Condition

Conjunctivitis

Also known as Pink Eye, Red Eye, Viral Conjunctivitis, Bacterial Conjunctivitis, Allergic Conjunctivitis

Updated May 16, 2026For educational purposes only. Not a substitute for medical advice. See our terms.

Bottom Line

Conjunctivitis (pink eye) is when the clear skin over the white of your eye gets red and puffy. Most cases are from a virus or allergies and clear up on their own, but some need drops or other care from an eye doctor.

Conjunctivitis is one of the most common eye problems in the world. It is the reason for about 1 out of every 100 visits to primary care doctors and one of the top reasons people go to the eye doctor 1.

The conjunctiva is the thin, see-through layer that covers the white of the eye and the inside of the eyelids. When it gets irritated, the tiny blood vessels in it swell and the eye looks pink or red. There are three main kinds of conjunctivitis: viral, bacterial, and allergic. Knowing which kind you have changes the treatment 2.

Most cases get better on their own in 1-2 weeks. But some red eyes are not simple conjunctivitis at all — they are emergencies like a chemical splash, a herpes infection, or acute angle-closure glaucoma. The hard part is knowing the difference 3.

Symptoms & Warning Signs

Common symptoms of conjunctivitis are:

  • Pink or red eye — one or both eyes
  • Watering or discharge — clear and watery (viral), thick and yellow or green (bacterial), or stringy mucus (allergic)
  • Itching — especially with allergic conjunctivitis
  • Gritty feeling — like sand in the eye
  • Crusty eyelids in the morning — bacterial pink eye often glues the lids shut overnight
  • Swollen eyelids
  • Mild blurry vision that clears when you blink
A red eye is not always pink eye. Go to the emergency room or seek urgent eye care if you have:
  • Severe eye pain
  • Any loss of vision or vision that does not clear with blinking
  • A chemical splash in the eye
  • A red eye in a baby less than 28 days old
  • A red eye after an eye injury, or a contact lens you cannot remove
  • Light sensitivity with a deep, throbbing pain
These can mean a corneal ulcer, herpes infection, acute glaucoma, or other serious problem.

What Causes Conjunctivitis

There are three main kinds of conjunctivitis, plus some less common ones 3:

  • Viral conjunctivitis (most common). Usually caused by the same viruses that cause colds (adenovirus is the most common). Very contagious. Spreads by touching your eye after touching a doorknob, towel, or person with the virus 4.
  • Bacterial conjunctivitis. More common in children. Bacteria like staph, strep, or Haemophilus cause thick yellow or green pus and crusty eyelids. Also contagious 5.
  • Allergic conjunctivitis. Not an infection and not contagious. Triggered by pollen, pet dander, dust mites, or mold. Usually both eyes, very itchy 6.

Less common causes include:

  • Chemical or irritant conjunctivitis — from smoke, chlorine, fumes, or anything splashed in the eye. A chemical splash is an emergency.
  • Contact lens-related conjunctivitis — including giant papillary conjunctivitis and serious lens-related infections.
  • Newborn conjunctivitis (ophthalmia neonatorum) — a red eye in a baby less than 28 days old can be caused by chlamydia, gonorrhea, or herpes from birth, and can cause blindness if not treated 7.

Things that raise your risk:

  • Living or working with people who have pink eye
  • Having a cold or sore throat
  • Wearing contact lenses, especially overnight or for too many hours
  • Hay fever, eczema, or asthma
  • Close contact with young children, daycare, or schools
  • Touching your eyes with unwashed hands

Treatment

Treatment depends on the kind of conjunctivitis you have 2.

Viral conjunctivitis:

  • There is no antibiotic that kills the virus. It clears up on its own in 1-2 weeks.
  • Cool compresses and artificial tears can help with itching and grittiness.
  • Wash hands often and do not share towels, pillowcases, or eye makeup. The virus is contagious for up to 2 weeks.
  • Antibiotic drops do NOT help viral pink eye and add no benefit 1.

Bacterial conjunctivitis:

  • Many mild cases clear up on their own in about a week.
  • An eye doctor may prescribe antibiotic eye drops or ointment to clear it faster and lower the chance of spreading 5.
  • Contact lens wearers with a red eye always need to be seen — it could be a more serious lens-related infection.

Allergic conjunctivitis:

  • Avoid the trigger when possible (close windows during pollen season, wash bedding often).
  • Cool compresses and artificial tears help calm symptoms.
  • Over-the-counter or prescription antihistamine eye drops are the main treatment 6.
  • For severe cases, eye doctors may use mast cell stabilizers or short courses of stronger drops.
What does not work: Putting breast milk, urine, or honey in the eye. Using old leftover antibiotic drops from a past illness. Sharing a friend's prescription drops. Using "red-eye relief" drops with vasoconstrictors for more than a day or two.

How to Prevent Spreading Pink Eye

Viral and bacterial conjunctivitis spread very easily. To protect yourself and others:

  • Wash your hands often with soap and water, especially after touching your eyes or face.
  • Do not touch or rub your eyes, even when they itch.
  • Do not share towels, pillowcases, washcloths, or eye makeup with anyone while you have pink eye.
  • Throw out eye makeup used while you had pink eye — it can hold the germ.
  • Clean glasses with soap and water often.
  • Take out contact lenses if your eye is red. Replace lenses and the case once the infection is gone.
  • Stay home from school or work if your eye is very red or has heavy discharge, especially in the first few days.
  • Cover coughs and sneezes — viruses that cause colds also cause pink eye.

For allergic conjunctivitis, prevention is about your triggers: close windows on high-pollen days, shower after time outdoors, dust often, and use allergy medicines before the season starts if you know you are sensitive.

Common Questions About Conjunctivitis

Viral pink eye is usually contagious as long as the eye is red and watery — often up to 2 weeks. Bacterial pink eye is contagious until about 24 hours after starting antibiotic drops, or for a few days without them. Allergic conjunctivitis is not contagious at all.

Next Steps

  1. 1Wash your hands often with soap and water, and avoid touching or rubbing your eyes.
  2. 2Use cool compresses and preservative-free artificial tears to feel better while a mild red eye gets better on its own.
  3. 3Throw out eye makeup and clean glasses if you have pink eye, and replace contact lenses and the case after the infection clears.
  4. 4See an eye doctor if a red eye lasts more than a week, gets worse, or you wear contact lenses.
  5. 5Go to the emergency room for severe eye pain, vision loss, a chemical splash, a red eye in a newborn, or a red eye after eye injury.
  6. 6If you have hay fever, start your allergy medicine before pollen season and keep windows closed on high-pollen days.

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