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Conjunctivitis is redness and inflammation of the thin layer of tissue that covers the front of the eye (conjunctiva). It is very common.
People often refer to conjunctivitis as red eye.
Other symptoms of conjunctivitis include itchiness and watering of the eyes, and sometimes a sticky coating on the eyelashes (if it's caused by an allergy). Read more about the symptoms of conjunctivitis.
Conjunctivitis can affect one or both eyes.
What causes conjunctivitis?
The conjunctiva can become inflamed as as result of:
- a bacterial or viral infection – this is known as infective conjunctivitis
- an allergic reaction to a substance such as pollen or dust mites – this is known as allergic conjunctivitis
- the eye coming into contact with substances that can irritate the conjunctiva, such as chlorinated water or shampoo, or a loose eyelash rubbing against the eye – this is known as irritant conjunctivitis
Read more about the causes of conjunctivitis.
Conjunctivitis often doesn't require treatment as the symptoms usually clear up within a couple of weeks. If treatment is thought necessary, the type of treatment will depend on the cause but in most cases antibiotic eye drops can be used to clear the infection.
Irritant conjunctivitis will clear up as soon as whatever is causing it is removed.
Allergic conjunctivitis can usually be treated with anti-allergy medications such as antihistamines. If possible, avoid the substance that triggered the allergy.
It's best not to wear contact lenses until the symptoms have cleared up. Any sticky or crusty coating on the eylids or lashes can be cleansed with cotton wool and water.
Infective conjunctivitis is easily spread, although it isn't necessary to stay away from work or keep your child away from school. Washing your hands regularly and avoiding sharing pillows or towels will help prevent it spreading.
Read more about treating conjunctivitis.
See your GP immediately if you have:
- eye pain
- sensitivity to light (photophobia)
- disturbed vision
- intense redness in one or both of your eyes
- a newborn baby with conjunctivitis
Conjunctivitis can be a frustrating condition – especially allergic conjunctivitis – but in most cases it doesn't pose a serious threat to health.
Complications of conjunctivitis are very rare but when they do occur they can be serious, such as:
- a severe case of allergic conjunctivitis can lead to scarring in the eye
- in cases of infective conjunctivitis the infection can spread to other areas of the body, triggering more serious secondary infections such as meningitis (an infection of the outer layer of the brain)
Read more about the complications of conjunctivitis.
- An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.
- Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and others are good for you.
- Immune system
- The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.
- Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.