People taking prescription drugs may want to think twice before eating grapefruit. Researchers say the number of prescription drugs that have a negative interaction with grapefruit have more than doubled since 2008.

Analysts found more than 85 drugs that may have such a reaction; 43 can have serious side effects. Researchers say enzymes in the citrus fruits can deactivate roughly half of the effects of a medication. That can increase the amount of a drug that gets metabolized, which would be like taking many doses at once.