One Eye Always Red: What to Know

Redness occurs when small blood vessels on the eye surface widen or become irritated. Dryness, smoke, dust, rubbing, a minor surface injury and inflammation can all do this. Allergic conjunctivitis can present with redness and itching, while conjunctivitis may add discharge and eyelid crusting. Persistent one-sided redness may also reflect a problem beneath the surface, so its duration and associated symptoms matter. A photograph, examination and medication review can help distinguish surface irritation from a condition needing treatment.

Stop rubbing the eye and take a break from contact lenses and eye makeup. Rinse away obvious irritants with clean water, use a cool compress for irritation, and wash your hands regularly. Avoid using leftover antibiotic or steroid eye drops without advice; the wrong drop can hide symptoms or worsen some conditions. Note when the redness began, whether it fluctuates, and whether discharge or vision changes occur. Book an appointment if it continues despite these measures.

Seek urgent eye care for moderate or severe pain, new blurred vision, strong light sensitivity, a marked headache with nausea, an irregular pupil, injury, or a chemical exposure. Contact-lens wearers need prompt advice for a red eye, particularly with pain or reduced vision. Same-day assessment is also sensible when swelling is rapidly increasing or discharge is heavy. Do not drive if vision is impaired.

What part of the eye is causing the redness? Could allergy or conjunctivitis explain it? Do I need a pressure, corneal or vision check? Which drops should I avoid, and when should I return if it does not improve?