Conjunctivitis is a condition that occurs when the conjunctiva (a thin layer of cells covering the front of your eyes) becomes inflamed.

The three most common causes of this inflammation are:

• infection (infective conjunctivitis)
• an allergic reaction (allergic conjunctivitis)
• something irritating the conjunctiva, such as a loose eyelash (irritant conjunctivitis)

These are discussed in more detail below.

Infective conjunctivitis

Eye infections are most commonly caused by:

• bacteria, for example the strains of bacteria that more commonly cause lung and ear infections
• a virus, most commonly an adenovirus that may also cause a sore throat and high temperature (fever)
• sexually transmitted infections such as chlamydia or gonorrhoea

Viral conjunctivitis causes a watery discharge while the discharge from bacterial conjunctivitis contains pus. An eye swab can also determine the cause of the infection (read more about diagnosing conjunctivitis).

Spreading the infection

You are more likely to develop infective conjunctivitis if you have been in close contact with someone who is already infected with it.

It is therefore very important to wash your hands thoroughly after coming into contact with anyone who has infective conjunctivitis. Don’t share pillows or towels with anyone with the infection.

Risk groups

You may be more at risk of infective conjunctivitis if:

• You are old or young: the condition is more common in children and the elderly, possibly because children come into contact with more infections at school and elderly people may have a weaker immune system.
• You have recently had an upper respiratory tract infection, such as a cold.
• You have diabetes or another condition that weakens your immune system (as you may be more prone to infections).
• You are taking corticosteroids (steroids), as this medication can weaken your immune system.
• You have blepharitis (inflammation of the rims of the eyelids), which can be caused by a bacterial infection and may lead to conjunctivitis.
• You have been in a crowded place, such as a busy train.

Allergic conjunctivitis

Allergic conjunctivitis is caused when your eyes come into contact with an allergen. An allergen is a particular substance that causes your immune system to react abnormally. This is known as an allergic reaction.

There are four main types of allergic conjunctivitis:

• seasonal allergic conjunctivitis
• perennial allergic conjunctivitis
• contact dermatoconjunctivitis
• giant papillary conjunctivitis

Seasonal and perennial conjunctivitis

Seasonal and perennial allergic conjunctivitis are usually caused by:

• pollen from grass, trees or flowers
• dust mites
• flakes of dead animal skin

These types of conjunctivitis are more common among people who also have other allergies, such as asthma, and often occur with allergic rhinitis (an allergy that affects the nose, causing sneezing and a blocked or runny nose).

Contact dermatoconjunctivitis

Contact dermatoconjunctivitis is usually caused by eye drops, but it can also be caused by make-up or chemicals.

Giant papillary conjunctivitis

Giant papillary conjunctivitis is caused by:

• contact lenses
• stitches (sutures) used in eye surgery
• a prostheses (artificial) part of the eye that is fitted during eye surgery

Giant papillary conjunctivitis is estimated to affect around 1%-5% of people who use soft contact lenses and 1% of people who use hard contact lenses.

Irritant conjunctivitis

Irritant conjunctivitis can have a wide range of potential causes. Some common causes include:

• chlorinated water used in swimming baths
• shampoo
• a stray eyelash rubbing against the conjunctiva
• smoke or fumes

Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and others are good for you.

Conjunctiva

The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

Immune system

The immune system is the body’s defence system, which helps protect it from disease, bacteria and viruses.

Inflammation

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.

Respiratory tract

The respiratory tract is a general term that is used to describe all the parts of the body involved in helping a person to breathe.

Complications with conjunctivitis depend on whether the condition is an infection (infective conjunctivitis) or an allergic reaction (allergic conjunctivitis).

Infective conjunctivitis

If your infection has been caused by a sexually transmitted infection (STI), especially chlamydia, your conjunctivitis may last for several months rather than weeks.

Infective conjunctivitis caused by any type of bacteria can cause a number of complications, particularly in babies born prematurely (before week 37 of pregnancy).

Possible complications include:

• Meningitis: an infection of the meninges (the protective layer of cells surrounding the brain and spinal cord).
• Cellulitis: an infection of the deep layer of skin and tissue that causes the skin on the surface to become sore and inflamed (swollen). It is usually easily treated with antibiotics.
• Septicaemia: this is more commonly known as blood poisoning. This condition occurs when bacteria get into the bloodstream and attack the body’s tissues.
• Otitis media: this is a short-term ear infection. It affects around one-in-four children who have had infective conjunctivitis caused by the haemophilus influenzae bacteria.

Neonatal conjunctivitis

In newborn babies (neonates) who are up to 28 days old, infective conjunctivitis can lead to a severe and rapidly progressive eye infection. If this is not treated, it can result in permanent damage to your child’s vision.

If your newborn baby is found to have infective conjunctivitis, they will be referred immediately for specialist assessment and treatment. Their condition will be closely monitored. Complications are rare and most babies make a full recovery from infective conjunctivitis.

After having infective conjunctivitis caused by chlamydia, around one-in-five babies may develop pneumonia. This is a potentially life-threatening condition in young babies and may require treatment in hospital.

Allergic conjunctivitis

If your conjunctivitis is due to an allergic reaction to pollen, dust mites or similar (seasonal and perennial allergic conjunctivitis), it is very rare to experience any serious complications.

However, you may find your reoccurring symptoms frustrating. For example, if your conjunctivitis is caused by pollen, you may find it difficult to go outside during the spring and summer months without triggering your symptoms.

This type of allergic conjunctivitis can affect your daily life and could make it difficult for you to concentrate at work or school, particularly if your eyes are severely irritated. Although this can affect your quality of life, it should not cause any long-term health problems. Read more about living with an allergy.

Punctate epithelial keratitis

Some types of conjunctivitis can cause a condition called keratitis. Keratitis is where your cornea (the front of your eye) becomes inflamed (swollen).

This can be painful and make your eyes sensitive to light (photophobia). Sometimes, ulcers form on the cornea. If the ulcers scar your cornea, your vision may be permanently damaged.

Contact your GP immediately if you experience any unusual symptoms (read more about the symptoms of conjunctivitis) or visit your nearest accident and emergency (A&E) department.

Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and others are good for you.

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Conjunctiva

The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

Inflammation

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.

Lungs

The lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.

Your GP should be able to diagnose conjunctivitis by asking about your symptoms and examining your eyes.

It can be helpful to describe to your GP how your conjunctivitis started as this will help them diagnose which type it is and whether it needs to be treated.

The most common symptoms of infective conjunctivitis are sticky, red and watery eyes. However, infective conjunctivitis can sometimes be confused with other types of conjunctivitis, which are treated differently.

Swab test

Your GP may suggest further tests (such as a swab test) if your conjunctivitis hasn’t responded to treatment or to help decide what treatment to use.  

A swab looks similar to a small cotton bud. It’s used to collect a small sample of mucus from your infected eye, which is sent to a laboratory to find out the cause of your conjunctivitis.

Find out more about treatments for infective conjunctivitis.

If your symptoms are severe or do not respond to treatment, you may need to see an eye specialist (ophthalmologist).

Other conditions

Most cases of conjunctivitis clear within one to two weeks, sometimes sooner, without needing any medical treatment. In some cases it can last for longer than two weeks, which is known as persistent infective conjunctivitis.

If you have any unusual symptoms such as severe pain, blurred vision or sensitivity to light, these may mean that you have a more serious condition.

If you have any of these symptoms, it is very important to seek medical assistance immediately, either by contacting your GP or visiting a hospital.

Other more serious conditions include:

• Acute glaucoma: this rare form of glaucoma causes a painful build-up of pressure in your eye.
• Keratitis: this is when your cornea (the clear layer at the front of your eye) becomes swollen and develops open sores.
• Iritis: this is a type of uveitis (swelling of the middle layer of your eye) that causes pain, headaches and watery eyes.

Newborn babies

Contact your GP straight away if you think your baby may have infective conjunctivitis (also called neonatal conjunctivitis).

If this is not possible, call NHS 111 or your local out-of-hours service. Your GP will examine your baby closely to see if they have sticky eyes or infective conjunctivitis.

Any newborn baby with infective conjunctivitis must be referred to an eye specialist straight away for treatment.

Find out more about the symptoms of infective conjunctivitis.

Conjunctiva

The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

Inflammation

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.

Conjunctivitis is a common condition that causes redness and inflammation of the thin layer of tissue that covers the front of the eye (the conjunctiva).

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 eye at first, but usually affects both eyes after a few hours.

What causes conjunctivitis?

The conjunctiva can become inflamed 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.

Treating conjunctivitis

Conjunctivitis often doesn’t require treatment as the symptoms usually clear up within a couple of weeks. If treatment is necessary, the type of treatment will depend on the cause. In severe 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 eyelids or lashes can be cleansed with cotton wool and water.

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 

Work and school

Public Health England advises that you do not need to stay away from work or school if you or your child has conjunctivitis, unless you are feeling particularly unwell.

If there are a number of cases of conjunctivitis at one school or nursery, you may be advised to keep your child away from the school until their infection has cleared up.

Generally, adults who work in close contact with others, or share equipment such as phones and computers, should not return to work until the discharge has cleared up.

Complications

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 rare but when they do occur they can be serious and include:

• 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.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: red eye

The symptoms of conjunctivitis will depend on the cause, but generally they include:

• eye redness: this happens as a result of the inflammation and widening of the tiny blood vessels in the conjunctiva (thin layer of cells that covers the front of the eyes)
• watering eyes: the conjunctiva contains thousands of cells that produce mucus and tiny glands that produce tears – inflammation causes the glands to become overactive, so that they water more than usual

Although only one eye tends to be affected at first, symptoms usually affect both eyes within a few hours.

Infective conjunctivitis

If you have infective conjunctivitis you may also have:

• a burning sensation in your eyes
• a feeling of grit in your eyes
• a sticky coating on the eyelashes – usually when you first wake in the morning
• an enlarged lymph node in front of the ear

Allergic conjunctivitis

You may also have itchy eyes if you have allergic conjunctivitis.  

The pattern of symptoms for allergic conjunctivitis depends on the substance you are allergic to.

Allergies to pollen (hay fever) occur during certain parts of the year. You can have an allergy to:

• tree pollen, released during spring
• grass pollen, released during the end of spring and beginning of summer
• weed pollen, released any time from early spring to late autumn

It is highly likely that the pollen will also cause other symptoms such as sneezing and a runny or blocked nose.

Allergies to dust mites or animal fur cause symptoms throughout the year. Both eyes are usually affected and you may find the symptoms worse in the morning.

Some people develop an allergy to eye drops. This is known as contact dermatoconjunctivitis and can also affect your eyelids, causing them to become dry and sore.

Some people are allergic to wearing contact lenses, which is known as giant papillary conjunctivitis. The symptoms progress much more slowly and you may also develop small spots on the inside of your upper eyelids. This type of conjunctivitis carries a high risk of complications so you need to get medical advice.

Read more information about allergies.

When to seek medical advice

Most cases of conjunctivitis are not a cause for concern but you should contact your GP if you think you have it – especially if you think the conjunctivitis is related to wearing contact lenses.

Your GP will be able to check whether there is a more serious underlying cause of your symptoms.

When to seek immediate medical advice

The following symptoms could be the sign of a more serious eye condition:

• pain in your eyes
• sensitivity to light (photophobia)
• disturbed vision
• intense redness in one or both of your eyes

If you experience any of these symptoms, contact your GP immediately. If this isn’t possible, visit your nearest accident and emergency (A&E) department.

Conjunctiva

The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

Immune system

The immune system is the body’s defence system, which helps protect it from disease, bacteria and viruses.

Inflammation

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.

Respiratory tract

The respiratory tract is a general term that is used to describe all the parts of the body that are involved in helping a person to breathe.

The recommended treatment for conjunctivitis will depend on whether it is caused by infection, an allergic reaction or an irritant such as a stray eyelash.

Each treatment option is discussed in more detail below.

Infective conjunctivitis

Most cases of infective conjunctivitis do not require medical treatment and will clear up in one to two weeks.

Self-care

There are several ways that you can treat infective conjunctivitis at home. The following advice should help ease your symptoms:

• Remove your contact lenses. If you wear contact lenses, take them out until all the signs and symptoms of the infection have gone. Avoid using contact lenses until 24 hours after you have finished a course of treatment. Do not re-use the lenses after the infection has passed as the old lens could be a potential source of re-infection.
• Use lubricant eye drops. These are available over the counter at pharmacies or they may be prescribed for you. They may help ease any soreness and stickiness in your eyes. Always follow the manufacturer’s instructions.
• Gently clean away sticky discharge from your eyelids and lashes using cotton wool soaked in water.
• Wash your hands regularly. This is particularly important after you have touched your infected eyes and will stop the infection spreading to other people.

Antibiotics

Antibiotics are not usually prescribed for infective conjunctivitis as it usually clears up by itself and there is a very low risk of complications for untreated conjunctivitis.

However, if the infection is particularly severe or it has lasted for more than two weeks, you may be prescribed antibiotics. Some schools or playgroups may insist that a child is treated with antibiotics before they can return, although this is rarely necessary.

The two main types of antibiotics that may be prescribed are:

• chloramphenicol
• fusidic acid

Chloramphenicol

Chloramphenicol is usually the first choice and comes in the form of eye drops.

Make sure you follow your doctor’s advice about how and when to use the eye drops, or check the instructions that come with the medication so you know how to use them properly.

If eye drops are not suitable for you, you may be prescribed the antibiotic as an eye ointment instead.

Fusidic acid

Fusidic acid may be prescribed if chloramphenicol is not suitable for you. It’s often better for children and elderly people as it doesn’t need to be used as often. It is also the preferred treatment for pregnant women.

Like chloramphenicol, fusidic acid comes in the form of eye drops and should be used as advised by your doctor or as described in the instructions that come with the medication.

Side effects

Eye drops can briefly cause blurred vision. Avoid driving or operating machinery straight after using eye drops.

Chloramphenicol and fusidic acid can also cause some other side effects, such as a slight stinging or burning sensation in your eye. This feeling should not last long.

Further treatment

If you still have symptoms after two weeks, it is very important to go back to your GP. Also contact your GP immediately if you experience any of the following symptoms:

• eye pain
• sensitivity to light (photophobia)
• loss of vision
• intense redness in one or both of your eyes

Your GP may suggest that you are tested for sexually transmitted infections (STIs). Some STIs, such as chlamydia, can cause infective conjunctivitis. In this case, your symptoms may last for several months.

Allergic conjunctivitis

Your treatment will depend on which type of allergic conjunctivitis you have.

The four main types of allergic conjunctivitis are:

• seasonal conjunctivitis: typically caused by an allergy to pollen
• perennial conjunctivitis: usually caused by an allergy to dust mites or pets
• contact dermatoconjunctivitis: usually caused by an allergy to eye drops or cosmetics
• giant papillary conjunctivitis: usually caused by an allergy to contact lenses

Whatever the cause, you will find that some self-help methods can ease your symptoms.

Self-help

If you have allergic conjunctivitis, you can follow the guidelines below to treat your condition at home:

• Remove your contact lenses. If you wear contact lenses, take them out until all the signs and symptoms of the conjunctivitis have gone.
• Do not rub your eyes, even though your eyes may be itchy. Rubbing them can make your symptoms worse.
• Place a cool compress over your eyes.
• Wetting a flannel with cool water and holding it over your eyes will help ease your symptoms.
• Avoid exposure to the allergen, if possible.

Seasonal and perennial allergic conjunctivitis

If you have seasonal or perennial conjunctivitis you may be prescribed the following medicines:

• antihistamines
• mast cell stabilisers
• corticosteroids

These are described in more detail below.

Antihistamines

If your allergic conjunctivitis requires rapid relief, your GP will probably prescribe a medicine known as an antihistamine.

Antihistamines work by blocking the action of the chemical histamine, which the body releases when it thinks it is under attack from an allergen. This prevents the symptoms of the allergic reaction from occurring.

Antihistamine eye drops

You may be prescribed antihistamine eye drops, such as:

• azelastine (not suitable for children under four years of age)
• emedastine (not suitable for children under three years of age)
• ketotifen (not suitable for children under three years of age)
• antazoline with xylometazoline (Otrivine-Antistin, not suitable for children under 12 years of age)

Antazoline with xylometazoline (Otrivine-Antistin) is also available over the counter from pharmacies without prescription. Always follow the manufacturer’s instructions.

If you are pregnant or breastfeeding, some antihistamine eye drops may not be suitable. Speak to your GP for advice.  

Oral antihistamines

You may be prescribed an antihistamine such as:

• cetirizine
• fexofenadine
• loratadine

You will usually only have to take an antihistamine once a day.

If possible, oral antihistamines should not be taken if you are pregnant or breastfeeding. Speak to your GP for advice.

Although new antihistamines should not make you drowsy, they may still have a sedating effect. This is more likely if you take high doses or drink alcohol while you are taking antihistamines.

Mast cell stabilisers

Mast cell stabilisers are an alternative type of medicine. Unlike antihistamines, they will not provide rapid relief from your symptoms, but they are more effective at controlling your symptoms over a longer period of time.

It may take several weeks to feel the effects so you may also be prescribed an antihistamine to take at the same time.

Mast cell stabilisers that are commonly prescribed in the form of eye drops include:

• lodoxamide
• nedocromil sodium
• sodium cromoglicate

Corticosteroids

If your symptoms of allergic conjunctivitis are particularly severe, you may be prescribed a short course of topical corticosteroids (a cream, gel or ointment). However, these are not usually prescribed unless absolutely necessary.

Read more about corticosteroids.

Giant papillary conjunctivitis

As giant papillary conjunctivitis is usually caused by contact lenses, the symptoms often clear up after you stop wearing them. The spots that form on the inside of your upper eyelid may last slightly longer.

If you develop giant papillary conjunctivitis as a result of recent eye surgery, you will be immediately referred to an ophthalmologist. This is to ensure that your eyes can be carefully monitored and the most effective treatment given.

Irritant conjunctivitis

Most cases of irritant conjunctivitis do not require any treatment as the condition should clear up once the irritant is removed from the eye.

An exception to this is if your eyes were exposed to harmful substances such as bleach or acid. This is usually regarded as medical emergency and you will need to be admitted to hospital so your eyes can be washed out with saline solution.

Antibiotics

Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi.

Bacteria

Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some others are good for you.

Conjunctiva

The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

Inflammation

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.