Doctors in India were left puzzled when a 46-year-old man arrived at a hospital in Tamil Nadu with a painful, prolonged erection lasting more than five hours. The man had taken sildenafil, commonly known as Viagra, within the prescribed dose. What surprised doctors was that he had also consumed a large glass of pomegranate juice shortly before, which appeared to have intensified the drug’s effects. He was eventually treated with an injection to counter the reaction and advised to avoid the juice in the future.
This unusual case highlights a growing area of medical research: the complex and sometimes unpredictable ways that food interacts with medications. For decades, anecdotal reports and isolated case studies have pointed to foods altering how drugs behave in the body. Now, scientists are investigating these interactions more systematically, hoping not only to prevent dangerous side effects but also to potentially use certain foods to make treatments more effective.
Some food-drug interactions are already well known. Grapefruit, for instance, has been shown to amplify the potency of many common medicines, from cholesterol-lowering statins to blood pressure drugs and even anti-malarial treatments. The fruit blocks an enzyme known as cytochrome P450 3A4, which normally helps break down drugs in the body. Without this process, medications can remain in the bloodstream longer and at higher concentrations, sometimes leading to toxic effects.
Other foods have the opposite effect. High-fibre diets, for example, can reduce how well certain drugs are absorbed, weakening their impact. Meanwhile, cranberries were once thought to dangerously boost the blood-thinning effects of warfarin, though large-scale studies have since cast doubt on that link, with some health agencies continuing to advise caution.
Regulators have tried to address the issue by requiring pharmaceutical companies to test how new drugs behave when taken with food. Both the US Food and Drug Administration and the European Medicines Agency mandate trials where participants take drugs after fasting and after eating a standardised high-fat meal. Still, experts caution that such testing cannot cover every possible food-drug combination.
“It’s like a little factory,” said Jelena Milešević, a researcher at the Center of Research Excellence in Nutrition and Metabolism in Serbia. “You have a lot of inputs and a lot of outputs. Once all the chemical reactions of the body, of the food, and of the drug are meshed together, it’s huge, and it’s very difficult to separate.”
Researchers believe understanding these interactions more thoroughly could open new opportunities in medicine. Instead of merely avoiding harmful combinations, food could one day be used to improve how drugs work, allowing doctors to enhance treatments without raising doses. As Patrick Chan, professor of pharmacy practice at Western University of Health Sciences in California, noted: “Most drugs are unaffected by food. In the certain cases where they are, those are the ones we need to watch out for.”
