Overview
The conjunctiva is the transparent film covering the white of the eye and the inside of the lids. When it becomes inflamed, its blood vessels dilate and the eye looks pink or red. The cause matters: most cases are viral and self-limiting, bacterial cases may need antibiotics, and allergic cases need neither.
Viral conjunctivitis is highly contagious and often follows a cold. It typically starts in one eye and moves to the other a few days later.
What are the common symptoms?
- Pink or red eye, usually with a gritty feeling rather than deep pain
- Watery discharge (viral), thick yellow-green discharge and lids stuck shut in the morning (bacterial), or itching and swelling (allergic)
- Swollen lids
- A tender lymph node in front of the ear, in viral cases
- Vision that stays essentially normal
What causes it, and who is at risk?
- Viruses — most commonly adenovirus, often alongside a cold
- Bacteria, more common in young children
- Allergy: pollen, dust mites, pet dander
- Irritants: chlorine, smoke, chemical splash
- Contact lens wear, particularly with poor hygiene
How is it treated?
The first job is telling the types apart, and telling all of them apart from the serious causes of a red eye.
- Viral: cold compresses, lubricating drops, scrupulous hand hygiene, and time — typically one to two weeks
- Bacterial: antibiotic drops or ointment where indicated
- Allergic: antihistamine or mast-cell stabiliser drops, and avoiding the trigger
- Stop contact lens wear until the eye is fully settled, and replace lenses and case
- Do not share towels or pillows; wash hands frequently
When to get seen quickly
A red eye with significant pain, reduced vision, marked light sensitivity, or a hazy cornea is not simple conjunctivitis. Those signs point to conditions that can threaten sight — get seen the same day. The same applies to any red eye in a contact lens wearer.
This page is general information, not a diagnosis. Only an eye care professional who has examined you can tell you what is actually going on.