Grapefruit and watermelon: why it is potentially dangerous to consume these fruits at the same time as medication ?

Pamplemousse, pastèque : des fruits potentiellement à risque

Vitaminés d’un côté, dangereux d’un autre… Stars des marchés estivaux, certains fruits renferment une double dace, façon Docteur Jekyll and M. Hyde… C’est notamment le cas du pamplemousse et encore de la pastèque, pour des raisons différentes. Explications.

St. John's wort, goldenseal, ginseng… if some plants can cause interactions with certain medications, this is also the case for a fruit like grapefruit. In other words, its consumption concomitantly with that of a medication is likely to cause adverse effects.

More serious adverse effects

This citrus fruit contains substances called furanocoumarins which inhibit intestinal enzymes… which are particularly involved in the metabolism of medications! As the French Medicines Agency recalled in 2012, “this is not a reduction in their effectiveness, but an increase in the frequency and severity of their adverse effects“.

Hypocholesterolemics, immunosuppressants

The number of molecules concerned would be limited. Cholesterol medications would thus be part of it in the same way as immunosuppressants – "to cite those with which the consequences can be severe" – and also anti-arrhythmics and antidepressants. On the other hand, "there are no interactions described with other citrus fruits (oranges, lemons) or apples", specified the French agency.

Advice ? If you are taking medication:

read the instructions carefully and ask your pharmacist if you have any questions; do not take your medication with a glass of grapefruit juice.

Watermelon and the kidneys

Another flagship summer food also contains some harmful effects, in certain circumstances: hyperkalemia, following the consumption of this fruit full of water. But also potassium which is said to be involved in the occurrence of this potentially fatal disorder likely to lead to kidney failure. Which means that the warning mainly concerns patients who suffer from chronic kidney failure. If you are concerned, ask your doctor or pharmacist.