Opioids usually make a person’s pupils constrict. This is when the black part at the center of the eye gets smaller, reducing the amount of light that gets inside.

Typically, pupil constriction happens in bright light, but certain drugs can cause it to happen, too. This includes opioids, or narcotics.

Opioid drugs come from the poppy plant and act on the brain to provide pain relief. They include prescription medications, such as those containing oxycodone (OxyContin) and hydrocodone (Vicodin), as well as codeine, morphine, and some illegal drugs, such as heroin.

Pinpoint-sized pupils can be a sign of opioid use and can also help a healthcare professional confirm a diagnosis of an opioid overdose when they occur with other signs. If you think someone may be experiencing an overdose, call 911 right away.

This article explores how opioids affect the pupils, the impact on long-term eye health, and how to get help for opioid misuse.

Close up of an eye with constricted pupils due to opioids.Share on Pinterest
Opioids can cause the pupils to become very small. Joana Rodrigues/EyeEm/Getty Images

Usually, the pupils change size in response to light, getting larger in low light and smaller in bright light. But opioids can cause pupillary constriction, or miosis. This means the pupils at the center of the eye become very small and may stop responding to changes in light levels.

Many factors can cause the pupils to get larger, such as stimulant medications, injury, and migraine. But few factors make pupils constrict. As a result, constricted pupils can indicate opioid use.

How opioids constrict the pupils

When opioids enter an individual’s system, they attach to opioid receptors in the brain and change how the nervous system works.

Doctors divide the human nervous system into the central nervous system (CNS), which consists of the brain and spinal cord, and the peripheral nervous system (PNS), which is the network of nerves outside the CNS.

The PNS has two divisions:

  • The somatosensory nervous system: This system is how people sense touch, pressure, and where their body is in space.
  • The autonomic nervous system: This system contains the sympathetic nervous system, which stimulates bodily functions such as breathing and heart rate, and the parasympathetic nervous system, which slows down various functions.

Opioids stimulate the parasympathetic nervous system. In the process, the pupils become smaller as the circular iris sphincter muscle contracts. Changes in eye movement may also occur, as well as drooping eyelids.

Although each person’s experience with drug misuse is unique, some general signs and indicators may be present in someone who has an opioid use disorder.

Behavioral signs may include:

  • avoiding family or friends
  • changing friends or mixing with new people
  • losing interest in activities
  • rapid mood changes
  • isolation or secretive behavior
  • lower grades at school or impaired performance at work
  • financial hardship

The physical signs could include:

  • tiredness or drowsiness
  • increase or decrease in appetite
  • weight loss or gain
  • wearing long sleeves or hiding the arms
  • flu-like symptoms, such as sweating and shaking
  • constipation

A person living with someone with an active opioid addiction may also notice:

  • missing medications
  • missing shoelaces or belts, which a person may use to find veins for drug injection
  • equipment for opioid use around the house, such as syringes, bags with powder residue, and missing or burnt spoons

Opioids can cause effects such as drowsiness, mental fog, and digestive system upset. If someone overdoses on opioids, it is a medical emergency that can have fatal consequences. Therefore, if anyone presents with the following signs of an overdose, it is essential to call 911:

  • slow or absent breathing or heartbeat
  • an extremely pale face that may feel clammy
  • limp limbs and body
  • a purple or blue tinge to the fingernails or lips
  • vomiting
  • making gurgling noises
  • inability to speak or otherwise respond
  • appearing unconscious
  • pinpoint pupils

The symptoms may start with drowsiness and smaller pupils that do not react to light. They may progress to pinpoint pupils, loss of consciousness, and an inability to breathe.

Pinpoint pupils do not indicate opioid overdose on their own, but if a person has other signs of an overdose, they can help healthcare professionals confirm the diagnosis.

If a person does not receive treatment, an opioid overdose can cause death.

Although opioid use disorder can cause serious health and social problems, treatment and recovery are possible. Drug rehabilitation programs can help a person withdraw from the drug, overcome any personal issues that might motivate drug use, and get their life back on track.

Seeking help is the most critical step on the route to recovery. A qualified healthcare professional, such as a doctor, psychiatrist, psychologist, or nurse, can assess the individual and develop a treatment plan to suit their needs.

The treatment plan may include:

  • Appointments: A person may need to make regular visits to a treatment center or healthcare professional for ongoing assessments and individual or group counseling.
  • Medications: Many people receive medication alongside counseling. Options include methadone, buprenorphine, and naltrexone. These medications do not create a new addiction when a person uses them according to the prescription.
  • Commitment: The individual will need to agree to cooperate fully with treatment, which involves keeping all appointments, agreeing to drug testing, taking medications as a doctor has prescribed them, and refraining from using drugs without a prescription.
  • Information: It is important for the individual to understand the risks of relapse and other safety concerns.

The long-term use of opioids can have a wide range of effects, including damage to the eyes. Opioid misuse may result in:

  • Eye infections: With the rise in opioid use, there has also been a rise in a rare and severe form of eye infection known as endogenous endophthalmitis. A 2020 study in the United States found a 400% increase in drug use-related hospitalizations due to this infection between 2003–2016.
  • Vision loss: Endogenous endophthalmitis is a severe condition that is treatable with antibiotics. However, permanent vision loss is common if left untreated.

Although overcoming opioid use disorder is challenging, people can find help and support as they navigate their journey back to health. The solidarity and advocacy that the following organizations provide can help improve the chances of a successful recovery:

Smaller, constricted pupils can indicate opioid use. When a person uses opioids, the parasympathetic nervous system causes the iris to contract, making the pupils small. As a result, the pupils may no longer respond to light. Additionally, the pupils may move differently, and the eyelids may droop.

Opioid use disorder can lead to serious health consequences, including eye damage, but recovery is possible. If an individual is concerned about opioid use, they should seek medical attention. A doctor can put together a suitable treatment plan and help the individual find sources of support.