Common causes of a painless red eye

The most likely causes ofa painless red eyeare minorproblems such as conjunctivitis ora burst blood vessel. These conditionsdon't tend to affect your vision andnormally get better within a week or two.


Conjunctivitis is inflammation (swelling and irritation) of the conjunctiva the thin layer of tissue covering the eyeball and inner surfaces of the eyelids.

This causes the blood vessels on the eye to swell, makingone or botheyes look bloodshot and feel gritty.

Other symptoms can include itchiness and watering of the eyes, and a sticky coating on the eyelashes.

Conjunctivitis can be caused by an infection, an allergy (for example, to pollen), oran irritant, such as chlorine or dust.

Treatment will depend on what is causing the condition. Sometimes notreatment is needed, because it may get better on its own.

Your doctor mayrecommend:

  • regularly cleaning away any crusting or discharge
  • not wearing contact lenses until the condition passes
  • washing your hands regularly and avoiding sharing pillows or towelsto help prevent the condition spreading to others (if it's infectious)
  • antibiotic eye drops for bacterial infections or medications, such as antihistamines for allergies

This is called a subconjunctival haemorrhage.

It can look alarming, especially if you're taking medication such as aspirin or warfarin (these reduce the blood's ability to clot, which can exaggerate the redness), but it's not usually serious and should clear up on its own within a few weeks.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018