Pink Eye
Symptoms, Causes, Treatments, Questions & Related Topics

What is Pink Eye?

Pink eye is a condition that can usually be self-diagnosed – you simply know when you have it. When you wake up with red, itchy, mildly painful eyes that are excreting a discharge that cause your eyes to become crusty, you very likely have pink eye. Pink eye, also called conjunctivitis, is a very common condition with more than 3 million cases per year in just the U.S. alone. Its prevalence could be due to the fact that it’s highly contagious. Pink eye is spread by contact with eye secretions from someone who is infected, so it’s important to maintain good hygiene when you have it.

Top 5 Pink Eye Causes

1. Viruses

Pink eye can be caused by a number of viruses, particularly herpesvirus and adenovirus. When caused by a virus, pink eye tends to occur in both eyes and produce a clear, watery discharge.[1] Viral pink eye might accompany a sore throat, cold, or upper respiratory tract infection. Viruses that cause pink eye commonly spread through hand-to-eye contact by hands or objects contaminated with the virus.

Many times, pink eye caused by a viral infection produces mild symptoms and clears on its own within one to two weeks. More severe cases of viral pink eye take longer than two weeks to clear but can be treated with antiviral medications. You can prevent viral pink eye by avoiding contact with an infected person, washing your hands regularly, and cleaning surfaces an infected person has touched.[1]

2. Bacteria

Pink eye can be caused by bacteria, including Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus.[2] Pink eye caused by a bacterial infection tends to occur only in one eye and continuously discharge pus and mucus. In some cases, your doctor might test a sample of the discharge to determine which strain of bacteria caused the pink eye. Bacterial pink eye sometimes occurs alongside an ear infection.

Mild cases of pink eye caused by bacteria tend to clear on their own, but antibiotics can shorten the illness and prevent the eye condition from spreading to others.[1] Antibiotic eye drops or ointments can sometimes resolve bacterial pink eye within several days.

3. Irritants

Pink eye can be caused by irritants and chemicals that irritate and infect both the eye and inner eyelid. Common irritants known to trigger pink eye include smog, smoke, dirt, swimming pool chlorine, shampoo, cosmetics, contact lenses, and lens solution and cases.[3] Toxic chemicals in workplace environments can also cause this type of pink eye, also known as chemical conjunctivitis.

Pink eye caused by chemicals is not contagious; you can prevent it by avoiding contact with the irritant that triggered symptoms and by wearing eye goggles in environments that expose you to chemicals and other irritants.[2] Chemical conjunctivitis can be treated by rinsing the irritant from the eye and using eye drops or ointment to reduce irritation and redness. People who suffer additional symptoms of severe eye swelling, eye pain, and vision impairment should see a doctor for treatments that reduce or reverse symptoms.

4. Allergens

Pink eye caused by allergens is known as allergic conjunctivitis. People who are allergic to mold, pet dander, pollen, and dust mites can suffer pink eye symptoms when coming into contact with these substances or when the substances enter and irritate the eye and inner eye lining.[1] Allergic conjunctivitis always affects both eyes and produces watery discharge.

Allergic pink eye sometimes accompanies other allergy symptoms, including sneezing, itchy nose, and scratchy throat.[4] You can prevent symptoms caused by allergic conjunctivitis by avoiding contact with known allergens and environments that contain them. Eye drops and allergy medications can treat this condition.

5. Fungi, Amoeba, and Parasites

Fungi, amoeba, and parasites can enter and infect the eye, causing ocular diseases that include flashes and floaters, glaucoma, and pink eye.[5] Contact lenses stored in tap water or dirty lens solution can accumulate amoeba that live on the lens and transfer to the eyes. Pink eye caused by amoeba might accompany additional symptoms such as sensitivity to light and a feeling of something in the eye.

Pink eye can also be caused by parasites and amoeba that live in lakes, ponds, and other bodies of water, or that are carried by face flies and other insects. People who eat contaminated pork, chicken, or fish can be infected by parasites that cause symptoms such as pink eye.[5]

You can prevent ocular diseases caused by fungi, amoeba, and parasites by practicing good hygiene, including proper handling of contact lenses. Avoiding environments that expose you to harmful fungi, amoeba, and parasites can prevent pink eye; these environments include parts of the world where meats may be infected or contaminated and places where these organisms thrive, such as the Ohio and Mississippi River valleys and parts of West and South Africa.[5]

6 Possible Health Conditions Related to Pink Eye

1. Gonorrhea

Also known as the clap, this sexually transmitted infection can infect mucous membranes in the eyes to cause pink eye, swelling of the eye, and vision impairment.[6]

2. Chlamydia

This sexually transmitted infection can cause symptoms of pain on external sexual organs and discharge from the penis, vagina, and/or eyes.

3. Adenoviruses

This group of common viruses can cause a number of illnesses, including bronchitis, pneumonia, and pink eye.[7]

4. Measles

This viral infection of the respiratory system can cause watery eyes, redness, and other pink eye symptoms.[8]

5. Chickenpox

This viral infection, characterized by itchy, red rash and blisters, also produces symptoms of fever, fatigue, appetite loss, sore throat, and pink eye.[9]

6. Herpes

This virus can cause pink eye and another eye condition called keratitis, marked by symptoms of eye pain and redness, watery discharge, and blurred vision.[10]

Treatment of Pink Eye

In most cases, pink eye clears by itself within a couple of days or weeks, but if you feel that your pink eye is worsening, simply not getting any better, or you want to speed up the recovery process, see a doctor as they will be able to prescribe prescription eye drops or antibiotics and get you on the road to recovery.

Questions Your Doctor May Ask About Your Pink Eye

  • When did your pink eye symptoms begin?
  • Do you know what triggered your pink eye symptoms?
  • Does anything work to improve your symptoms?
  • Are there any factors that worsen your symptoms?
  • Are you experiencing pink eye in one or both eyes?
  • Do you wear contact lenses?
  • Have you recently started using new eye drops or contact lens solution?
  • How often do you clean your contact lenses?
  • How often do you replace the storage case for your contact lenses?
  • Does anyone else you know have pink eye right now?
  • What other symptoms do you experience aside from pink eye?
  • Have you recently spent time near a body of water or traveled overseas?

Pink Eye May Also Be Known as

  • Conjunctivitis
  • Viral conjunctivitis
  • Eye redness
  • Eye inflammation
  • Ophthalmitis


  1. National Eye Institute. Facts About Pink Eye.
  2. Centers for Disease Control and Prevention. Conjunctivitis (Pink Eye): Causes.
  3. Centers for Disease Control and Prevention. Pink Eye: Usually Mild and Easy to Treat.
  4. National Library of Medicine. Allergic conjunctivitis.
  5. National Library of Medicine. Fungal and Parasitic Infections of the Eye.
  6. National Library of Medicine. Gonorrhoea presenting as red eye: Rare case.
  7. Centers for Disease Control and Prevention. Adenoviruses.
  8. Centers for Disease Control and Prevention. Conjunctivitis (Pink Eye): For Clinicians.
  9. National Library of Medicine. Red eye in chickenpox: varicella-related acute anterior uveitis in a child.
  10. Centers for Disease Control and Prevention. Basics of HSV (Herpes Simplex Virus) Keratitis.

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