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Certain drugs can cause serious or occasionally life-threatening effects if consumed in combination with grapefruit or its juice.
Consuming grapefruit or its juice (fresh or frozen) can increase, or less commonly decrease, the effects of some drugs. There are several substances in grapefruit that interfere with the way your body handles certain drugs.
These effects are known to be caused by the combination of grapefruit and its juice with certain drugs and health products used in the treatment of medical conditions, including, but not limited to:
Sour oranges, such as Seville, or their juice, may have an effect similar to grapefruit juice. Most other citrus fruits, such as lemons, limes, citrons, naturally sweet oranges and tangerines are not thought to have this effect. However, tangellos, a hybrid of grapefruit, may also interfere with drugs.
There are substances in grapefruit that can interfere with the way your body absorbs and breaks down (metabolizes) certain drugs. This interference allows a higher amount of the drug than usual to circulate in your bloodstream, which can occasionally result in serious or life-threatening adverse reactions.
As little as one glass of grapefruit juice (8 oz. or 250 mL) can cause an increased blood drug level and the effects can last for three days or more. Therefore, even if you drink the juice in the morning and do not take your medication until bedtime, the level of the drug in your blood could still be affected.
The effects vary from one person to another, from one drug to another, and from one grapefruit juice preparation to another. This results in an unpredictable increase in blood drug level, which in some cases can cause serious effects.
Take the following precautions to minimize the risk of adverse effects when consuming grapefruit or its juice:
Health Canada has issued several communication documents to remind health care providers of possible interactions between grapefruit and drugs. In addition, Health Canada is working with the drug manufacturers whose products are adversely effected by grapefruit, to ensure that the needed information is placed on the product label. A public advisory has been issued on grapefruit and its effect on certain drugs.
Contact your doctor or pharmacist if you have any concerns about possible interaction between the drug you are taking and grapefruit.
To report all adverse reactions or drug interactions with grapefruit contact:
(All information below will be available in the Web version only)
Adverse reactions or drug interactions with grapefruit can also be reported to the following Regional ADR Centres:
Additional source of information for health care professionals: