“Pink eye” (conjunctivitis) is an inflammation of the thin membrane over the white of the eye. It is common and usually mild. But a red eye has many causes, and some of them threaten vision. Studies have found that antibiotic drops are often prescribed for red eyes that are not bacterial infections at all.
Conditions that are often mistaken for pink eye
Allergic conjunctivitis. Both eyes itch, water and look pink, often with sneezing and a runny nose, and seasonal timing. It is not contagious and antibiotics do not help; antihistamine eye drops do.
Dry eye. Burning, gritty feeling, redness that worsens with screens, wind or air conditioning. Common with age, contact lenses and some medicines.
Blepharitis. Inflamed eyelid margins with crusting at the lashes, especially in the morning. It is chronic and treated with lid hygiene.
Subconjunctival hemorrhage. A bright red patch from a broken blood vessel, painless, often after coughing or straining. It looks alarming but usually clears in one to two weeks.
Foreign body or corneal abrasion. A scratch or particle causes pain, tearing and a feeling that something is in the eye.
Serious conditions that need prompt care
- Keratitis (corneal infection), especially in contact lens wearers: pain, light sensitivity, blurred vision, sometimes a white spot on the cornea. Bacteria, fungi or amoeba can cause permanent damage within days.
- Uveitis or iritis: inflammation inside the eye, with deep aching pain, light sensitivity and redness around the colored part of the eye. Sometimes linked to autoimmune conditions.
- Acute angle-closure glaucoma: sudden severe eye pain, headache, nausea, halos around lights and blurred vision. This is an emergency.
- Herpes eye infections (herpes simplex or shingles near the eye).
- Scleritis: severe, boring pain and deep redness.
Red flags: see an eye doctor the same day
- Moderate or severe eye pain
- Blurred vision that does not clear with blinking
- Strong sensitivity to light
- Contact lens wearer with a red, painful eye (remove the lenses and do not put them back)
- A rash on the forehead or nose tip with a red eye
- Injury, chemical exposure, or a red eye in a newborn
When it probably is pink eye
Typical viral conjunctivitis: watery discharge, gritty feeling, often starting in one eye then the other, sometimes with a cold. Bacterial conjunctivitis: thicker yellow-green discharge that glues the lids in the morning. Vision stays normal and pain is mild. Wash hands often and avoid sharing towels.
The American Academy of Ophthalmology’s pink eye page describes the types and treatments.
