You notice your child's eye is red and your inner mommy alarm goes off: Could it be pink eye? The next morning his eyelid is glued shut with gunk, and you know the diagnosis almost for certain.

Conjunctivitis, or pink eye, is practically a rite of passage for kids. Children miss 3 million school days annually in U.S. public schools because of it according to the American Journal of Infection Control.

Here are the telltale symptoms according to the Centers for Disease Control and Prevention (CDC) and American Academy of Ophthalmology (AAO):

  • Redness or swelling of the white of the eye or inside the eyelids
  • Increased tearing, mucus or pus production
  • Itchy, irritated and/or burning eyes
  • Increased sensitivity to light
  • Mild blurred vision due to mucus or pus
  • Gritty feeling in the eye
  • Crusting of the eyelids or lashes, especially in the morning

Conjunctivitis is caused by the swelling of the conjunctiva, a thin membrane that covers the inside of the eyelid and the white part of the eyeball, according to AAO. The "pink" in pink eye is the result of swollen blood vessels in the eye.

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Viral or bacterial?

Pink eye is usually caused by either a virus or bacteria. A third type, allergic conjunctivitis, is caused by allergic reactions — or by wearing your contacts too long. Allergic conjunctivitis can be treated with allergy medication.

Viral conjunctivitis is the most common. A number of different viruses can trigger it, including cold viruses and other viruses that cause upper respiratory infections and sore throat. Viral conjunctivitis spreads like wildfire and often results in epidemics. It's typically gone in one to two weeks, no treatment required. A warm compress can help with symptoms.

Bacterial pink eye usually causes a lot of pus, according to AAO. It can last as few as two to three days or as long as two or three weeks. It may resolve on its own, or the doctor may prescribe antibiotic eyedrops.

AAO recommends taking your child to see an ophthalmologist if symptoms persist or they worsen.

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If you suspect pink eye, let your child know to stop touching his eyes to avoid spreading it to other family members.

How to prevent pink eye

Good hygiene is the best way to prevent conjunctivitis. The AAO offers these tips:

  • Encourage kids to wash their hands often.
  • Avoid touching or scratching your eyes.
  • Stay away from anyone with pink eye.
  • Discourage the reusing of towels, washcloths, handkerchiefs and tissues to wipe the face and eyes.
  • Change your bed sheets and pillowcases frequently.
  • Don't use old cosmetics or share them with others.
  • Clean your contact lenses properly.

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Muriel Vega is a writer with a passion for budget travel and staying safe while abroad. A Georgia State University graduate, she has over 6 years of editorial experience and has written for The Guardian, The Atlantic, The Billfold, among other outlets. In her free time, you can find her baking pies, playing with her two dogs and cat, or planning her next vacation. She spends way too much time on Twitter, one of her favorite social media channels. Her favorite safety tip: Make sure you have all the necessary shots before you go abroad.