Patient information from BMJ

Conjunctivitis

Last published:Feb 09, 2024

If your eyes look red and feel gritty, you might have conjunctivitis. If your eyes don't start to feel better after a day or two you should see your doctor, pharmacist, or optician. This is because red, sore eyes can occasionally mean a more serious problem.

What is conjunctivitis?

Conjunctivitis happens when the lining of your eye is irritated. This lining is called conjunctiva. It is a thin lining that covers the inside of your eyelids and your eyeballs.

Conjunctivitis can be caused by bacteria or viruses. Or it can be an allergic reaction to things such as dust, sand, and pollen. It can also sometimes be caused by other things, such as certain chemicals, and problems with contact lenses.

Viral and bacterial conjunctivitis spread easily from person to person. They are common among school children. Adults are more likely to get conjunctivitis if they have very dry eyes.

Conjunctivitis usually clears up on its own after a few days.

What are the symptoms?

Symptoms of conjunctivitis include watery, red, or sore eyes. Your eyes may feel gritty and irritated, stinging, or burning. If you also have white or yellow pus coming from your eyes, which causes crusts on your eyelids while you sleep, you probably have a bacterial infection.

Your eyes may also itch. This could be a sign of an allergic infection. If you get several attacks in a short space of time, your symptoms might be caused by an allergy. It could also be caused by re-infection (an infection that is cured and then comes back). If you get conjunctivitis symptoms every year at the same time, it's probably due to an allergy.

You should see a doctor straight away if:

• You have pain inside your eye

• There is any sudden change in your vision, or

• Light makes your eyes hurt.

These may be signs of a more serious problem. For example it could mean you have glaucoma (raised pressure inside the eye), or an infection elsewhere in your eye.

If you wear contact lenses and you get the symptoms of conjunctivitis, take your contact lenses out and see your doctor. Conjunctivitis needs to be treated quickly if you wear contact lenses. This is because it can cause a more serious eye infection called keratitis.

You should see a doctor straight away if your baby has the symptoms of conjunctivitis. Some bacteria that cause conjunctivitis can cause other serious infections in babies.

Tests to diagnose conjunctivitis

Your doctor will examine your eye with a special lamp. They may also check whether your symptoms have affected how well you can see. There are tests that can tell what is causing your conjunctivitis, although your doctor may decide to treat you without doing a test. This is because the problem usually clears up before the test results would come back.

What treatments work?

Conjunctivitis often clears up on its own. If it doesn't, then the treatment your doctor suggests may depend on what has caused your conjunctivitis. If you have conjunctivitis caused by a bacteria or virus, it may easily be passed to other people, so you must stay away from work, school or nursery. You should avoid close contact with others for as long as your doctor advises. You must also be careful about not sharing towels or bedding with other people.

Allergic conjunctivitis

Mild symptoms

If you have conjunctivitis symptoms at the same time every year, they are probably caused by an allergy. This could be an allergy to pollen. If your symptoms are mild, cold compresses can help. Artificial tears can also help your eyes feel better. Artificial tears are lubricant eye drops that are usually used by people who have very dry eyes. They can help wash away the irritants (for example, pollen) that is causing your allergic conjunctivitis.

Moderate symptoms

For symptoms that are a bit worse, there are several treatments that can help.

Antihistamines are medicines that treat allergies. Antihistamines can be given as eye drops and sometimes as antihistamine tablets. Your doctor may also suggest eye drops that contain medicines called mast cell stabilisers. These drops treat allergies in a similar way to antihistamines.

Eye drops containing vasoconstrictor medicines can reduce the symptoms of allergic conjunctivitis, but they are not suitable for everyone. For example, people with glaucoma (raised pressure inside the eye) and children under 12 should not use them.

Non-steroidal anti-inflammatory drugs (NSAIDs) also come as eye drops. These help reduce inflammation (swelling) in the eyes, that can affect some people with allergic conjunctivitis.

Severe symptoms

People with severe allergic conjunctivitis have symptoms all year round and tend to have more swelling in and around the eyes. If you have severe symptoms your doctor might refer you to an eye specialist.

Eye drops containing steroids (also known as corticosteroids) can help reduce swelling. These can be used together with antihistamines and mast cell stabilisers.

But steroids shouldn't be used over a long time as they can cause serious side effects. For example, if you have wounds in your eyes, steroids can make them take longer to heal. They can also lead to more eye infections, raised pressure in the eyes, and cataracts.

Drops containing ciclospirin may be an option if other treatments don't work. This medicine reduces how well your immune system works. This means that your body doesn't have such a severe allergic reaction to the thing that is causing your conjunctivitis symptoms. But this can also lead to side effects.

Treatments for bacterial conjunctivitis

Conjunctivitis caused by bacteria usually clears up on its own. But antibiotic eye drops can help it clear up more quickly. Your doctor may recommend them if your symptoms are severe and causing you a lot of discomfort.

Bacterial conjunctivitis can sometimes be caused by the sexually transmitted infections gonorrhoea and chlamydia. If you have this type of conjunctivitis your doctor will prescribe antibiotic tablets as well as eye drops.

Treatments for viral conjunctivitis

There is no specific treatment for conjunctivitis caused by a virus. Antibiotics will not help if your conjunctivitis is caused by a virus. But viral conjunctivitis usually clears up on its own after a few days. Many of the treatments that help with allergic conjunctivitis also help with the symptoms of viral conjunctivitis in the meantime. For example cold compresses and artificial tears.

Treatments for conjunctivitis caused by other things

Contact lenses can sometimes cause conjunctivitis by irritating the eyes. They can also carry germs into your eyes. If this happens to you, you should see your doctor right away. This is because conjunctivitis caused by contact lenses can sometimes lead to a more serious infection called keratitis.

Your doctor will tell you that you should stop wearing your lenses for at least two weeks. He or she might prescribe a short course of steroid eye drops or of antibiotic eye drops.

If you get conjunctivitis after using re-usable contact lenses, it's a good idea to switch to single-use lenses. You could also talk to your optician about changing the type of contact lens solution you use.

Exposure to some chemicals can irritate the eyes. You should wash your eyes thoroughly if chemicals make your eyes sore or if chemicals of any kind splash into your eyes. If your symptoms don't improve your doctor may prescribe treatments such as steroid drops or artificial tears.

Some medicines can cause an allergic reaction that can irritate the eyes. The problem should gradually go away once you stop taking the medicine that's causing the problems: for example, if your doctor is able to prescribe a different medicine.

Conjunctivitis and hygiene

Some basic hygiene steps can help relieve your symptoms and reduce the chance of spreading bacterial or viral conjunctivitis to other people.

Hold a clean cloth soaked in warm water over your closed eyes. Don't let anyone else use this cloth. Wash your hands often and don't share towels or pillows.

If you think you have conjunctivitis because of an allergy, try to find out what causes the allergy so you can try to stay away from it.

What will happen to me?

Most people who have conjunctivitis recover completely in two to five days without needing any treatment. It's rare for conjunctivitis to cause serious problems.