Whether you look like you pulled the world's longest all-nighter or feel so itchy you want to claw your eyeballs out, you shouldn't just slap on a pair of sunglasses and ignore it. Treating eye issues properly can help you avoid complications, says Stephanie J. Marioneaux, MD, spokesperson for the American Academy of Ophthalmology with a clinical practice in Chesapeake, Va. "Especially if you have pain, a change in vision, discharge, light sensitivity or any symptoms that persist, it could be a sign of a serious problem, and you should see an ophthalmologist," she says. Decode your eye problem with this guide.

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Your symptoms:
Red eyes
Both eyes are itchy and watery

It's probably allergies, aka allergic conjunctivitis—a reaction to pollen, pet dander, or something else in your environment. Get away from the trigger if possible, whether it's a fluffy cat, a dusty attic or a park full of ragweed. Then take an oral antihistamine to halt the immune system reaction, says Tim Mainardi, MD, an allergist with New York-Presbyterian/Weill Cornell Medicine in New York City. Over-the-counter allergy drops may calm inflammation and soothe itchiness directly. You can also ask your eye doc about prescription drops. Skip anti-redness drops; they don't treat the root cause and can lead to rebound redness. If allergies are a seasonal nuisance for you or create major discomfort, see an allergist for additional treatment.

Your symptoms:
Red eyes
Discharge that's thick and crusty (along with itching)

You might have conjunctivitis—inflammation from an infection of the outer layer of your eye. Your primary care doc can do a culture to see if it's viral or bacterial. The viral variety is "like a common cold in the eye" and is extremely contagious, says Dr. Marioneaux. Individual vials of artificial tears and cold packs will help relieve irritation and swelling. A mild case of bacterial conjunctivitis may go away on its own, but your doctor may also prescribe antibiotic eye drops to speed things up. Dial an ophthalmologist if fluids are draining from your eye or if you have moderate to severe pain, light sensitivity, blurred vision or intense redness.

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Your symptoms:
A painful lump at the edge of one eye or under your eyelid

If it's at the edge of your lid, that pimple-like bump might be a sty. Sties are caused by an infected eyelash follicle; they can get tender and swollen and may ooze pus. Use a warm washcloth to encourage drainage; if it's really bothersome or painful, or if it doesn't improve with home treatment, see your eye doctor, who can prescribe an antibiotic ointment. A chalazion results from a clogged oil gland under the eyelid, farther from the lashes. "You can feel the bump sticking out through the lid," says Dr. Marioneaux. Warm compresses are also the first line of treatment here. If a sty or chalazion hardens and persists, an ophthalmologist can drain it or inject it with a steroid to bring down swelling.

Your symptoms:
Red eyes
A gritty, sandy feeling

It could be dry eye, a condition in which the eyes aren't getting enough moisture because you're not making enough tears, your tears aren't watery enough and/or they're evaporating too quickly, which can happen when oil-producing glands in your eyelids are inflamed. Staring at screens without blinking regularly is a culprit. "If you're not blinking every four seconds, oil doesn't get released and tears evaporate, leaving the eye dry and irritated," says Dr. Marioneaux. "If your eyes water out of nowhere, that's emergency tears coming to the rescue." Dry eye can also be a side effect of some medications or the result of hormonal fluctuations or long-term use of contact lenses. Steer clear of air-conditioning or forced-air heat, which may hasten tear evaporation; take breaks from intense staring, and dampen eyes with artificial tears. You can also try adding more omega-3 fatty acids to your diet (good sources are fatty fish, like salmon) and using a humidifier to moisten the air. More severe cases may require a prescription ointment, Rx eye drops or plugs placed in the eye's drainage ducts to hold tears in your eyes longer. Don't ignore dry eye, because it could lead to scarring of the cornea and vision loss.

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Your symptoms:
Red eyes
A gritty, sandy feeling
Eye is red and/or irritated along the lash line specifically

It might be blepharitis, a chronic condition in which oil glands along the lash line become clogged. Treat it daily for best results. "Warm compresses increase blood flow and loosen the oil to help unclog the glands," says Payal Patel, MD, a clinical instructor in the department of ophthalmology at NYU Langone Medical Center, who recommends applying a warm washcloth to the eyelid for one to two minutes three or four times a day. You can also clean the eyelids by gently massaging the lash line with tear-free shampoo on a clean fingertip, washcloth or Q-tip. Use artificial tears to ease irritation or burning during the day.

Your symptoms:
Red eyes
Persistent blurred vision or a sharp pain after a blow to the eye or getting a foreign object stuck in your eye

You could have a scratched cornea (the layer covering the front of your eye). See your eye doctor ASAP or go to an ER or urgent care center anytime you suspect a corneal abrasion.

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Your symptoms:
Red eyes
They're not itchy/watery, you don't have any discharge or a gritty feeling, there's no painful lump at the edge of one eye and you do not have persistent blurred vision or a sharp pain after a blow to the eye

Any eye symptoms that don't clear up warrant a call to your ophthalmologist.