Overuse and misuse of antibiotics may leave you drug resistant, vulnerable to infection and can also hamper cancer treatment, a study has found. Any negative impact of antibiotics on cancer treatment appears to go back to the gut and to whether the microbiota is needed to help activate the T cells driving treatment response, according to researchers. “It likely depends on what types of therapy physicians are giving to patients and how often they also are giving them antibiotics,” said Gang Zhou from the Augusta University in the US. Infections are typically the biggest complication of chemotherapy, and antibiotics are commonly prescribed to prevent and treat them, according to the study published in the journal Oncotarget. “We give a lot of medications to prevent infections,” said Locke Bryan from the Augusta University. “White blood cell counts can go so low that you have no defense against bacteria, and that overwhelming infection can be lethal,” said Bryan. In this high-stakes arena, where chemotherapy is increasingly packaged with newer immunotherapies, the researchers found more evidence that antibiotics’ impact on the microbiota can mean that T cells, key players of the immune response, are less effective and some therapies might be too.