Pink eye is an inflammation (redness) of the conjunctiva, the clear tissue that lines the inside surface of your eyelid and outer coating of your eye. This tissue helps keep your eyelid and eyeball moist. You can get pink eye from viruses, bacteria, allergens and other causes.

Symptoms of pink eye include:

• Redness in the white of your eye or inner eyelid.
• Increased tearing.
• Thick yellow discharge that crusts over your eyelashes, especially after sleep.
• Green or white discharge from your eye.
• Gritty feeling in one or both eyes.
• Itchy eyes (especially in pink eye caused by allergies).
• Burning eyes (especially in pink eye caused by chemicals and irritants).
• Blurred vision.
• Increased sensitivity to light.
• Swollen eyelids.

Only your healthcare provider can diagnose you for sure, but there are a few symptoms to look for that are characteristic of pink eye. You probably have pink eye if the white of your eye is light pink to reddish all over and it:

• Is constantly tearing.
• Has a green, yellow or white discharge.
• Itches.

The pink or reddish color of pink eye happens when the blood vessels in the membrane covering your eye (the conjunctiva) gets inflamed, making them more visible. Causes of inflammation include:

• Viruses. Viruses are the most common cause of pink eye. Coronaviruses, such as the common cold or COVID-19, are among the viruses that can cause pink eye.
• Bacteria. Common types of bacteria that cause bacterial conjunctivitis include Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumonia and Pseudomonas aeruginosa.
• Allergens. This includes molds, pollen or other substances that cause allergies.
• Irritating substances. This includes shampoos, cosmetics, contact lenses, dirt, smoke and pool chlorine.
• Sexually transmitted infections (STIs). A virus (herpes simplex) or bacteria (gonorrhea or chlamydia) can cause STIs. STIs can cause pink eye in both adults and newborns.
• A foreign object in your eye.
• Blocked or incompletely opened tear ducts in babies.
• Autoimmune conditions. Diseases that cause your own immune system to overreact are a rare cause of pink eye.

Your ophthalmologist or pediatrician will examine your eyes or your child’s eyes. Your provider can usually diagnose pink eye based on symptoms and health history. You may do an acuity test (eye chart test) to check your vision. Tell your healthcare provider if you have:

• Had a viral or bacterial infection recently.
• Allergies.
• Gotten anything irritating (like chemicals or foreign objects) in your eye recently.
• Been exposed to a sexually transmitted infection.
• A family history of autoimmune disease or other reason to think you have an autoimmune disease.