Pink eye (conjunctivitis) is an inflammation or infection of the transparent membrane (conjunctiva) that lines your eyelid and covers the white part of your eyeball. When small blood vessels in the conjunctiva become inflamed, they’re more visible. This is what causes the whites of your eyes to appear reddish or pink.
Pink eye is commonly caused by a bacterial or viral infection, an allergic reaction, or — in babies — an incompletely opened tear duct.
Though pink eye can be irritating, it rarely affects your vision. Treatments can help ease the discomfort of pink eye. Because pink eye can be contagious, early diagnosis and treatment can help limit its spread.
Causes of pink eye include:
- A chemical splash in the eye
- A foreign object in the eye
- In newborns, a blocked tear duct
Viral and bacterial conjunctivitis
Viral conjunctivitis and bacterial conjunctivitis may affect one or both eyes. Viral conjunctivitis usually produces a watery discharge. Bacterial conjunctivitis often produces a thicker, yellow-green discharge. Both viral and bacterial conjunctivitis can be associated with colds or with symptoms of a respiratory infection, such as a sore throat.
Both viral and bacterial types are very contagious. They are spread through direct or indirect contact with the eye secretions of someone who’s infected.
Adults and children alike can develop both of these types of pink eye. However, bacterial conjunctivitis is more common in children than it is in adults.
Allergic conjunctivitis affects both eyes and is a response to an allergy-causing substance such as pollen. In response to allergens, your body produces an antibody called immunoglobulin E (IgE). This antibody triggers special cells called mast cells in the mucous lining of your eyes and airways to release inflammatory substances, including histamines. Your body’s release of histamine can produce a number of allergy signs and symptoms, including red or pink eyes.
If you have allergic conjunctivitis, you may experience intense itching, tearing and inflammation of the eyes — as well as sneezing and watery nasal discharge. Most allergic conjunctivitis can be controlled with allergy eyedrops.
Conjunctivitis resulting from irritation
Irritation from a chemical splash or foreign object in your eye is also associated with conjunctivitis. Sometimes flushing and cleaning the eye to rid it of the chemical or object causes redness and irritation. Signs and symptoms, which may include watery eyes and a mucous discharge, usually clear up on their own within about a day.
The most common pink eye symptoms include:
- Redness in one or both eyes
- Itchiness in one or both eyes
- A gritty feeling in one or both eyes
- A discharge in one or both eyes that forms a crust during the night that may prevent your eye or eyes from opening in the morning
When to see a doctor
Make an appointment with your doctor if you notice any signs or symptoms you think might be pink eye. Pink eye can be highly contagious for as long as two weeks after signs and symptoms begin. Early diagnosis and treatment can protect people around you from getting pink eye too.
People who wear contact lenses need to stop wearing their contacts as soon as pink eye symptoms begin. If your symptoms don’t start to get better within 12 to 24 hours, make an appointment with your eye doctor to make sure you don’t have a more serious eye infection related to contact lens use.
In addition, there are other serious eye conditions that can cause eye redness. Typically, these conditions will also cause pain and blurred vision. If you experience these symptoms, seek urgent care.