Pink eye, known medically as conjunctivitis, is inflammation of the thin, clear tissue that lines the inside of your eyelid and covers the white part of your eye. When that tissue gets irritated or infected, the tiny blood vessels inside it swell and become more visible, giving the eye its signature pink or red appearance. It’s one of the most common eye conditions, and about 80% of acute cases are caused by viruses.
The Four Types of Pink Eye
Not all pink eye is the same. The cause determines how it spreads, how long it lasts, and how it’s treated.
Viral pink eye is by far the most common type. Adenoviruses cause 65% to 90% of viral cases. Herpes simplex, herpes zoster, and enterovirus are less common culprits. Viral pink eye spreads easily through direct contact with infected eye secretions or contaminated surfaces, and it often shows up alongside a cold or upper respiratory infection.
Bacterial pink eye is caused by bacteria that can be passed through hand-to-eye contact, contaminated makeup, or shared towels. The usual organisms involved include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. In rarer cases, sexually transmitted bacteria like chlamydia or gonorrhea are responsible, and these require more aggressive treatment.
Allergic pink eye is not contagious at all. It’s your immune system overreacting to allergens like grass and tree pollen (seasonal), or to dust mites, pet dander, and mold spores (year-round). It tends to affect both eyes at once and often comes with sneezing or a runny nose.
Irritant pink eye happens when something physically or chemically irritates the eye: chlorinated pool water, soap, smoke, or a stray eyelash. Symptoms typically clear on their own within about a day once the irritant is removed.
How Symptoms Differ by Type
All forms of pink eye share some common features: redness in the white of the eye, swelling of the eyelids, a gritty feeling, tearing, and sensitivity to light. The key difference is in the discharge.
Viral pink eye produces a watery, thin discharge. Your eyes may be teary and uncomfortable, but you won’t usually see thick gunk building up overnight. Bacterial pink eye, on the other hand, produces thick pus that’s often yellow or green. This is the type most likely to glue your eyelids shut while you sleep, leaving a heavy crust on your lashes in the morning.
Allergic pink eye causes intense itching along with watery, swollen eyes. If itching is your dominant symptom and both eyes are affected, allergies are the most likely explanation. Irritant pink eye causes watering and sometimes a mucus-like discharge, but it resolves quickly once you’re no longer exposed to the irritant.
How It Spreads
Viral and bacterial pink eye are both contagious. They spread through direct contact with eye secretions, contaminated hands, or shared personal items like towels, pillowcases, and makeup. Pink eye generally remains contagious as long as the eye is still tearing and producing discharge.
Allergic and irritant pink eye are not contagious, since there’s no infectious organism involved.
How Pink Eye Is Diagnosed
Most of the time, a doctor can diagnose pink eye just by asking about your recent symptoms and looking at your eyes. No special tests are usually needed. In rare cases where symptoms are severe, where a sexually transmitted infection is suspected, or where there may be a foreign body in the eye, the doctor may take a small sample of the discharge for a lab culture.
Treatment for Each Type
Treatment depends entirely on what’s causing the inflammation.
Viral pink eye has no specific cure. Antibiotics do nothing against viruses, so treatment focuses on comfort while the infection runs its course. Cool compresses can help ease irritation, and artificial tears can relieve dryness. Most cases resolve on their own within one to three weeks.
Mild bacterial pink eye often clears up without treatment in 2 to 5 days, though it can take up to 2 weeks to fully resolve. Antibiotic eye drops or ointment may be prescribed to shorten the illness, reduce the risk of complications, and limit how long you’re contagious. Antibiotics are more likely to be recommended if there’s heavy pus discharge, if you have a weakened immune system, or if a more aggressive bacterium is suspected.
Allergic pink eye is managed with a combination approach. Antihistamine eye drops help with immediate relief, while mast cell stabilizer drops are used over a period of weeks to prevent the allergic reaction from recurring. Over-the-counter allergy medications can also help. For severe flare-ups, a doctor may prescribe short courses of anti-inflammatory drops. Avoiding the triggering allergen, when possible, is the most effective long-term strategy.
Irritant pink eye usually just needs flushing. Rinsing the eye with clean water or saline to remove the irritant is often all it takes, and symptoms typically resolve within a day.
Home Care That Helps
Regardless of the type, a few things can make pink eye more bearable while it heals. A clean, cool compress placed gently over closed eyes soothes itching and swelling, especially with allergic pink eye. A warm compress works better for loosening the crusty discharge that builds up with bacterial infections. Use a fresh washcloth each time and wash used cloths in hot water and detergent.
If you wear contact lenses, stop using them until symptoms are completely gone. Throw away disposable lenses and lens cases you used while infected, and clean reusable lenses thoroughly before wearing them again. The same goes for eye makeup: anything that touched your eyes during the infection should be replaced.
Preventing the Spread
Pink eye passes easily through households, schools, and workplaces. The single most effective prevention measure is handwashing with soap and water for at least 20 seconds, especially before and after touching your eyes or applying any drops. If soap isn’t available, hand sanitizer with at least 60% alcohol works as a substitute.
Beyond hand hygiene, a few specific habits make a real difference:
- Don’t share personal items. Towels, washcloths, pillowcases, eye drops, makeup, and eyeglasses can all carry the infection.
- Don’t touch or rub your eyes. If you need to clean discharge, use a fresh cotton ball or clean wet washcloth, then throw it away or wash it immediately.
- Keep infected and uninfected eyes separate. Don’t use the same eye drop bottle for both eyes.
- Wash bedding and towels frequently in hot water and detergent during an active infection.
- Avoid swimming pools while you have symptoms.
Pink Eye in Newborns
Pink eye in newborns is treated as a medical priority. Babies can pick up infections during delivery, and some of these infections can be serious. Chlamydial conjunctivitis can spread to a newborn’s lungs. Gonococcal conjunctivitis can progress to bloodstream infections, meningitis, or corneal ulcers that cause permanent blindness if untreated. Herpes viruses passed during birth can also cause severe eye damage. Any newborn showing signs of pink eye, including redness, swelling, or discharge, needs immediate medical evaluation.
Symptoms Worth Taking Seriously
Most pink eye is uncomfortable but harmless. However, certain symptoms suggest something more than routine conjunctivitis. Significant eye pain (not just irritation), blurred vision that doesn’t clear when you blink away discharge, extreme sensitivity to light, or symptoms that worsen instead of improving after several days all warrant a prompt visit to a healthcare provider. The same applies if only one eye is affected and the redness is intense, or if you wear contact lenses and develop symptoms, since contact lens wearers face a higher risk of corneal infections.