What should you know about sudden bloodshot eye?

Redness appears when tiny blood vessels on the white of the eye widen or leak. Dry air, dust, rubbing, contact lenses, coughing or a minor surface injury can trigger it. A sharply defined red patch with little discomfort may be a subconjunctival haemorrhage, which is blood beneath the clear surface rather than inside the eye. It can look dramatic while vision remains normal.

Itching and watering may fit Allergic Conjunctivitis, while sticky discharge and eyelid irritation can occur with Conjunctivitis. Redness with marked light sensitivity, a deep ache, nausea, injury or reduced vision is different and should not be managed only with home care.

Do not rub the eye. Remove contact lenses and avoid wearing them until the eye feels normal and a clinician has advised that it is safe. Rinse away a possible irritant with clean lukewarm water, and use a cool clean compress for irritation. Avoid sharing towels or eye cosmetics if discharge is present. Artificial tears may soothe dryness; do not use someone else’s prescription drops or leftover antibiotics.

Seek urgent medical care for sudden vision loss or blur, severe pain, strong light sensitivity, an irregular pupil, a chemical splash, a penetrating injury, or redness with severe headache, nausea or vomiting. Arrange a prompt examination if you wear contact lenses and have pain or discharge, or if redness is worsening or not settling. A clinician can inspect the cornea and measure eye pressure when needed.

Ask whether the redness is on the surface or deeper in the eye, whether you should pause contact lenses, and which drops are suitable. Mention when it began, one or both eyes, pain, discharge, light sensitivity, vision changes, injury, allergies and any medicines that affect bleeding.