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Red eye is quite a common symptom, which can occur because of several reasons. The redness is due to vasodilatation or bleeding.

Causes for red eye

  • staying awake late
  • prolonged close work
  • drinking alcohol
  • dry eyes
  • conjunctivitis
  • foreign object in the eye
  • allergy
  • UV light
  • chemical irritation
  • subconjunctival haemorrhage (sugillation)
  • keratitis, scleritis or iritis
  • sudden increase in eye pressure

Itchy, watery or stinging eyes the feeling that there is something in your eye, and discharge are often symptoms of ophthalmitis. It can occur in one or both eyes. Allergic conjunctivitis usually occurs during the pollen season or in the proximity of certain animals.

Subconjunctival haemorrhage (sugillation) may happen without an obvious cause and may sometimes be due to strenuous physical exercise, rubbing the eye or a minor trauma. A bright red area can be seen in the eye, covering the white part partially or completely. Hypertension can cause recurrent sugillations. Red eye may also be due to an illness affecting the sclera (the white part), the iris (the coloured part) or the cornea (the transparent front part) of the eye. In these cases, the redness is apparent all around the cornea, and the eye is sore and sensitive to light. Vision may also be impaired.   

Red eye and remedies

If the cause of the red eye is obvious (staying awake late, close work, temporary irritation or alcohol), no treatment is necessary. Redness can be relieved with vasoconstricting eye drops that can be purchased from a pharmacy and used for a couple of days. However, these eye drops should not be used if the reason for the red eye is dryness of the eyes.

Symptoms of obvious allergic conjunctivitis can be alleviated with antihistamines and other allergy eye drops, which can be purchased from a pharmacy without a prescription.

Subconjunctival haemorrhages (sugillations) do not require treatment if no trauma is involved and if the eye is not sore. Redness will disappear spontaneously in a couple of weeks.

When to seek medical treatment

Red eyes that are clearly not caused by staying awake late, temporary irritation or alcohol always require a medical examination to find the reason. It is also recommended to seek professional help if subconjunctival haemorrhages are recurrent.  

If red eye is accompanied by a sudden deterioration in vision, or if the eye hurts, seek medical care immediately.

Data sources: Duodecim: Terveysportti health portal, Lääkärin tietokanta doctor’s database
FSHS General practitioner / 23 June 2023