What are the benefits and harms of antibiotics for acute bacterial conjunctivitis?

Key messages

Topical antibiotics may improve signs and symptoms as well as bacterial clearance in participants with acute bacterial conjunctivitis. However, some antibiotics can cause unwanted effects on the eyes or eyelids; no evidence suggests that antibiotics cause unwanted effects in other parts of the body.

What is acute bacterial conjunctivitis?

Acute bacterial conjunctivitis is a condition in which the thin layer over the white areas and the inside lining of the eyelids of one or both eyes becomes red and inflamed from a bacterial infection. Acute bacterial conjunctivitis is usually contagious and hence children and working adults are advised to avoid going to school or work when affected. Fortunately, it resolves spontaneously in most cases.

How is acute bacterial conjunctivitis treated?

People with acute bacterial conjunctivitis are often given treatment at the site of the infection, usually as antibiotic eye drops or ointment, to speed recovery. However, the benefits of antibiotics have been questioned when considering they can cause irritation or allergic reaction in and around the eyes or surrounding skin. 

What did we want to find out?

We examined whether antibiotics alone or in combination with steroid, can improve signs and symptoms of conjunctivitis or help clear the associated bacteria. We also evaluated whether antibiotics would result in undesirable effects on the eyes.

What did we do?

We performed a systematic review by searching for studies that compared antibiotics in eyedrop, ointment, or tablet form with inactive controls. We summarized these study findings and reported the results together with our level of confidence in them based on how studies were conducted.

What did we find?

We found that antibiotics likely increase clinical cure and microbiological cure after a course of treatment in comparison with placebo. Antibiotic use also is associated with fewer participants stopping their treatment earlier than they are supposed to. However, for some individuals, non-fluroquinolone but not fluoroquinolone antibiotics, may result in more unwanted effects on the eyes or eyelids than placebo though we were very uncertain about the relevant evidence. There was no evidence that antibiotics were associated with systemic side effects such as headache or altered sense of smell. 

What are the limitations of the evidence?

The current update focused on adults and children aged one month or older. Therefore, the evidence does not pertain to antibiotic treatment for neonatal conjunctivitis in neonates younger than one month old. We did not find studies that compared effects of the same antibiotics used in short versus long duration. Therefore, the current review was unable to suggest for or against the prescription duration for acute bacterial conjunctivitis.

How up-to-date is this evidence?

The evidence is up-to-date as of April 2022.

Authors' conclusions: 

The findings of this update suggest that the use of topical antibiotics is associated with a modestly improved chance of resolution in comparison to the use of placebo. Since no evidence of serious side effects was reported, use of antibiotics may therefore be considered to achieve better clinical and microbiologic efficacy than placebo. Increasing the proportion of participants with clinical cure or increasing the speed of recovery or both are important for individual return to work or school, allowing people to regain quality of life. Future studies may examine antiseptic treatments with topical antibiotics for reasons of cost and growing antibiotic resistance.


Read the full abstract...

Acute bacterial conjunctivitis is an infection of the conjunctiva and is one of the most common ocular disorders in primary care. Antibiotics are generally prescribed on the basis that they may speed recovery, reduce persistence, and prevent keratitis. However, many cases of acute bacterial conjunctivitis are self-limited, resolving without antibiotic therapy. This Cochrane Review was first published in The Cochrane Library in 1999, then updated in 2006, 2012, and 2022.


To assess the benefits and side effects 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 2022, Issue 5), MEDLINE (January 1950 to May 2022), Embase (January 1980 to May 2022), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases in May 2022.  

Selection criteria: 

We included randomized controlled trials (RCTs) in which any form of antibiotic treatment, with or without steroid, had been compared with placebo/vehicle in the management of acute bacterial conjunctivitis. This included topical and systemic antibiotic treatments.

Data collection and analysis: 

Two authors independently reviewed the titles and abstracts of identified studies. We assessed the full text of all potentially relevant studies and determined the included RCTs, which were further assessed for risk of bias using Cochrane methodology. We performed data extraction in a standardized manner and conducted random-effects meta-analyses using RevMan Web.

Main results: 

We included 21 eligible RCTs, 10 of which were newly identified in this update. A total of 8805 participants were randomized. All treatments were topical in the form of drops or ointment. The trials were heterogeneous in terms of their eligibility criteria, the nature of the intervention (antibiotic drug class, which included fluoroquinolones [FQs] and non-FQs; dosage frequency; duration of treatment), the outcomes assessed and the time points of assessment. We judged one trial to be of high risk of bias, four as low risk of bias, and the others as raising some concerns.

Based on intention-to-treat (ITT) population, antibiotics likely improved clinical cure (resolution of clinical symptoms or signs) by 26% (RR 1.26, 95% CI 1.09 to 1.46; 5 trials, 1474 participants; moderate certainty) as compared with placebo. Subgroup analysis showed no differences by antibiotic class (P = 0.67) or treatment duration (P = 0.60). In the placebo group, 55.5% (408/735) of participants had spontaneous clinical resolution by days 4 to 9 versus 68.2% (504/739) of participants treated with an antibiotic. Based on modified ITT population, in which participants were analyzed after randomization on the basis of positive microbiological culture, antibiotics likely increased microbiological cure (RR 1.53, 95% CI 1.34 to 1.74; 10 trials, 2827 participants) compared with placebo at the end of therapy; there were no subgroup differences by drug class (P = 0.60). No study evaluated the cost-effectiveness of antibiotic treatment. Patients receiving antibiotics had a lower risk of treatment incompletion than those in the placebo group (RR 0.64, 95% CI 0.52 to 0.78; 13 trials, 5573 participants; moderate certainty) and were 27% less likely to have persistent clinical infection (RR 0.73, 95% CI 0.65 to 0.81; 19 trials, 5280 participants; moderate certainty).

There was no evidence of serious systemic side effects reported in either the antibiotic or placebo group (very low certainty). When compared with placebo, FQs (RR 0.70, 95% CI 0.54 to 0.90) but not non-FQs (RR 4.05, 95% CI 1.36 to 12.00) may result in fewer participants with ocular side effects. However, the estimated effects were of very low certainty.