context: Ever look in the mirror and see two red eyes staring back at you? It happens to a lot of people every now and then. Your eyes get red when the tiny blood vessels on the surface of the eyes expand and turn the whites of one or both eyes a pink or reddish tint. Many things can cause it, like a night of heavy drinking, or a physical injury to your eye. But if you haven't had too much alcohol, or scratched or poked your eyeball recently, there are other possibilities. Allergy triggers may make your eyes red. Outdoor causes include pollen from grasses and trees. Indoor triggers include pet dander, dust or mold, or irritants like perfume and smoke. In these cases, your eyes may also have: Itching Burning Tearing You may also have nasal allergy symptoms, such as sneezing and a stuffy nose. Sometimes, the tears your eyes make are not the right consistency and evaporate too fast. And sometimes the eye can't make tears at all. This condition is called dry eye. It can cause pain, ulcers on your cornea or even, in rare instances, some vision loss. Besides eye redness, you may have some other symptoms of dry eye: A gritty feeling A burning sensation in the eye Occasional blurred vision Heavy eyelids Inability to cry Eye fatigue When your eyes aren't dry, you get a lot of tears A stringy discharge Discomfort with contact lenses Also known as conjunctivitis, pinkeye is when the lining inside your eyelid and the white of your eye become inflamed. Causes can include a virus, bacteria, an allergy, or irritants like swimming pool chlorine. It's very common, especially among children, and is very contagious. Other symptoms include: More tears than usual Your eyes burn, itch, or feel gritty White, yellow, or green discharge from your eyes Your eyes are more sensitive to light You get a crust on your eyelid or eyelashes This happens when tiny blood vessels break beneath the surface of your eye. The blood is trapped and makes the white of your eye look bright red. It can be caused by an intense sneeze, heavy lifting, hard vomiting, or even rubbing your eye a little too hard. Usually, the eye does not hurt. Broken blood vessels cause other symptoms like: A bright red area on your eye along with the general redness A scratchy sensation Sometimes fluid builds up in the front part of the eye. This causes pressure on the eye and can damage the optic nerve. This is called glaucoma, and is the leading cause of blindness for people 60 and over. The usual form of glaucoma is generally painless. An unusual form of acute glaucoma can cause symptoms such as: Severe pain in the eye Headache Decreased or blurred vision Rainbows or halos in your vision Nausea and vomiting It's usually nothing to worry about, as long as it only happens every now and then and doesn't last long. You might find temporary relief in over-the-counter eye drops, such as tear substitutes that wash and moisten the eye. But remember, routine and repeated use of these âget the red outâ drops will make the problem worse with your eyes becoming dependent on the drops and becoming even more red when the drops wear off. In that case, you could try a different brand or stop using them completely. Decongestants can help the itchiness along with the redness of allergies. You should call a doctor if, along with red eyes, you also have: A sudden change in vision Sensitivity to light Sudden halos around lights Severe headache, pain in the eye, or fever Nausea or vomiting A foreign object or substance in your eye Swelling in the eye Inability to keep the eye open