Clinically, taking a tablet of lovastatin with a glass of grapefruit juice is equivalent to taking 12 ~ L5 tablets of lovastatin with a glass of water, which will lead to muscle pain and even kidney disease. Some patients may have dizziness, palpitation, arrhythmia, etc. if they eat grapefruit or drink grapefruit juice during taking the antiallergic drug Terfenadine, and in severe cases, they may die suddenly. Grapefruit contains some active ingredients, which inhibit the metabolism and decomposition of statins in the body, and may even cause the accumulation of drugs in the body and even poisoning. Other drugs that have side effects on grapefruit are cyclosporine, caffeine, calcium antagonists and cisapride. Drinking a glass of grapefruit juice will last for 24 hours. Therefore, patients taking medicine, especially the elderly, had better not eat grapefruit or drink grapefruit juice. Avoid eating grapefruit 3 days before taking the medicine and 6 hours after taking the medicine.

Women taking birth control pills should avoid eating. Studies have shown that grapefruit has the most prominent influence on contraceptives. Experts say, "If a woman who takes birth control pills eats 1 ~ 2 grapefruit after sex, or takes birth control pills directly with a large glass of grapefruit juice, then she may become a mother, because grapefruit hinders women's absorption of birth control pills."

Grapefruit is cold, and people who have diarrhea due to spleen deficiency will have diarrhea after eating grapefruit. Therefore, people with deficiency and cold should not eat more.

There is also a saying that you can't eat with high-protein things. For example: milk, beef and mutton.