What causes red eyes?
Most of us have experienced bloodshot or red eyes. They can look unpleasant, with pink or red streaks in the conjunctiva and sclera, which are usually white. Bloodshot eyes can also be uncomfortable—with itchiness, tearing, and burning all common symptoms. Red eyes are usually caused by an external irritant (called an allergen), like:
- pollen (hay fever)
- chlorine from swimming pools
- cigarette smoke
To fight off the irritant, your eyes make a substance called histamine, which dilates and inflames the tiny blood vessels under the eye’s surface.
Many cases of red eye are harmless and respond well to home or over-the-counter treatments. The best thing you can do is find what allergen is causing the red eye, and avoid it. But some causes of red eye require medical diagnosis and prescription medication.
So, if you eye is red or bloodshot, what should you do? What can you do at home, and when should you see a doctor?
Brenda Pagán-Duran, MD, an ophthalmologist in New Jersey, has a few tips to help you decide.
You should see a doctor if your eyes are red and ...
- seeping or encrusted with yellow, brown or green mucous. This can be a sign of infection that needs urgent medical treatment.
- you are experiencing pain in or around your eyes or unusual tenderness.
- you have unusual sensitivity to light.
- you have a fever or overall sickness.
- redness or discomfort lasts more than a week, after you’re tried home remedies.
- your child has been exposed to pink eye (conjunctivitis) at school or at camp.
If you have bloodshot eyes, but none of these more serious symptoms, you can try a few things at home to help.
Home remedies for bloodshot eyes
- Using over-the-counter artificial tears. These drops relieve irritation and wash allergens from the eye. Use these up to four times per day. If you use artificial tears more often, you should get preservative-free artificial tears.
- Using over-the-counter antihistamine eye drops, especially if you are prone to seasonal allergies. These drops help relieve itchiness.
- Decongestants. These eye drops reduce the redness in your eyes. Avoid using these drops for more than three days. Long-term use can make redness worse (called “rebound redness”).
- Placing cool compresses or washcloths on your closed eyes a couple of times a day
- Avoiding triggers or irritants such as smoke, fumes, pollen, dust, chlorine or pet dander. If you don’t know what’s irritating your eye, see an allergist. They can test you to find out what you are allergic to.
- Dehumidify. If mold causes your red eyes, clean the mold in your home and consider a dehumidifier to absorb excess moisture.
- Washing your hands often, not touching your eyes unless you’ve just washed your hands, and using clean bedding and towels daily.
If home remedies don’t help after about a week, you could have an eye infection. Two main kinds of infection cause red eyes — viral and bacterial. There are also fungal eye infections, which are less common.
Pink eye (conjunctivitis) can be viral or bacterial. It’s important to get a diagnosis from a doctor, because treatments differ based on the kind of infection.
“I understand some people feeling this is just allergies or a virus and if I wait this will go away. But if you get other associated symptoms and it’s been a week, you want to make sure other things aren’t going on,” Dr. Pagán-Duran said.
Viral eye infections, the most common kind, tend to improve on their own, and don’t require prescription medication. Bacterial eye infections require antibiotics. Both types of infection are contagious and spread easily.
Family physicians or pediatricians can diagnosis most eye infections. Ophthalmologists have the tools and expertise for a more-detailed evaluation.