Grapefruit can be bad for your health, especially if you mix a glass of juice with certain drugs, Health Canada says.

The agency warned Friday that substances in grapefruit interfere with the way your body reacts with some drugs, so that the effect is increased, or more rarely, decreased.

And it's not just grapefruit that can cause problems; sour orange juice, from Seville oranges, for example, and Tangelos, a hybrid grapefruit, can also cause problems.

But sweet oranges and other citrus fruits, such as lemons and limes, are not a problem.

Health Canada said the grapefruit problem is well-documented in medical literature, but the public may not be aware of it.