Q: What causes bloodshot eyes, and should...

Q: What causes bloodshot eyes, and should I worry about them?

A: According to the UC Berkeley Wellness Letter, “bloodshot” refers to a relatively harmless condition in which small vessels on the surface of the eyeball are dilated and visible. Lack of sleep, alcohol consumption the night before, an allergy or overuse of contact lenses are possible causes of redness on awakening. During the day, the condition can be caused by irritants, eyestrain, rubbing the eyes excessively or anything that dries the eyes out.

Usually, bloodshot eyes improve by themselves. Washing with cold water can help, as can cold compresses. Eyedrops and eye washes can help, but overuse can actually increase redness. Very red, irritated eyes accompanied by itching and a discharge, however, are usually a sign of an infection and require treatment by a physician.