Conjunctivitis

Conjunctivitis, commonly known as pink eye, is one of the most frequent eye conditions people experience. This inflammation of the clear membrane covering the eye can make your eyes appear pink or red, often with discharge and discomfort, but it rarely threatens your vision.

Pink eye

Table of contents

• What is conjunctivitis
• Symptoms of conjunctivitis
• Causes and types of conjunctivitis
• How conjunctivitis is diagnosed
• Treatment options
• Prevention and hygiene
• When to see a healthcare provider

What is conjunctivitis

Conjunctivitis is an inflammation of the conjunctiva, the thin, transparent membrane that covers the white part of your eye and lines the inside of your eyelid^[1]. When small blood vessels in the conjunctiva become swollen and irritated, they become more visible, which is what causes the whites of the eyes to appear reddish or pink^[1].

• Conjunctiva (eye membrane)
• Eyelid
• Sclera (white of the eye)

Pink eye is extremely common and can affect one eye or both eyes at the same time^[2]. The condition can be short-term, lasting fewer than four weeks (acute conjunctivitis), or long-term, lasting more than four weeks (chronic conjunctivitis)^[2]. Though pink eye can be irritating, it rarely affects your vision^[1].

Symptoms of conjunctivitis

The most common symptoms of conjunctivitis include redness in one or both eyes, which is often the first sign people notice^[1]. You may experience itchiness in one or both eyes and a gritty feeling, as though something is stuck in your eye^[1][2].

Discharge is another hallmark symptom. This discharge can be thick and may be yellow, green, or white in color^[2]. It often forms a crust on your eyelashes or eyelids during the night, which may prevent your eye or eyes from opening in the morning^[1]. Your eyes may also be watery or feel dry and irritated^[2].

Other symptoms include burning eyes, blurred vision that may come and go, sensitivity to light (called photophobia), and swollen eyelids^[1][2]. Eye pain is usually mild if present at all^[2]. When pink eye is caused by allergies, itching is the most consistent sign^[5].

Causes and types of conjunctivitis

Healthcare providers usually divide conjunctivitis into two main categories: infectious and noninfectious^[2].

Infectious conjunctivitis

Viral conjunctivitis is the most common overall cause of infectious conjunctivitis^[4]. It is most often caused by infections from the adenovirus family, but can also be caused by other viruses including measles, mumps, COVID-19, eye herpes, and hand, foot and mouth disease^[2]. Viral pink eye is highly contagious and can spread through direct contact with eye discharge, contaminated surfaces, or respiratory droplets^[11]. It usually does not require treatment and most cases are mild, clearing up in 7 to 14 days^[10].

Bacterial conjunctivitis is the second most common cause of infectious conjunctivitis^[2][4]. The bacteria that cause staph infections, strep throat, and some types of meningitis can all cause bacterial conjunctivitis^[2]. Sexually transmitted infections like chlamydia, gonorrhea, and syphilis can also lead to pink eye^[2]. Bacterial pink eye often produces a thick, sticky discharge and is very contagious^[11]. Most uncomplicated cases resolve in 1 to 2 weeks^[4].

Fungal and parasitic infections can also cause pink eye, but this is much less common than viral or bacterial infections^[2].

Noninfectious conjunctivitis

Allergic conjunctivitis occurs when allergens such as molds, pollen, or animal dander irritate your conjunctiva^[2]. This type is encountered in up to 40% of the population, though only a small proportion of these individuals seek medical help^[13]. Unlike viral or bacterial pink eye, allergic conjunctivitis is not contagious and often occurs seasonally^[5][11].

Irritants such as smoke, pool chlorine, air pollution, chemicals, soap, cosmetics, or dirt can also cause conjunctivitis^[2]. Your contact lenses or contact solution can sometimes irritate your eyes, even if they usually don’t^[2]. Some medications can cause pink eye as a side effect^[2].

Eye injuries that damage your conjunctiva can lead to conjunctivitis, as can certain autoimmune diseases^[2]. In much rarer cases, tumors or eye cancers can cause symptoms^[2].

How conjunctivitis is diagnosed

In most cases, your healthcare professional can diagnose pink eye by asking about your recent health history and symptoms and examining your eyes^[8]. Healthcare providers can usually identify pink eye by examining the eye while considering patient history and other symptoms^[10].

Rarely, your care professional may take a sample of the liquid that drains from your eye for laboratory analysis, called a culture^[8]. A culture may be needed if your symptoms are severe or if your care professional suspects a high-risk cause, such as a foreign body in your eye, a serious bacterial infection, or a sexually transmitted infection^[8]. Sometimes, healthcare providers might collect a sample from the patient’s eye and send it to a laboratory to identify the type of pink eye^[10].

Treatment options

Pink eye is treatable, and some types can be managed at home without medical treatment^[3]. Treatment depends on the underlying cause of the conjunctivitis^[1].

Home care and symptom relief

Pink eye treatment is usually focused on symptom relief^[8]. Your care professional may recommend using artificial tears, cleaning your eyelids with a wet cloth, and applying cold or warm compresses several times daily^[8]. You can purchase cold compresses and artificial tears over the counter without a prescription to help relieve some of the inflammation and dryness caused by pink eye^[10].

If you wear contact lenses, you’ll be advised to stop wearing them until treatment is complete^[8]. Your care professional will likely recommend that you throw out soft contacts you’ve already worn and disinfect hard lenses overnight before you reuse them^[8]. You should also replace any eye makeup used before your illness^[8].

Treatment for viral conjunctivitis

In most cases, you won’t need antibiotic eye drops for viral conjunctivitis. Since conjunctivitis is usually viral, antibiotics won’t help^[8]. Antibiotics will not improve viral pink eye because these drugs are not effective against viruses^[10]. Instead, the virus needs time to run its course, which typically takes around 2 to 3 weeks^[8].

Most cases of viral pink eye are mild and usually clear up in 7 to 14 days without treatment and without any long-term consequences^[10]. However, antiviral medicines may be an option if your viral conjunctivitis is caused by the herpes simplex virus or varicella-zoster virus^[8][10].

Treatment for bacterial conjunctivitis

Mild bacterial pink eye may get better without antibiotic treatment and without causing any complications^[10]. It usually clears up in 2 to 5 days without treatment but can take 2 weeks to go away completely^[10]. The majority of cases in bacterial conjunctivitis are self-limiting and no treatment is necessary in uncomplicated cases^[13].

However, topical antibiotics decrease the duration of bacterial conjunctivitis and allow earlier return to school or work^[13]. Your doctor may prescribe an antibiotic, usually given topically as eye drops or ointment, for bacterial pink eye^[10]. Antibiotics may help shorten the length of infection, reduce complications, and prevent the spread to others^[10].

Conjunctivitis caused by gonorrhea or chlamydia and conjunctivitis in contact lens wearers should be treated with antibiotics^[13]. Conjunctivitis secondary to sexually transmitted diseases requires systemic treatment in addition to topical antibiotic therapy^[13].

Treatment for allergic conjunctivitis

Pink eye caused by an allergen usually improves by removing the allergen from the person’s environment^[10]. Treatment consists of topical antihistamines and mast cell inhibitors^[13]. Allergy medications and certain eye drops, including some prescription eye drops, can provide relief from allergic conjunctivitis^[10]. In some cases, your doctor may recommend a combination of drugs to improve symptoms^[10].

Prevention and hygiene

Viral and bacterial pink eye can spread easily from person to person^[16]. Pink eye caused by an infection can easily spread, and you can accidentally pass it to other people or spread it from one eye to the other^[2].

Washing your hands often is the best way to prevent pink eye and stop it from spreading^[7]. Wash your hands with soap and water for at least 20 seconds, especially before and after cleaning or applying eye drops or ointment to your infected eye^[16]. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol^[16].

Avoid touching or rubbing your eyes with your fingers^[16]. Do not share personal items like pillows, washcloths, towels, eye drops, eye or face makeup, makeup brushes, contact lenses, contact lens cases, or eyeglasses^[16].

Wash pillowcases, sheets, washcloths, and towels often in hot water and detergent^[16]. If you have conjunctivitis, you should also avoid using swimming pools^[16].

If you wear contact lenses, always wash your hands before putting in or taking out your lenses^[7]. Regularly clean and replace your contact lenses as recommended, and never swim in lakes or hot tubs while wearing contact lenses^[7].

When to see a healthcare provider

There are serious eye conditions that can cause eye redness^[1]. You should see a healthcare provider if you have pink eye along with any of the following symptoms^[10]:

• Eye pain
• Light sensitivity
• Blurred vision that does not improve when discharge is wiped from the eyes
• Intense eye redness
• Symptoms that get worse or do not improve
• Bacterial pink eye which does not improve after 24 hours of antibiotic use
• A weakened immune system

Newborns with symptoms of pink eye should see a doctor right away^[10]. Ophthalmia neonatorum is a severe form of bacterial conjunctivitis that occurs in newborn babies and is a serious condition that could lead to permanent eye damage if it is not treated immediately^[5].