I categorically accept that bacteria differ from viruses; so antibiotics DON'T help in viral infections. I also read this and this; so no need to explain this. I've read about the negative effects (eg exacerbation of antibiotic resistance); I ask only about the positive effects here, and NOT for reasons to exploit antibiotics for infections not due bacteria.

Yet I myself have witnessed that some people with viral infections feel better after wrongly taking antibiotics? and so asked about this first on Cognitive Sciences SE.

Initially, I suspected only some placebo effect, but this enlightened me on the side benefits of antibiotic consumption for a viral infection and motivated this question, now that my original question on psychology has revealed the relevance of biology.


1 Answer 1


There are indeed antibiotics which have immunomodulatory side-effects, these are mostly from the class of macrolide antibiotics (erythromycin, clarithromycin, roxithromycin, azithromycin) and to some degree from the tetracyclines. Beta-lactam antibiotics (as Penicillin or Ampicillin) have not been shown to be immunomodulatory, but they are among the most commonly used. See reference 1 for more details.

The biggest effect has been shown on pulmonary diseases such as cystic fibrosis or diffuse panbrochiolitis (see reference 2).

Although the exact mechanism of action is not known, Macrolides are know to downregulate the inflammatory cascade and that the reduce the strong cytokine expression of some viral infections. However, these regulatory effects are relatively weak if you compare them to the anti-inflammatory properties of corticosteroids. So the question here is if the advantages are really sufficient compared to the problems, which an unnecessary use of antibiotics may cause. See reference 3 and the references in the paper for more details here.

Antibiotics may be useful to fight bacterial secondary or superinfections which accompany a virus infection.


  1. Immunomodulatory Properties of Antibiotics
  2. Macrolide activities beyond their antimicrobial effects: macrolides in diffuse panbronchiolitis and cystic fibrosis
  3. Macrolide Therapy in Respiratory Viral Infections

You must log in to answer this question.