Conjunctivitis: Is It Bacterial, Viral or Allergic?

What is conjunctivitis?

Conjunctivitis, often called "pink eye", is inflammation of the conjunctiva, the thin clear layer covering the white of the eye and the inside of the eyelids. It is very common and usually mild. Most cases get better on their own within a week or two, but the cause matters because it influences how you treat it.

The three main types

• Viral conjunctivitis: the most common type, often alongside a cold. It is contagious and usually clears without specific treatment.
• Bacterial conjunctivitis: caused by bacteria, sometimes producing more sticky discharge. It is also often self-limiting.
• Allergic conjunctivitis: triggered by allergens such as pollen or dust, affecting both eyes and linked to other allergy symptoms. It is not contagious.

Our overview of bacterial infections explained can help you understand the bacterial type in more detail.

Telling them apart

No single sign is definitive, but these clues can help:

• Watery discharge and a recent cold point more towards viral
• Thick, sticky, yellow-green discharge that makes eyelids stick together can suggest bacterial
• Itchy, watery eyes with sneezing or a runny nose suggest an allergic cause
• Allergic and viral conjunctivitis often affect both eyes; bacterial may start in one

A pharmacist or doctor can help confirm the type if you are unsure.

Treating conjunctivitis

Most infective conjunctivitis, whether viral or bacterial, improves without antibiotics. Self-care is usually enough:

• Gently clean away discharge with cooled boiled water and clean cotton wool
• Use lubricating or artificial tear drops to ease discomfort
• Apply a cool, damp cloth to soothe the eyes
• Remove contact lenses until the eye is fully better

Antibiotics only target bacteria, so they do nothing for viral or allergic conjunctivitis. Where a bacterial infection is troublesome or persistent, a pharmacist or doctor may recommend antibiotic eye drops or ointment. Allergic conjunctivitis is instead managed with antihistamines or other allergy treatments. You can browse the antibiotics range to understand the kinds of products used for confirmed bacterial infections, and using them appropriately helps limit antibiotic resistance explained.

Stopping it spreading

Viral and bacterial conjunctivitis are contagious, so good hygiene helps protect others:

• Wash hands often and avoid touching or rubbing the eyes
• Do not share towels, flannels or pillows
• Avoid eye make-up until the infection clears
• Wash hands after applying any drops

When to see a doctor

Seek medical advice if you have:

• Eye pain, rather than mild discomfort
• Sensitivity to light or changes in your vision
• Intense redness in one or both eyes
• A baby under 28 days old with red, sticky eyes
• Symptoms that do not improve after a couple of weeks

These features can suggest a more serious eye problem that needs proper assessment.

General information only — not medical advice. Always read the patient information leaflet and consult a doctor or pharmacist before starting any medication.