Combining grapefruit with prescription medication has become much more dangerous. A new study shows that over the past four years, the number of drugs that produce serious side effects—including gastrointestinal bleeding, kidney damage, breathing problems, irregular heartbeat, and sudden death—when taken even the night before eating the fruit or drinking its juice has increased from 17 to 43. Those drugs include common prescriptions for blood pressure, cholesterol-lowering statins, pain and cancer medications, and some antibiotics. More than 40 additional drugs also interact with grapefruit, with lesser side effects. “Taking one tablet with a glass of grapefruit juice is like taking five tablets with water,’’ study author David Bailey, a pharmacologist at the Lawson Health Research Institute in Ontario, tells Researchers have known for 20 years that chemicals in grapefruit called furanocoumarins block the ability of the small intestine and the liver to break down these drugs, causing them to stay in the body longer at higher levels and potentially leading to overdoses. Experts say even a little grapefruit juice can be dangerous.