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On many prescription labels you will see a warning against consuming grapefruit whilst taking that medication. This has been a hot topic for many years now, and the list of medicines that are affected by grapefruit has grown. What many pharmacies or medical personnel don’t tell you is how and why grapefruit can be dangerous when mixed with certain medicines.
Grapefruit and Your Digestive System
There are special enzymes present in your small intestinal wall that enable medicines to be absorbed into the body, but grapefruit can block these enzymes or even destroy the medication. This results in less amounts of the medicine entering the body, but higher levels occurring in the bloodstream. This increase can enhance side effects of these medicines.
Drugs Affected By Grapefruit
The following list of drugs is the ones most commonly affected by the consumption of grapefruit. If you are unsure, or for some reason you cannot avoid taking grapefruit, discuss with your doctor the potential impact of eating or drinking grapefruit and any medicines you may be taking.
Cholesterol Drugs (statins) – atorvastatin, lovastatin, Lipitor, Zocor, simvastatin, vytorin.
Calcium Channel Blockers (for high blood pressure) – felodipine, nimodipine, nicardipine, nisoldipine, verapamil
Antihistamines – fexofenadine
Intestinal medicines – cisapride
Psychiatric drugs – triazolam, buspirone, tegretol, diazepam, midazolam, sertraline
Pain drugs – methadone
Antiarrhythmics – disopyramide, amiodarone
Immune suppressants – tacrolimus, cyclosporine
Impotence drugs – Viagra
HIV drugs - saquinavirsa
Other drugs that can be affected by grapefruit include:
- Tadalafil (Cialis)
There are potentially more drugs affected by grapefruit than are mentioned here, so if you are on any medication, it is essential you check with your health professional if it is okay to have grapefruit or not.
Timing of Medication and Grapefruit
Many people think that if they just don’t take the medicine at the same time as the grapefruit, the interaction won’t occur, but this is not the case. It may lower the severity of the interaction, but this is not always the case. The enzymes in the wall of the small intestine can stay blocked for more than 24 hours after eating grapefruit flesh or juice. This caution also applies to any medications that are only taken once a day. These are usually slow release drugs, and will still be affected by the consumption of grapefruit.