Weight Gain from Antibiotic Treatment: Not Just in Animals!

Use of antibiotics such as chlortetracycline — even in subtherapeutic doses — promotes growth in livestock through increased food intake and weight gain. This effect is explained by alterations of the animals' gut microbiome and contributes to the abundant use of antibiotics in factory farming. Previous uncontrolled studies have suggested that weight gain secondary to antibiotic treatment also occurs in humans; now, researchers in France have investigated the issue more systematically.

The researchers followed 48 patients who received long-term therapy with doxycycline (100 mg twice daily) and hydroxychloroquine (600 mg daily) for treatment of Q fever endocarditis between 2008 and 2011. Thirty-four individuals consulting in an outpatient uni…