Because cancer patients take numerous medications, they face an increased risk for potentially serious drug interactions—but chemotherapy agents aren’t the main cause. Medications for other conditions or drugs to manage side effects are more likely to be involved, according to a report in the Journal of the National Cancer Institute. Researchers asked more than 400 adult patients about the medicines they took, reviewed their medical charts and used a software program and pharmacology textbooks to identify potential drug interactions. The team found that 27 percent of patients were at risk for at least one of 276 potential drug interactions, with more than three-quarters of those severe enough to require medical treatment if they occurred. Nearly 10 percent of the potential drug interactions could cause permanent damage or be life threatening. To protect yourself against harmful drug interactions, be sure to keep an updated list of your medicines to show each of your doctors and have a single pharmacy fill all prescriptions.