Pink eye (conjunctivitis): symptoms, treatment and how long it lasts

Pink eye is the everyday name for conjunctivitis. NHS inform describes it as a common eye condition that usually gets better in a few weeks without treatment. It happens when the conjunctiva, a thin layer of cells covering the front of the eyes, becomes inflamed.

It usually affects both eyes. The conjunctiva can become inflamed for several different reasons, which is why the advice on treatment and spreading depends on the cause.

The NHS says conjunctivitis usually affects both eyes and makes them red, burn or feel gritty, produce pus that sticks to the lashes, itch and water. NICE CKS describes the typical features as redness, discomfort that may feel like grittiness, a foreign body or a burning sensation, and watering and discharge that may blur vision briefly or stick the lids together on waking.

The look of the eyes can give a clue to the cause, as summarised below.

The NHS says treatment depends on the cause. If it is a bacterial infection you might be prescribed antibiotics, but these will not work if it is caused by a virus or an allergy. NICE CKS notes it is difficult to tell viral and bacterial conjunctivitis apart clinically, that most cases are self-limiting, and that topical antibiotics are used judiciously, sometimes with a delayed treatment strategy.

The NHS suggests several things you can do yourself. These ease symptoms whatever the cause.

• Wash your eyelids with clean water: boil water and let it cool, then gently wipe the eyelashes with a clean cotton wool pad to clear crusts, using a separate piece for each eye.

• Hold a cold flannel on your eyes for a few minutes to cool them.

• Do not wear contact lenses until your eyes are better.

• Ask a pharmacist for advice. The NHS says they can suggest eyedrops or antihistamines. NHS inform also mentions lubricant eye drops from pharmacies.

• For a child under 2 years, the NHS says treatment needs a prescription from a GP.

• Allergic conjunctivitis can usually be treated with antihistamines and, if possible, avoiding the trigger (NHS inform).

The NHS says conjunctivitis usually gets better in a couple of weeks without treatment, and NHS inform says within a few weeks. NICE CKS gives more detail for infective cases: viral conjunctivitis usually resolves within 7 days, and bacterial conjunctivitis typically resolves within 5 to 10 days. NICE CKS also says epidemic keratoconjunctivitis caused by adenoviruses can lead to visual loss and light sensitivity, which is one reason persistent symptoms should be checked.

The NHS says to see a GP if your symptoms have not cleared up within 7 days. NHS inform sets the point at 2 weeks and advises contacting an optometrist. Conjunctivitis caused by some sexually transmitted infections takes longer to get better.

The NHS says infectious conjunctivitis that produces sticky pus is contagious, and that red, gritty eyes are also usually contagious. Conjunctivitis caused by allergies, such as hay fever, makes eyes red and watery but is not contagious.

The NHS lists what helps stop it spreading, summarised below.

• Wash your hands regularly with warm soapy water.

• Wash pillow cases and face cloths in hot water and detergent.

• Cover your mouth and nose when sneezing and put used tissues in the bin.

• Do not share towels and pillows, and do not rub your eyes.

• You do not need to stay away from work or school unless you or your child are feeling very unwell.

NHS inform says the 3 most common causes are infection (infective conjunctivitis), an allergic reaction (allergic conjunctivitis) and something irritating the conjunctiva, such as a loose eyelash (irritant conjunctivitis).

NICE CKS says viral conjunctivitis is the most common infectious type, with most cases caused by adenoviruses. The most common bacterial causes are Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae. Allergic conjunctivitis includes seasonal types, associated with pollen, and perennial types, associated with house dust mites, mould spores or animal dander.

Babies need extra care. The NHS says to see a GP if your baby has red, sticky eyes, and to get an urgent appointment, or help from NHS 111, if your baby is less than 30 days old. NHS inform sets the cut-off at 28 days. NICE CKS says conjunctivitis in the first four weeks of life (ophthalmia neonatorum) can be infectious or non-infectious, and that untreated infection can lead to serious complications, including sight loss.

If you wear contact lenses, the NHS says to see a GP if you have conjunctivitis symptoms as well as spots on your eyelids, because you might be allergic to the lenses. NHS inform adds that you should not wear contact lenses until symptoms have cleared, and should not re-use old lenses after the infection has gone because they could cause re-infection. NICE CKS notes contact lens wearers have the greatest risk of complications such as keratitis.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have any of the following, as they can be signs of a more serious eye problem. NHS inform advises contacting your optometrist urgently, and phoning 111 if the optometrist is closed.

• Pain in your eyes.

• Sensitivity to light.

• Changes in your vision, like wavy lines or flashing.

• Very red eyes, in one or both eyes.

• A baby less than 30 days old (28 days according to NHS inform) with red, sticky eyes.

Most people will need only self-care and, if wanted, advice from a pharmacist. The NHS points to pharmacists for eyedrops or antihistamines, a GP for a baby, for symptoms not clearing within 7 days or for contact lens problems, and NHS 111 or an urgent appointment for warning signs. NHS inform says to contact an optometrist if symptoms are urgent.

Some people choose to see a private optometrist or eye specialist for a quicker assessment. In general terms the same distinctions apply: working out whether the cause is infective, allergic or something more serious, and arranging referral to ophthalmology where needed. NICE CKS lists reasons for urgent ophthalmology referral, including a serious cause of red eye, suspected gonococcal or chlamydial infection, possible herpes infection, severe disease with corneal involvement and recent eye surgery.