Condition library
Eye infections and contagious red eye
Infectious and contagious conditions of the eye surface, eyelids and surrounding tissues.
Medical reviewer Mr Mohamed Mohyudin, Consultant Ophthalmic SurgeonSite-wide clinical review
About this review
Mr Mohyudin completed a clinical review of the site’s medical content on the date shown. This page has been edited since then; a separate sign-off for this exact version has not yet been recorded, so we do not claim one.
Eye infections: compared at a glance
Summaries only — follow each link for symptoms, causes, treatment and when to get urgent help.
| Condition | Part of the eye | In brief |
|---|---|---|
| Conjunctivitis | Conjunctiva | Red, irritated eyes from infection or allergy; the cause guides treatment — viral, bacterial and allergic types need different approaches. |
| Viral conjunctivitis | Conjunctiva | Very contagious watery pink eye, often after a cold; antibiotics do not help — hygiene and time are the main treatment. |
| Bacterial conjunctivitis | Conjunctiva | Sticky yellow-green discharge and glued lids, often needing antibiotic drops after assessment; more urgent in babies and contact-lens wearers. |
| Eye allergies | Conjunctiva | Itchy, red, watery eyes from pollen, dust or pets; seasonal peaks in spring and summer respond well to trigger avoidance and allergy drops. |
| Trachoma | Eyelid, conjunctiva and cornea | A leading infectious cause of blindness worldwide, spread by contact and flies; preventable with hygiene and WHO programmes. |
| Onchocerciasis (river blindness) | Cornea, retina and optic nerve | A parasitic eye disease spread by black flies; a WHO-targeted cause of preventable blindness in affected regions. |
| Endophthalmitis | Vitreous gel and front chamber | Severe infection inside the eye after surgery or injury; a sight-threatening emergency. |
| Orbital cellulitis | Eye socket (orbit) and eyelid | Deep infection around the eye causing painful swelling and often fever; a medical emergency. |
| Dacryocystitis | Tear drainage duct | Infection of the tear sac causing a painful, swollen lump by the nose; needs antibiotics. |
| Herpes eye infection | Cornea | A cold-sore virus infection of the cornea causing a painful red eye; needs prompt antiviral treatment. |
| Shingles in the eye | Eyelid and cornea | Shingles affecting the eye area can threaten sight; the rash and eye pain need urgent specialist care. |
| Fungal eye infection | Cornea | A rare but serious corneal infection, often linked to contact lens wear or eye injury; needs urgent specialist care. |
| Acanthamoeba keratitis | Cornea | A rare but serious corneal infection linked to contact lenses and water exposure; painful red eye needs urgent specialist care. |
| Corneal ulcer | Cornea | An open sore on the cornea, often from infection; a sight-threatening emergency needing urgent care. |
| Blepharitis | Eyelid | Inflamed eyelid margins causing crusting, grittiness and red rims; daily lid hygiene is the mainstay of control. |
| Stye | Eyelid | A painful red lump on the eyelid, usually from a blocked infected lash follicle; warm compresses help most cases settle. |
| Chalazion | Eyelid | A usually painless lump in the eyelid from a blocked oil gland; most clear with warm compresses. |
| Episcleritis | Sclera | A mild, usually painless red eye from surface inflammation; different from the more painful scleritis. |
Frequently asked questions
Is pink eye always bacterial?
No. Most pink eye is viral or allergic. Antibiotics help only when a clinician thinks bacteria are likely.
When is a red eye an infection emergency?
Severe pain, light sensitivity, reduced vision, a contact-lens-related red eye, or painful swelling with fever need urgent assessment.
How do I avoid spreading conjunctivitis?
Wash hands often, avoid sharing towels and pillows, and keep children home while eyes are very red and watery if local guidance advises.