause miosis to the same degree. In general, opioids with a high affinity for the mu opioid receptor, such as morphine and fentanyl, tend to cause significant miosis.[4] Other opioids, such as methadone and buprenorphine, may cause miosis to a lesser degree or not at all. 

The presence or absence of miosis can also depend on tolerance to opioids and other factors, such as the dose and route of administration.

It’s important to note that not everyone will experience extreme pinpoint pupils or redness of the eyes when misusing opioids, no matter the type. It is also true that not everyone with pinpoint pupils and/or red eyes is misusing their prescription for painkillers or even experiencing the issue due to drug use. 

In fact, someone taking methadone for the treatment of opioid use disorder may experience some change in pupil size and eye redness even though they are taking the medication as prescribed. This is important for family members to remember, particularly if they are watchfully on the lookout for signs of relapse and concerned that eye changes may be an indicator of a return to active substance misuse. 

Everyone is different. Genetics and environmental factors can impact how someone’s eyes will respond to the use of any opioid. 

How Else Does Opioid Use Impact the Eyes?

Long-term use and misuse of opioids can contribute to a number of ocular disorders, including thrombotic thrombocytopenic purpura (TTP), diffuse retinal ischaemia, and disc neovascularization, according to a review of the literature published in the Indian Journal of Medical Research.[5]

Get Help for Opioid Misuse & OUD 

Problems with the eyes are just one of many issues that can develop with ongoing use and misuse of opioid drugs, both prescription and illicit. If someone you love is having a hard time managing their prescription healthfully or is misusing street drugs like heroin, treatment can help. 

Medication for Addiction Treatment (MAT) is considered the gold standard in treatment for OUD. With the help of a medication like Suboxone and therapy, people effectively learn to manage their OUD, so they can live a healthy and happy life in recovery.

Reviewed By Peter Manza, PhD

Peter Manza, PhD received his BA in Psychology and Biology from the University of Rochester and his PhD in Integrative Neuroscience at Stony Brook University. He is currently working as a research scientist in Washington, DC. His research focuses on the role ... Read More

  1. Pupillary Effects of High-Dose Opioid Quantified With Infrared Pupillometry. Anesthesiology. November 2014. Accessed March 2023.
  2. Relationship Between Retinal Blood Flow and Arterial Oxygen. The Journal of Physiology. December 2015. Accessed March 2023.
  3. Opioids and Stimulants: What Are They and How Are People Using Them? University of Washington, Addictions, Drug & Alcohol Institute. Mar 2022. Accessed March 2023.
  4. Mu Opioids and Their Receptors: Evolution of a Concept. Pharmacological Reviews. October 2013. Accessed March 2023.
  5. Illicit Drugs: Effects on Eye. Indian Journal of Medical Research. September 2019. Accessed March 2023.

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