It’s actually bad for the gut.

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You’ve probably heard that antibiotics kill all kinds of bacteria in your body (even the good types) and that taking probiotics can undo the negative effects the meds have on the gut. But a new study in the journal Cell found the opposite is true. 

When people took probiotics after a course of antibiotics in an effort to counterbalance the meds, their gut bacteria didn’t bounce back, even five months later. But when people gave their gut bacteria time to recover on its own without the supplement, it was restored within three weeks.
Ironically, taking probiotics after antibiotics keeps your gut from returning to normal. The supplements act as placeholders for natural bacteria, so your body takes longer to start producing it on its own again. 

That leads to a condition called gut dysbiosis: bacterial imbalances in the GI tract that can increase your risk of infection, explains study author Eran Elinav, MD, Ph.D., immunology chair at the Weizmann Institute of Science in Rehovot, Israel.
In this case, being passive about your gut health is the most proactive approach. After antibiotics, wait at least three weeks before taking probiotics again.