Infectious conjunctivitis
Conjunctival inflammation of viral or bacterial origin. Viral cases account for 80 % in adults and self-resolve in 7–14 days. Bacterial cases receive a short course of topical antibiotics. Histamine is not a key mediator in pathogenesis; systemic antihistamines are not recommended in standard AAO guidelines.
ICD-10 H10.05 drugs
Also known as: Viral conjunctivitis, Bacterial conjunctivitis
Drugs used for this condition
- DCarbomerAdd-on therapy · Artificial tear in gel form, polyacrylic polymerIn conjunctivitis carbomer gel is sometimes used to ease the soreness. It does not treat the infection – it contains no substance with pharmacological activity. In viral conjunctivitis a lubricating film eases the sensation while the illness clears on its own; in bacterial conjunctivitis the antibiotic decision belongs to a doctor. The ficha técnica warns about technique: the tube tip must not touch the eye or any surface, otherwise the gel is contaminated and becomes a source of infection itself. Examination is needed for pain, light sensitivity, reduced vision, injury or iris inflammation. If the gel was offered as conjunctivitis treatment instead of an examination, consider seeking a second opinion from an ophthalmologist.
- DHypromelloseAdd-on therapy · Artificial tear, ocular surface lubricantA red eye with discharge is often treated with an artificial tear simply because it is already at home. Hypromellose does not treat infection: it has no pharmacological action at all and only moistens the surface. In viral conjunctivitis that brings relief while the illness clears on its own in one to two weeks, but it does not speed recovery. In bacterial conjunctivitis the antibiotic decision belongs to a doctor, and the ficha técnica warns that other eye medicines are instilled 5 minutes before the artificial tear, otherwise the gel gets in their way. A doctor is needed for eye pain, light sensitivity, reduced vision, injury, and when symptoms last beyond a week. If an artificial tear was offered as conjunctivitis treatment instead of an examination, consider seeking a second opinion from an ophthalmologist.
Marketing claims without evidence base
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
- DCetirizineNot recommended · Second-generation antihistaminesCetirizine is a second-generation antihistamine taken by mouth for allergic rhinitis and urticaria, and it is sometimes suggested for infectious conjunctivitis. There is no proof of benefit for this use: infectious conjunctivitis comes from a virus or bacteria, and blocking histamine does nothing about the cause of the inflammation. Bacterial cases respond to topical antibiotics prescribed by a doctor, while viral cases usually clear on their own with eye hygiene and supportive care. The substance is harmless in this role, but do not use it in place of treatment with proven benefit, since that risks missing the care you actually need.
- DLoratadineNot recommended · Second-generation antihistaminesLoratadine is an oral antihistamine used for allergic rhinitis and hives. It is sometimes suggested for infectious conjunctivitis too, but no convincing benefit has been shown for this use: the inflammation in an infection comes from viruses or bacteria, not from the histamine response that loratadine acts on. What actually helps with infectious conjunctivitis targets the cause – eye hygiene and rinsing, and for bacterial cases topical antibacterial drops prescribed by a doctor. The substance itself is harmless in this role, but do not use it in place of treatment with proven benefit, or you may miss the care you need.
- FTetryzolineNot recommended · Topical ophthalmic sympathomimetic, decongestantA red eye with discharge gets «whitening» drops so that a person looks normal and goes to work. That is a dangerous move. Tetryzoline has no action on the pathogen and merely masks the sign by which the disease is noticed: the redness leaves, the infection stays. The AEMPS ficha técnica warns directly that redness is sometimes caused by serious eye disease, infection, a foreign body or a corneal chemical burn, and those need a doctor's attention. There is a separate danger for people with a narrow anterior chamber angle: vasoconstrictor drops dilate the pupil and can trigger an attack of angle-closure glaucoma – in which the eye is also red and painful. Eye pain, light sensitivity, reduced vision, purulent discharge and halos around lights call for examination the same day. If «whitening» drops were offered for a red eye with discharge, consider seeking a second opinion from an ophthalmologist.
How to read tiers A–F
Evidence tiers belong to the drug-indication pair, not to the drug as a whole: the same substance can be A for one condition and F for another.
- AStrong evidence – first or second line in international guidelines
- BRecommended in selected cases
- CStudy data contradict each other
- DBenefit not proven, no documented harm
- FDocumented harm, or risk without benefit