Conjunctivitis

At a glance

  • The protective membrane that covers the white part of the eye (conjunctiva) can become inflamed due to viruses, bacteria or an allergy.
  • This causes your eye to turn red and watery. Your eyelids may stick together, especially in the morning.
  • Conjunctivitis caused by viruses or bacteria usually goes away on its own, but it is contagious.
  • It's important not to touch your eyes with your fingers or objects such as eye droppers.
  • Antibiotic eye drops are only effective against bacterial infections.

Introduction

Photo of a man rubbing his eye
PantherMedia / twelvetribes

Conjunctivitis, also known as pink eye, is an of the conjunctiva. This is a protective membrane that covers the visible white part of the eye and the inner side of the eyelid. Conjunctivitis makes the affected eye(s) turn red.

The inflammation is commonly caused by germs such as viruses or (infectious conjunctivitis). But it is also often caused by an (allergic conjunctivitis).

It often affects both eyes because the can easily spread from one eye to the other. To prevent this from happening, it's important to avoid touching an infected eye. If you do touch it, be sure to wash your hands right away. It is also a good idea to use your own towels and washcloths, and not share them with other people.

Illustration: Side view of the eye showing the conjunctiva (in red) – as described in the article

Side view of the eye showing the conjunctiva (in red)

Symptoms

Bacterial conjunctivitis makes your eyes red and watery. The conjunctiva produces a yellowish-white discharge that makes your eyelids stick together. This is especially noticeable when you wake up in the morning. The conjunctiva can also become sore and hurt when you move your eye, and you may have an itching and burning sensation in your eyes.

Viral conjunctivitis has similar symptoms, but the eyes typically secrete a more watery fluid.

If conjunctivitis is caused by an , both eyes are always affected. Here, too, the eyes water. Itching is a typical sign of an allergy. Allergic conjunctivitis is often accompanied by other symptoms such as a runny nose.

Poor vision, increased sensitivity to light, the feeling that you have something in your eye, or a severe headache together with nausea are rare, but may be signs of a more serious problem. It is important to see a doctor if you have any of these symptoms.

Illustration: Inflamed conjunctiva – as described in the article

Inflamed conjunctiva

Causes

Conjunctivitis is often caused by viruses or bacteria. Viral and bacterial conjunctivitis are both contagious. The germs are often transferred by touch, and the can spread from one eye to the other – for instance, if you touch both eyes with your fingers. But it can also spread through contact with objects such as eye drop bottles, tissues, washcloths or binoculars.

Another common cause of conjunctivitis is allergic reactions – for instance, to pollen, animal fur or dust mites. Conjunctivitis can also be caused by dust or dirt, dry air, irritating liquids or damage to the conjunctiva. Sometimes the eye isn't kept moist enough with tear fluid, and that can lead to conjunctivitis too. If conjunctivitis is caused by an or another external factor, it is not contagious.

Outlook

Bacterial conjunctivitis usually doesn't have any serious consequences. In more than half of all people, it goes away without treatment within one to two weeks. Viral conjunctivitis often goes away on its own within a few weeks too.

Conjunctivitis can also become chronic. It is considered to be chronic if it lasts longer than four weeks.

Effects

In rare cases the can spread to the (the transparent front surface of the eye). This is more likely to happen if you wear contact lenses. But the risk of keratitis ( of the ) is very small: Only about 3 out of 10,000 people who wear contact lenses develop keratitis after having conjunctivitis.

Diagnosis

If the doctor thinks you may have conjunctivitis, they will ask you about the typical symptoms (such as itching, the feeling that you have a foreign object in your eye, or sticky eyelids) and how long you have had these symptoms for. After that, your eyes and eyelids will be examined to find or rule out any possible injuries or external irritants.

It usually isn't possible to say whether conjunctivitis is bacterial or viral based on the symptoms alone. In rare cases, a sample of the eye discharge is taken to find out what type of germs the is being caused by.

Treatment

Although conjunctivitis is more commonly caused by viruses than , doctors often prescribe antibiotic eye drops or creams "just in case." But antibiotics are only effective against bacteria, and have no effect on viruses. If the is viral, only the symptoms can be treated.

Some people try out non-antibiotic eye drops. Cold or lukewarm compresses are also common. The effects of these treatments have not been properly studied, though. It is not clear if they are helpful, useless or possibly even harmful.

If conjunctivitis is caused by an , it can be treated with medicines such as antihistamines or mast cell stabilizers. These are used in the form of eye drops.

People who usually wear contact lenses are advised to wear glasses instead when they have conjunctivitis. Previously worn contact lenses should be cleaned particularly thoroughly if you want to use them again after the has cleared up. The same is true for contact lens cases. This can prevent you from getting conjunctivitis again.

Azari AA, Arabi A. Conjunctivitis: A Systematic Review. J Ophthalmic Vis Res 2020; 15(3): 372-395.

Berufsverband der Augenärzte Deutschlands (BVA), Deutsche Ophthalmologische Gesellschaft (DOG). Leitlinie Nr. 12: Bakterielle Konjunktivitis. 2011.

Castillo M, Scott NW, Mustafa MZ et al. Topical antihistamines and mast cell stabilisers for treating seasonal and perennial allergic conjunctivitis. 2015; (6): CD009566.

Epling J. Bacterial conjunctivitis. BMJ Clin Evid 2012: pii: 0704.

Sheikh A, Hurwitz B, van Schayck CP et al. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev 2012; (9): CD001211.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on December 8, 2021
Next planned update: 2024

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Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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