Conjunctivitis, which people often refer to as pinkeye, is an inflammation of the membrane covering the eye. It usually resolves on its own without medical attention, but anyone concerned about their symptoms should contact a doctor.

Conjunctivitis is an inflammation of the conjunctiva, the clear membrane covering the eye. A person with conjunctivitis may notice that the white part of their eye has become swollen. It may bulge out and appear jelly-like.

If a bacterial or viral infection causes conjunctivitis, the infection can easily spread to other people.

However, not all cases are contagious. Conjunctivitis can also result from allergies, exposure to chemicals, or contact lens wear. A mild case may clear up on its own, but a person may wish to call a doctor if they have concerns.

This article discusses conjunctivitis in more detail, including the symptoms, causes, and treatments.

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The conjunctiva is a clear membrane that covers the inside of the eyelids and the white part of the eye.

The irritation or infection of this membrane results in a condition called conjunctivitis.

The irritation may cause the conjunctiva to swell and become jelly-like. It also causes blood vessels in the conjunctiva to widen, increasing blood flow and making the white of the eye appear red or pink.

This effect is the reason why many people refer to conjunctivitis as pinkeye.

The Centers for Disease Control and Prevention (CDC) note that the common symptoms of conjunctivitis are:

  • redness or pinkness in the white of one or both eyes
  • swelling of the clear coating of the eye
  • itching or burning eyes
  • watery eyes
  • the feeling of having something in the eye
  • discharge of pus or mucus
  • crusty eyelids or lashes, especially when waking up
  • discomfort when wearing contact lenses

A person’s symptoms may vary depending on what is causing their conjunctivitis. For example, the CDC says that pinkeye resulting from a bacterial infection produces a thick discharge from the eye, whereas in viral infections, the discharge is usually watery.

Someone whose conjunctivitis is due to an allergy may have very itchy eyes, along with other allergy symptoms, such as coughing, sneezing, or a sore throat.

Although there are many possible causes of conjunctivitis, the most common are viruses, bacteria, and allergens.

Viral infection

A variety of viruses may cause conjunctivitis. One of those is adenovirus, which often produces symptoms similar to those of the common cold.

Viral conjunctivitis is highly contagious and can result in large outbreaks.

Bacterial infection

Bacterial conjunctivitis is more common in children than in adults and occurs more often between December and April. The condition spreads easily to other people.

Allergies

Substances that can produce an allergic reaction may also cause conjunctivitis.

These substances include:

  • pollen from trees, grasses, or weeds
  • pet dander
  • dust mites
  • molds
  • cosmetics
  • contact lenses and lens solution

People who have other allergic conditions, such as asthma or hay fever, commonly develop allergic conjunctivitis.

Chemicals

The American Optometric Association states that chemicals are a possible cause of conjunctivitis because they can irritate the eye. Examples include chlorine in swimming pools and chemicals in air pollution.

Anyone who accidentally splashes a harsh chemical in their eye should flush the eye extensively with water and then contact a doctor.

Contact lens wear

If wearing contact lenses is causing a person to develop conjunctivitis, their optometrist may suggest switching to a different type of lens or using an alternative disinfectant solution.

Thyroid eye disease

Another possible cause of conjunctivitis is thyroid eye disease.

People sometimes develop this condition if they have Graves’ disease, which is an autoimmune disorder that causes an overactive thyroid.

Other names for thyroid eye disease are Graves’ ophthalmopathy and Graves’ eye disease.

The American Thyroid Association notes that the symptoms of Graves’ eye disease include:

  • red or inflamed conjunctiva
  • swollen eyelids
  • a gritty feeling in the eyes
  • dry eyes or excessive tears
  • light sensitivity
  • bulging eyes
  • double vision

Foreign object

A foreign object that becomes stuck in the eye can cause redness and discharge that may continue for 12–24 hours after its removal.

Other infections

Fungi, ameba, and parasites are among the other possible causes of conjunctivitis.

The diagnosis of conjunctivitis may require several steps. These include:

  • Patient history: A doctor may ask what symptoms a person is having and when they started. They may also wish to know whether any health or environmental factors might be contributing to the condition.
  • Eyesight test: A doctor may check to see whether the condition has affected the person’s vision.
  • Bright light and magnification: This approach allows the doctor to examine the conjunctiva and other eye tissue.
  • Lab tests: A doctor might take cultures or smears of conjunctival tissue, especially if the condition does not resolve with treatment.

The cause of person’s conjunctivitis is likely to be viral if it occurs around the same time they have a common cold or respiratory tract infection.

Similarly, bacterial conjunctivitis may occur when someone has an ear infection because the same bacteria can cause both conditions.

Pinkeye often goes away on its own. Viral conjunctivitis is usually mild and typically clears up within 1–2 weeks without treatment.

A mild case of bacterial conjunctivitis may get better in 2–5 days without antibiotic treatment and clear up completely in about 2 weeks.

A doctor may prescribe an antibiotic if a person’s eye is producing a lot of discharge or if certain bacteria are causing the infection.

In other cases, people may find that home treatment helps relieve the symptoms. They can try:

  • taking an over-the-counter pain reliever
  • using lubricating eye drops
  • placing a damp washcloth over the eyes for a few minutes several times a day, using a clean washcloth each time
  • avoiding known allergens that are causing the condition

A person who wears contact lenses should stop wearing them until the condition clears up.

An individual should also stop wearing eye makeup while they have an eye infection. Once it has cleared, they can help prevent reinfection by replacing the products with new ones.

Someone with conjunctivitis should avoid using eye drops to reduce redness, such as tetrahydrozoline (Visine), as they could cause discomfort.

The CDC recommends calling a doctor if conjunctivitis occurs with any of the following symptoms:

  • blurry vision
  • light sensitivity
  • eye pain
  • intensely red eyes
  • worsening symptoms or lack of improvement

A person who has a weakened immune system or a preexisting eye condition should contact a doctor if they develop conjunctivitis.

Parents or caregivers should call a doctor right away if a newborn has symptoms of conjunctivitis.

Conjunctivitis, or pinkeye, is a common eye condition that often results from a bacterial or viral infection or a reaction to an allergen.

Conjunctivitis is not usually serious, and it generally goes away on its own. Home remedies may help relieve the symptoms.

A person with bacterial or viral conjunctivitis can help prevent the condition from spreading by washing their hands often, avoiding touching their eyes, and refraining from sharing personal items, such as pillows or towels, with others.