Antibiotics versus placebo for acute bacterial conjunctivitis

Acute bacterial conjunctivitis is an infective condition in which one or both eyes become red and inflamed. The condition is not normally serious and in most cases resolves spontaneously. People with acute conjunctivitis are often given antibiotics, usually as eye drops or ointment, to speed recovery. The benefits of antibiotics to the sufferer of conjunctivitis have been questioned. We found 11 randomised controlled trial (RCTs) from different parts of the world which recruited a total of 3673 participants overall. We judged two of the trials to be of high quality, and we graded the remainder as poor quality. This updated review provides clearer evidence that use of antibiotic eye drops can speed up the resolution of symptoms and infection, and that they are unlikely to be associated with any serious side effects.

Authors' conclusions: 

Although acute bacterial conjunctivitis is frequently self limiting, the findings from this updated systematic review suggest that the use of antibiotic eye drops is associated with modestly improved rates of clinical and microbiological remission in comparison to the use of placebo. Use of antibiotic eye drops should therefore be considered in order to speed the resolution of symptoms and infection.

Read the full abstract...

Acute bacterial conjunctivitis is an infection of the conjunctiva. Both the palpebral and the bulbar ocular conjunctival surfaces are usually affected and typically become red and inflamed. Antibiotic therapy is widely used for the treatment of acute bacterial conjunctivitis. This Cochrane Review was first published in The Cochrane Library in 1999; updated in 2006 and again in 2012.


To assess the benefits and harms of antibiotic therapy in the management of acute bacterial conjunctivitis.

Search strategy: 

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 7), MEDLINE (January 1950 to July 2012), EMBASE (January 1980 to July 2012), OpenGrey (System for Information on Grey Literature in Europe) (, the metaRegister of Controlled Trials (mRCT) (, ( and the WHO International Clinical Trials Registry Platform (ICTRP) ( We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 18 July 2012.

Selection criteria: 

We included double-masked randomised controlled trials (RCTs) in which any form of antibiotic treatment had been compared with placebo/vehicle in the management of acute bacterial conjunctivitis. This included topical, systemic and combination (for example, antibiotics and steroids) antibiotic treatments.

Data collection and analysis: 

Two authors (UN and SM) independently checked and reviewed the titles and abstracts of identified studies. We assessed the full text of all potentially relevant studies. We graded the included RCTs for methodological quality using Cochrane methodology. We performed data extraction in a standardised manner. We performed random-effects meta-analyses using RevMan.

Main results: 

We identified 11 eligible RCTs which randomised a total of 3673 participants. One further trial, which was published in abstract form in 1990 but has yet to be reported fully, is currently 'awaiting assessment'. Six of the 11 included studies have been included for the first time in this latest (2012) update. The trials were heterogeneous in terms of their inclusion and exclusion criteria, the nature of the intervention, and the outcome measures assessed. We judged two of the trials to be of high quality and graded the remainder as poor quality.

Meta-analyses of data on clinical and microbiological remission rates revealed that topical antibiotics were of benefit in improving 'early' (days two to five) clinical (risk ratio (RR) 1.36, 95% confidence interval (CI) 1.15 to 1.61) and microbiological (RR 1.55, 95% CI 1.37 to 1.76) remission rates. At the 'late' time point (days six to 10), antibiotics were found to still confer modest benefits in clinical remission (RR 1.21, 95% CI 1.10 to 1.33) and microbiological cure rates (RR 1.37, 95% CI 1.24 to 1.52). By days six to 10, 41% (95% CI 38 to 43) of cases had resolved in those receiving placebo. We found no data on the cost-effectiveness of antibiotics. No serious outcomes were reported in either the active or placebo arms of these trials, suggesting that important sight-threatening complications are an infrequent occurrence.