Types of conjunctivitis: allergic, bacterial and viral
There are three main types of conjunctivitis:
There are also numerous, less-common forms of conjunctivitis, including:
Giant papillary conjunctivitis
Many types of conjunctivitis share symptoms with other types of pink eye. Individually, however, each has its own set of causes, risk factors and treatments.
This is the most common type of conjunctivitis, and what doctors are often referring to when they use the term “pink eye.”
Since viral conjunctivitis is caused by a virus, usually an adenovirus, it is extremely contagious. It can be contracted when respiratory droplets transfer to the eye (through sneezing or coughing) or by touching your eye before washing your hands. It can also accompany a cold, flu or other upper respiratory infection.
Viral conjunctivitis usually starts in one eye (unilateral) before eventually infecting both (bilateral). Common signs include itchy, red eyes with clear, watery discharge.
The condition usually goes away by itself after a short time, but medicated pink eye drops are often prescribed or advised. Antibiotic eye drops aren’t effective against the viruses that cause viral conjunctivitis, but other drugs may be used to ease symptoms.
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Another common condition, bacterial conjunctivitis, is caused by bacteria and is also highly contagious.
Unlike the watery discharge of viral pink eye, bacterial conjunctivitis produces a thick white, yellow or green discharge from the affected eye(s).
Pink eye caused by bacteria usually clears up by itself within a duration of one to two weeks, but may need antibiotic eye drops if the condition worsens. Antibiotic pink eye remedies are usually recommended if:
The infection is severe
The patient has a weakened immune system
The infection does not start to clear up on its own within a week
Sexually transmitted diseases like gonorrhea and chlamydia (gonococcal and chlamydial conjunctivitis) can also cause bacterial pink eye, but this is much less common.
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Eye allergies can lead to a common, non-contagious reaction called allergic conjunctivitis. It can be triggered by allergens like pollen, animal dander and dust mites.
The most prominent allergic conjunctivitis symptoms are itchy and red eyes. These can be alleviated with antihistamine eye drops or pills that control allergic reactions.
The condition can be seasonal or year-round, depending on your individual allergies. When possible, avoiding the allergen in question is an important factor in preventing or getting rid of allergic conjunctivitis.
Giant papillary conjunctivitis
This type of pink eye most commonly affects people who wear soft contact lenses. It may cause contact lens intolerance, itching, a heavy discharge, tearing and red bumps on the underside of the eyelids.
It usually affects both eyes.
People affected by giant papillary conjunctivitis will be asked to stop wearing their contacts for a period. An eye doctor may recommend switching to a different type of contact lens to reduce the chance of conjunctivitis returning.
Newborns can also be exposed to sexually transmitted diseases when they pass through the birth canal of a mother with an active infection. These infections can transfer to a newborn with a unique form of neonatal pink eye.
Gonococcal conjunctivitis, stemming from the gonorrhea bacteria, is one of these infections. With modern treatment, it can often be avoided by administering medicine immediately after birth.
If you are pregnant and may have a sexually transmitted disease, a doctor will recommend getting it checked and treated before the birth of your baby.
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Chemical pink eye (Toxic conjunctivitis)
The chemicals in the things we’re exposed to can sometimes cause a unique type of conjunctivitis.
Mild irritants can include cigarette smoke, diesel exhaust, perfumes and certain eye drops, along with other chemicals. Symptoms of chemical pink eye, sometimes called toxic pink eye, include pain, eye redness, vision changes and significant swelling around the eyes.
More serious chemicals or irritants may require immediate treatment. If you think you have chemical conjunctivitis, contact a medical professional as soon as possible.
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Treating your pink eye
While not all types of conjunctivitis require treatment, some can develop into more serious conditions without it.
An eye doctor will be able to correctly diagnose your type of conjunctivitis and provide you with any treatment necessary.
Page published in August 2020
Page updated in March 2022