Conjunctivitis, often called pink eye, is one of the most common reasons people visit a UK pharmacy or GP with an eye problem. It's usually not serious, but telling the three main types apart matters, because the right treatment for one does nothing for another. This guide explains how to recognise each type, what actually helps, and the handful of symptoms that mean you shouldn't just treat it yourself.
Most pharmacies in the UK now manage straightforward conjunctivitis directly, without a GP referral, as part of the wider shift towards pharmacist-led care for common minor ailments. That makes it one of the quicker conditions to get sorted, provided the type is correctly identified first. Getting the diagnosis right at the outset avoids the common mistake of reaching for leftover antibiotic drops for what's actually an allergy, or vice versa.
What causes conjunctivitis: bacterial, viral and allergic
Conjunctivitis is inflammation of the conjunctiva, the thin, clear membrane that covers the white of the eye and lines the inside of the eyelid. When it becomes inflamed, the tiny blood vessels within it become more visible, giving the eye its characteristic pink or red appearance. There are three main causes, and they behave quite differently:
- Bacterial conjunctivitis: caused by bacteria such as Staphylococcus or Streptococcus species, often producing a thick, sticky yellow or green discharge that can make the eyelids stick together, especially after sleep.
- Viral conjunctivitis: usually caused by the same viruses responsible for colds, and frequently appears alongside or just after one. It tends to produce a watery discharge and a gritty feeling, and is the most contagious of the three types.
- Allergic conjunctivitis: triggered by an allergen such as pollen, dust mites or pet hair, rather than an infection. It typically affects both eyes at once and causes intense itching alongside watery discharge, often alongside other hay fever symptoms.
Working out which type you have matters, because treatment differs significantly between them: using the wrong one, for example antibiotic drops for an allergic reaction, won't help and can delay the right treatment.
There's also a seasonal pattern worth knowing. Viral and bacterial conjunctivitis tend to cluster in the colder months alongside colds and other respiratory infections, and spread more easily in nurseries, schools and shared households. Allergic conjunctivitis, by contrast, tracks pollen and other seasonal allergens, so it tends to flare in spring and summer for people with hay fever, or all year round for those sensitive to dust mites or pet dander.
Symptoms: how to tell which type you might have
The type of discharge and the pattern of symptoms usually point to a likely cause, though a pharmacist or GP can help if you're unsure:
- Bacterial: thick yellow or green discharge, eyelids crusted or stuck together on waking, usually starts in one eye and often spreads to the other within a few days.
- Viral: watery discharge, a gritty or burning feeling, redness that can be quite marked, and often a history of a recent cold or contact with someone else who has conjunctivitis.
- Allergic: watery discharge with intense itching rather than grittiness, puffy eyelids, and usually affects both eyes from the start, often alongside sneezing or a runny nose.
Some overlap is normal, and it's possible to have more than one trigger at once, for example hay fever alongside a minor bacterial infection. If you're not sure which type you have, or symptoms aren't settling with simple measures, it's worth getting a pharmacist or clinician's opinion rather than guessing.
Treating bacterial conjunctivitis
Bacterial conjunctivitis is usually treated with chloramphenicol eye drops or ointment, a widely used first-line antibacterial treatment. In many cases this can be bought directly from a UK pharmacy for mild, straightforward presentations, or supplied after a short consultation with a pharmacist or online clinician who can confirm the diagnosis and check it's the right choice for you.
Drops are usually used every two hours for the first couple of days, then four times a day, while the ointment is applied less often, commonly at night. Most people notice improvement within 2 to 3 days, and the full course is usually continued for 5 days even if symptoms clear sooner, to reduce the chance of the infection coming back.
It's also worth knowing that many cases of mild bacterial conjunctivitis settle on their own within a week or two even without antibacterial treatment, since the immune system clears most straightforward infections unaided. Treatment is still usually recommended because it speeds up recovery, reduces how long someone is contagious for, and lowers the small risk of it spreading to the other eye or to other people in the household.
Treating allergic conjunctivitis
Allergic conjunctivitis responds to antihistamine eye drops rather than antibiotics. Azelastine eye drops work relatively quickly, often within minutes, and can be used as needed when symptoms flare. Sodium cromoglicate works differently: it stabilises the cells that trigger the allergic reaction, but needs to be used regularly, usually four times a day, and can take up to two weeks to reach its full effect, so it suits ongoing or predictable triggers like pollen season better than a sudden flare.
If allergic conjunctivitis is part of a wider hay fever picture, an oral antihistamine taken alongside the eye drops often helps more than either alone. Avoiding the trigger where practical, for example wraparound sunglasses outdoors during pollen season or reducing contact with pets, also reduces how often symptoms occur.
Viral conjunctivitis and self-care that helps all types
Viral conjunctivitis has no specific treatment: antibiotics don't work against it, and antiviral eye drops aren't used for the common viruses responsible. It's also the most contagious of the three types, often spreading easily within households, schools and workplaces, so good hygiene matters more here than for the other causes. Wash your hands frequently, avoid touching or rubbing your eyes, and don't share towels, pillows or eye make-up while symptoms last.
Regardless of the cause, a few self-care measures help comfort while the underlying problem settles:
- Bathe the eyes gently with cooled, boiled water and a clean piece of cotton wool for each eye, wiping away any crusting or discharge.
- A warm compress can ease crusting and discomfort from bacterial or viral conjunctivitis, while a cool compress tends to suit the itching of allergic conjunctivitis better.
- Lubricating eye drops (artificial tears) can soothe grittiness and discomfort whatever the cause.
- Stop wearing contact lenses until your eyes have been completely clear and symptom-free for at least 24 hours, and throw away any lenses, cases or solution used while you had symptoms.
Viral conjunctivitis usually resolves within one to two weeks without any specific treatment, though it can occasionally take a little longer, particularly if both eyes are affected in sequence. It's common for symptoms to look and feel worse before they improve, typically peaking around days 3 to 5, which can understandably prompt a pharmacy visit even though no treatment will speed things up at that stage. If you're also dealing with a sinus infection or a cold that isn't settling, that's worth addressing separately too.
When to see a doctor urgently
Most conjunctivitis is straightforward and settles with pharmacy treatment or on its own. A smaller number of presentations need same-day medical assessment, usually from a GP, an optometrist, or an eye casualty department, because they can indicate a more serious problem than simple conjunctivitis:
- Significant eye pain, rather than mild irritation or grittiness
- Sensitivity to light (photophobia)
- Reduced or blurred vision that doesn't clear with blinking
- One very red eye together with a headache or feeling generally unwell
- A newborn baby with a red, sticky or swollen eye
- Contact lens wearers with a painful red eye, which can signal a more serious corneal infection rather than straightforward conjunctivitis
If any of these apply, don't wait for a routine pharmacy consultation; seek urgent assessment the same day. Outside of these red flags, if symptoms haven't started improving after a few days of appropriate treatment, it's reasonable to get a follow-up opinion to check the diagnosis and treatment are right for you. The same general principle applies to other common infections, including ear infections (otitis externa), where self-care helps most cases but a minority need clinical review.