HealthDay News — In cases of lower-respiratory-tract infection when pneumonia is not suspected, amoxicillin provides little symptomatic benefit, study findings indicate.

Paul Little, MD, from the University of Southampton in the United Kingdom, and colleagues randomly assigned adult patients with acute lower-respiratory-tract infections (cough of ≤28 days’ duration), in whom pneumonia was not suspected, to receive either amoxicillin (1 g three times daily for seven days; 1,038 patients) or placebo (1,023 patients). Results were published in Lancet Infectious Diseases.

The researchers observed no significant difference between the groups with respect to the duration of symptoms rated “moderately bad” or worse (hazard ratio, 1.06; P=0.229) or mean symptom severity score (1.69 with placebo vs. 1.62 with amoxicillin; P=0.074).

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In the amoxicillin group, new or worsening symptoms were significantly less common than in the placebo group (15.9% vs. 19.3%; P=0.043; number needed to treat, 30). In the amoxicillin group, nausea, rash and diarrhea were significantly more common than in the placebo group (number needed to harm, 21; P=0.025). There was no evidence of selective benefit in patients aged 60 years or older (595 patients).

“In conclusion, amoxicillin provides little symptomatic benefit for patients presenting in primary care who are judged to have clinically uncomplicated lower-respiratory-tract infections,” the researchers wrote. “Any mild, short-term benefits of antibiotic treatment should be balanced against the risks of side-effects and, in the long term, of fostering resistance.”


  1. Little P et al. Lancet Infect Dis. 2012; doi:10.1016/S0140-6736(08)61345-8.