Conjunctivitis (Pink Eye)

What causes conjunctivitis

Viral conjunctivitis

The most common type, usually caused by adenovirus, often with a cold or sore throat. It typically starts in one eye and spreads to the other within days. Discharge is watery; eyes feel gritty or burning; the lymph node in front of the ear may be tender. It is very contagious and can last 1 to 3 weeks, sometimes with blurred vision from small spots on the cornea. See viral conjunctivitis.

Bacterial conjunctivitis

Caused by bacteria such as Staphylococcus, Streptococcus pneumoniae and Haemophilus influenzae, more common in children. It produces thick yellow or green discharge that glues the lids together in the morning. It is contagious. In sexually active adults, gonorrhea and chlamydia can cause severe or persistent conjunctivitis. See bacterial conjunctivitis.

Allergic conjunctivitis

Caused by pollen, dust mites, pet dander or mold. Both eyes are intensely itchy, watery and red, with puffy lids and often sneezing and a runny nose. It is not contagious. See allergic conjunctivitis.

Irritant and other causes

Smoke, chlorine, chemicals, foreign bodies, contact lens overuse and dry eye can all cause red, irritated eyes.

Viral vs bacterial vs allergic: how to tell

White discharge from the eye

Stringy, white mucus is typical of allergic conjunctivitis and can also occur with dry eye and early viral infections. Thick white or yellow pus suggests bacterial infection. See white discharge from the eye.

Symptoms

• pink or red color in the white of one or both eyes
• gritty, burning or itchy feeling
• watering
• discharge, with crusting of the lashes, especially in the morning
• swollen eyelids
• mild sensitivity to light

Vision should be normal or only briefly blurred by discharge. Significant pain, persistent blurred vision or a strongly light-sensitive eye suggest keratitis, uveitis or acute glaucoma rather than simple pink eye.

Conditions that mimic pink eye

• Keratitis: infection or inflammation of the cornea, often from contact lenses; painful with blurred vision.
• Uveitis: inflammation inside the eye; aching pain, light sensitivity, redness around the cornea.
• Acute angle-closure glaucoma: severe pain, halos, headache, vomiting.
• Subconjunctival hemorrhage: a painless bright red patch from a burst vessel.
• Episcleritis and scleritis: redness in a sector of the eye; scleritis is very painful.
• Blepharitis: inflamed eyelid margins with crusting.

Diagnosis

Most conjunctivitis is diagnosed from symptoms and a simple eye examination. A clinician checks vision, looks at the eye with a light or slit lamp, and may use fluorescein dye to look for corneal damage. Swabs for testing are taken for severe, persistent or newborn cases, or when gonorrhea, chlamydia or herpes are suspected. A rapid adenovirus test is available in some clinics.

Treatment

Home care for all types

• Cool or warm compresses several times a day.
• Preservative-free artificial tears to soothe and rinse the eye.
• Clean discharge from the lids with a clean, damp cloth from the inside corner outward, using a fresh cloth for each eye.
• Stop wearing contact lenses until the eye is completely better, and replace the lens case and disposable lenses.
• Avoid eye makeup and discard makeup used while infected.

Viral

No antibiotics needed; they do not help. Symptoms often get worse for 3 to 5 days before improving. Herpes conjunctivitis needs antiviral treatment from a doctor.

Bacterial

Mild cases often clear on their own within a week. Antibiotic eye drops or ointment shorten the illness and allow earlier return to child care or school. Gonorrhea or chlamydia conjunctivitis needs oral or injected antibiotics.

Allergic

Avoid triggers, use cool compresses and artificial tears to rinse allergens, and use antihistamine or mast cell stabilizer eye drops; follow the label dose. Oral antihistamines help if nasal symptoms are present. Steroid eye drops are used only under an eye doctor's supervision.

How long pink eye is contagious

• Viral: contagious while the eye is red and discharging, often 10 to 14 days.
• Bacterial: contagious until about 24 hours after starting antibiotics, or until discharge stops.
• Allergic: not contagious.

Many schools allow children to return once symptoms are improving or after 24 hours of antibiotic treatment for bacterial pink eye; policies vary.

Prevention

• Wash hands often, and avoid touching or rubbing your eyes.
• Do not share towels, pillowcases, washcloths, eye drops or makeup.
• Clean contact lenses properly and never sleep in lenses unless approved.
• Wear swim goggles in chlorinated water.
• Treat allergies before the season starts if you are prone to allergic conjunctivitis.

Frequently asked questions

How can I tell if pink eye is viral or bacterial?

Viral pink eye usually causes watery discharge, a gritty feeling, and often comes with a cold. Bacterial pink eye causes thick yellow or green discharge that crusts the lids shut. The distinction is not always clear, and a clinician can help decide if antibiotic drops are needed.

What does white discharge with conjunctivitis mean?

Stringy white mucus is most typical of allergic conjunctivitis, especially with strong itching in both eyes. It can also occur with dry eye or viral infection. Thick, creamy white or yellow pus points more toward bacterial infection.

How long does pink eye last?

Viral pink eye lasts 1 to 2 weeks, sometimes up to 3. Bacterial pink eye usually improves within 2 to 5 days of antibiotic drops and clears within 1 to 2 weeks. Allergic conjunctivitis lasts as long as you are exposed to the allergen.

Do I need antibiotics for pink eye?

Usually not. Most pink eye is viral, and antibiotics do not help viruses. Antibiotic drops are used for bacterial conjunctivitis, especially with heavy discharge, contact lens use or when needed for school or child care return. Severe or newborn cases always need medical care.

When should I see a doctor for pink eye?

See a doctor for eye pain, light sensitivity, blurred vision, heavy discharge, symptoms in a newborn, a contact lens wearer with a red eye, a weakened immune system, or symptoms that do not improve within a week.