Conjunctivitis
Symptoms, Causes & Treatment
Understanding conjunctivitis: how to identify viral, bacterial, and allergic types, when it needs urgent assessment, and the most effective treatments.
What Is Conjunctivitis?
Conjunctivitis (inflammation of the conjunctiva) is one of the most common eye conditions in the UK, affecting people of all ages. It causes redness, discharge, and discomfort and is frequently self-limiting.
The three main types have distinct features: viral conjunctivitis is highly contagious and self-resolving; bacterial conjunctivitis produces a mucopurulent discharge and responds to antibiotic drops; allergic conjunctivitis causes intense itching and is treated with antihistamine eye drops.
Conjunctivitis with reduced vision, pain on eye movement, or photophobia is not simple conjunctivitis — it requires same-day urgent ophthalmology assessment to exclude keratitis or uveitis.
What Are the Symptoms of Conjunctivitis?
The discharge pattern, itching, and bilateral vs unilateral involvement help distinguish the three main types of conjunctivitis.
Pink or red eye · Watery or purulent discharge · Crusting of lashes on waking · Gritty or foreign body sensation · Both eyes often affected · Itching (allergic) or burning (viral) · No visual loss or pain in uncomplicated conjunctivitis
Conjunctivitis with reduced vision, severe pain, or photophobia (possible keratitis or uveitis) · Neonatal conjunctivitis within first 28 days of life · Gonococcal conjunctivitis (profuse purulent discharge) — same-day emergency
If conjunctivitis is accompanied by reduced vision, significant pain, photophobia, or a fixed pupil, attend A&E immediately. These symptoms indicate something more serious than conjunctivitis. Contact lens wearers with a red eye should always attend A&E as a priority.
What Causes Conjunctivitis?
Conjunctivitis is caused by viruses, bacteria, or allergens. Each type has distinct features, transmission patterns, and appropriate treatment.
Conjunctivitis can be viral (adenovirus — most common, highly contagious), bacterial (Staph aureus, H. influenzae, N. gonorrhoeae), or allergic (IgE-mediated, seasonal). Treatment differs fundamentally by type.
Blepharitis is a chronic condition caused by Staph aureus infection of lid margins, seborrhoeic dermatitis, or meibomian gland dysfunction. It is the most common eye condition seen in primary care and often coexists with dry eye.
Cataracts cause gradual clouding of the lens, producing progressive blurring, glare, and halos. Cataract extraction is the most commonly performed surgical procedure in the UK and is highly effective.
Age-related macular degeneration (AMD) affects central vision. Wet AMD causes rapid central vision loss from neovascularisation and requires emergency anti-VEGF injection. Dry AMD progresses slowly.
Acute angle-closure glaucoma causes sudden severe eye pain, nausea, red eye, and halos around lights. It is caused by sudden blockage of aqueous drainage. This is an ocular emergency requiring immediate ophthalmology treatment.
Uveitis is inflammation of the uveal tract (iris, ciliary body, choroid). It presents with eye pain, photophobia, and circumcorneal injection. It is associated with HLA-B27 conditions including ankylosing spondylitis.
Key Risk Factors
How Is Conjunctivitis Diagnosed?
Conjunctivitis is diagnosed clinically. Conjunctival swab is taken for suspected bacterial or STI conjunctivitis. Neonatal conjunctivitis always requires swab. Visual acuity and slit-lamp assessment exclude keratitis or uveitis.
How Is Conjunctivitis Treated?
Viral conjunctivitis is self-limiting (no treatment needed). Bacterial conjunctivitis is treated with chloramphenicol drops. Allergic conjunctivitis requires antihistamine drops. Gonococcal conjunctivitis requires IV ceftriaxone.
Supportive Measures
Clean discharge from lids with cooled boiled water and clean cotton wool, from the inner to outer corner. Viral conjunctivitis: artificial tears, cold compresses. Allergic conjunctivitis: remove allergen, cold compresses, antihistamine drops. Do not wear contact lenses. Do not share towels.
Recurrent Conjunctivitis
Recurrent allergic conjunctivitis requires allergen identification and avoidance, year-round antihistamine drops, and possibly immunotherapy. Recurrent bacterial conjunctivitis in a contact lens wearer requires full lens hygiene review. Chlamydial conjunctivitis requires sexual health assessment and partner treatment.
When Should You Seek Medical Advice for Conjunctivitis?
Neonatal conjunctivitis within 28 days of birth · Conjunctivitis with reduced vision, significant pain, or photophobia · Contact lens wearer with conjunctivitis · Suspected gonococcal conjunctivitis with profuse discharge. All require urgent assessment.
Conjunctivitis not improving after 5 days of antibiotic drops · Newborn with eye discharge in first month of life · STI-related conjunctivitis · You wear contact lenses and have developed a red eye.
How Can You Prevent Conjunctivitis?
Infectious conjunctivitis is highly contagious. These measures prevent spread and reduce the risk of recurrence.
Wash hands before touching eyes. Do not share towels, pillowcases, or eye make-up during conjunctivitis. Viral conjunctivitis is highly contagious. Stay away from school or work until discharge has resolved.
Warm compresses applied to closed eyelids for 2 minutes twice daily improve meibomian gland function, reduce dry eye symptoms, and prevent blepharitis flares. This should become a daily habit.
Never sleep in contact lenses. Clean lenses strictly as directed. Replace on schedule. Use sterile solution, not tap water. Contact lens keratitis can cause permanent vision loss within 24 hours.
All diabetics should attend annual NHS diabetic eye screening (dilated fundal photography) to detect diabetic retinopathy before it causes irreversible vision loss. This is free and highly effective.
Attend regular NHS sight tests (free every 2 years on the NHS, more frequently if you are diabetic, over 60, or have glaucoma in the family). Eye tests detect glaucoma, retinal disease, and AMD before symptoms appear.
Wear UV400-protective sunglasses outdoors. UV exposure increases the risk of cataracts and AMD. Polarised lenses do not provide additional UV protection unless UV400-rated.
Speak to a Clinician About Conjunctivitis
Through The GP Service, a clinician can assess your red eye, prescribe appropriate antibiotic drops for bacterial conjunctivitis, and advise on isolation and hygiene.
Expert clinical advice, when you need it.
Conjunctivitis FAQs
Viral conjunctivitis is highly contagious. Wash hands frequently. Do not share towels, pillowcases, or eye makeup. Avoid touching the eye. Stay away from school or work until discharge has cleared (typically 3–5 days). Discard eye makeup used during the infection.
Viral conjunctivitis resolves spontaneously in 1–2 weeks without treatment. Bacterial conjunctivitis resolves faster with antibiotic eye drops (chloramphenicol). Allergic conjunctivitis requires antihistamine eye drops and allergen avoidance. Artificial tears provide symptomatic relief for all types.
Neonatal conjunctivitis (ophthalmia neonatorum) within the first 28 days of life requires urgent assessment. Gonococcal neonatal conjunctivitis can cause blindness within 24–48 hours and is a paediatric emergency.
Contact lens wearers who develop conjunctivitis should remove lenses immediately and not re-insert until the infection has fully resolved. Contact lens keratitis (corneal infection) is a serious complication requiring urgent A&E assessment.
Gonococcal conjunctivitis causes profuse mucopurulent discharge and rapid-onset severe conjunctival inflammation. It is an emergency requiring same-day IV ceftriaxone, sexual health referral, and partner notification. Chlamydial conjunctivitis is more indolent, presenting with chronic follicular conjunctivitis.
Conjunctivitis that does not clear within 2 weeks, is associated with vision changes, photophobia, pain on eye movement, or marked redness with a fixed pupil requires urgent clinical assessment to exclude keratitis, uveitis, or acute glaucoma.
Allergic conjunctivitis is treated with antihistamine eye drops (azelastine, olopatadine). Mast cell stabiliser drops (sodium cromoglicate) are preventive. Systemic antihistamines also help. Cold compresses provide immediate symptomatic relief.
Trachoma (Chlamydia trachomatis) is the leading infectious cause of blindness globally but is rare in the UK. It causes chronic follicular conjunctivitis, corneal scarring, and trichiasis. It is treated with azithromycin and is a public health notifiable disease.