The Facts

Conjunctivitis, also known as "pink eye," is a common eye condition. It's an inflammation of the conjunctiva, the membrane that covers the white of the eye and the inside of the eyelids. Within this membrane, there are tiny blood vessels that get enlarged when the conjunctiva become irritated. The enlarged blood vessels make the eye look red.


The most common causes of conjunctivitis are viruses and bacteria, but other causes include allergies, ultraviolet light, and chemical or environmental irritants.

Viral conjunctivitis is caused by the same viruses that are also often responsible for the common cold. Viral conjunctivitis is often accompanied by a common cold. These viruses are highly contagious (easily spread from person to person), and anyone can transfer the virus to his or her eye by blowing their nose with their eyes open or rubbing their eyes.

Bacterial conjunctivitis is caused by various types of bacteria. Bacterial conjunctivitis is also contagious and usually requires a short course of antibiotic eye drops or ointment.

Allergic conjunctivitis is not contagious and usually occurs in the spring, summer, and early fall. It is usually triggered by exposure to plant pollen and grasses. People who are allergic to animals or dust mites may be affected year-round.

Chemical or irritative conjunctivitis is also not contagious and is caused by exposure to irritants including:

  • chlorine from swimming pools
  • contact lens solutions
  • cosmetics
  • foreign objects
  • injury to the eye
  • intense light (i.e., snow blindness)
  • smoke
  • wind

Conjunctivitis may also occur in people with certain medical conditions. These include thyroid disease, gout, certain types of cancer, certain skin conditions such as rosacea or psoriasis, tuberculosis, and syphilis.

Symptoms and Complications

Signs and symptoms of conjunctivitis include:

  • burning, scratchy, or gritty feeling
  • pus-like discharge
  • redness
  • sensitivity to light
  • tearing

Serious complications of conjunctivitis are very rare.

Making the Diagnosis

If someone's eye is bloodshot and inflamed, they may have conjunctivitis. Conjunctivitis can have different symptoms depending on the cause. If a person has a cold and suddenly develops red eyes with little or no discomfort and clear eye discharge, it may be viral conjunctivitis. Bacterial conjunctivitis causes some eyelid swelling and thick, yellow or green eye discharge. If the eyes get red and itchy at the onset of pollen season, it is probably due to allergic conjunctivitis.

A doctor or health care professional should be consulted if:

  • there is pain, altered vision, severe redness, or unusual sensitivity to light
  • self-treatment for more than 2 to 3 days does not clear the irritation
  • the irritation worsens or has been present for more than 2 days
  • the condition recurs
  • you have an underlying condition, such as diabetes
  • it is a child who has conjunctivitis

Treatment and Prevention

Treatment of conjunctivitis depends on the original cause. Applying cool compresses 3 to 4 times a day and using eye drops such as artificial tears can help viral conjunctivitis. Anyone with suspected viral conjunctivitis should see their doctor.

Artificial tears or antihistamine eye drops can relieve allergic conjunctivitis. Antihistamine eye drops include olopatadine and ketotifen*. Eye drops containing mast cell stabilizers (medications, which prevent the release of histamine, e.g., cromolyn, lodoxamide) have also been found effective in preventing and treating allergic conjunctivitis.

Steroid eye drops such as dexamethasone, prednisolone, or fluorometholone can be used sparingly for extreme allergic reactions. Antihistamines taken by mouth may be useful in the treatment of allergic conjunctivitis, especially when other areas of the body are also affected by the allergies. Ask your pharmacist or doctor for appropriate recommendations.

If bacteria are the cause of conjunctivitis, antibiotic eye drops or ointments are usually prescribed. Non-prescription products can include a combination of polymyxin B, bacitracin, and gramicidin as eye drops or eye ointment. Talk to your pharmacist before using these medications and make sure you consult your doctor if the condition worsens or does not improve within 2 days.

Many prescription products are available for treatment of bacterial conjunctivitis. Example of prescription antibiotic eye drops or ointments that may be used to treat bacterial conjunctivitis include erythromycin, ciprofloxacin, gatifloxacin, fusidic acid, moxifloxacin, and ofloxacin.

People who are around someone with infectious conjunctivitis should avoid touching the person's face, hands, or any items they have handled. They should wash their hands frequently and avoid sharing towels, pillowcases, face cloths, or soap with anyone who is infected. People with conjunctivitis should wash their hands, towels, face cloths, and pillowcases frequently; this may help prevent the spread of the conjunctivitis to the other eye and may help clear it up faster. For people who use eye makeup, they should throw it out and buy a fresh supply – makeup is likely to cause a reinfection.

Children should be taught to blow their noses carefully and to cover their nose and mouth when coughing or sneezing. Some children have a habit of wiping their nose with an upward motion of the palm. Try to discourage this.

Conjunctivitis caused by allergens or irritants isn't contagious but it's difficult to avoid. People can't anticipate everything that might bother their eyes. The best solution is to steer clear of obvious irritants; for example, stop wearing contact lenses until symptoms are resolved, wear goggles when swimming, and avoid smoke-filled rooms. The best way to prevent allergic conjunctivitis is to avoid the offending allergens. Keep windows closed over the warmer months to keep out pollens and moulds.

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