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Nutrition and daily life

Grapefruit — fruit card: the best-known food–drug interaction

Grapefruit looks like a healthy fruit, but it can change blood levels of dozens of medicines, including some used in leukemia. This card explains why grapefruit needs special care.

Last updated: ~2 min read
Pink grapefruits on a dark board.
Figure 1.Grapefruit: beautiful, but handle with care.

01Short answer

Grapefruit and its juice block the CYP3A4 enzyme in the gut and can raise blood levels of some medicines dangerously. This applies to some tyrosine kinase inhibitors, ciclosporin and tacrolimus, some statins and other drugs. The effect of one glass can last more than a day. During treatment, unless your doctor has said it is fine, avoid grapefruit, pomelo and bitter orange.

02Simple explanation

Grapefruit raises drug levels.

One glass is enough.

The effect lasts over a day.

Also pomelo and bitter orange.

03Scientific explanation

FDA: grapefruit juice blocks the CYP3A4 enzyme, so some medicines build up in the blood and side effects increase.

Furanocoumarins cause this effect; they are also in pomelo and bitter (Seville) orange.

WHO: at least 400 g of fruit and vegetables a day is recommended; during treatment the amount may vary with appetite and your doctor’s advice.

FDA: wash produce under running water before cutting or peeling, because a knife can carry germs from the skin into the flesh.

04What happens in the body?

Which medicines?

Some tyrosine kinase inhibitors, immunosuppressants (ciclosporin, tacrolimus), some statins, and heart and blood pressure medicines. Check your list with a pharmacist.

Grapefruit in shadow on the left, a pill organiser on the right.
Figure 2.Grapefruit and medicines.

What to have instead

Sweet orange, apple and pear usually have no such effect (see “Orange — fruit card: vitamin C and some caution”, “Apple — fruit card: from Guba orchards to the table”).

An orange and an apple in front, grapefruit behind.
Figure 3.Swap for sweet orange and apple.

Washing and peeling

Wash your hands, rub the fruit under running water, dry it with a clean towel, then peel or cut it. Soap or bleach solutions are not needed.

Cut fruit

Keep cut fruit in the fridge and eat it within 1 day; do not leave it at room temperature for more than 2 hours.

05Fruit: four steps

Whole fruit, swap bruised, wash and peel, eat cut fruit soon.

Whole fruit — No spots.1Whole fruitNo spots.
Not bruised — Fresh and whole.2Not bruisedFresh and whole.
Wash and peel — Running water.3Wash and peelRunning water.
Eat soon — Fridge, 1 day.4Eat soonFridge, 1 day.
VitaminsA natural source.
FibreFor the gut.
SafetyWashing.

06Key points at a glance

TopicIn brief
Which medicines?Some tyrosine kinase inhibitors, immunosuppressants (ciclosporin, tacrolimus), some statins, and heart and blood pressure medicines. Check your list with a pharmacist.
What to have insteadSweet orange, apple and pear usually have no such effect (see “Orange — fruit card: vitamin C and some caution”, “Apple — fruit card: from Guba orchards to the table”).
Washing and peelingWash your hands, rub the fruit under running water, dry it with a clean towel, then peel or cut it. Soap or bleach solutions are not needed.
Cut fruitKeep cut fruit in the fridge and eat it within 1 day; do not leave it at room temperature for more than 2 hours.

07Key terms

CYP3A4
An enzyme that breaks down medicines.
Tyrosine kinase inhibitor
A targeted drug used in some leukemias.
Neutropenia
Low neutrophils, raising infection risk.
Potassium
A mineral for the heart and muscles.
Fibre
The part of plants that helps the gut work.

08Key points

  • Avoid grapefruit unless allowed.
  • Pomelo and bitter orange too.
  • Check your medicine list.
  • Wash under running water.
  • Eat cut fruit soon.

09Frequently asked questions

What if I eat one segment?

Even a little can have an effect; tell your doctor, especially on targeted drugs.

What if I take my medicine in the morning and grapefruit at night?

No; the effect is long-lasting, so spacing does not help.

Does this fruit treat leukemia?

No. It is a pleasant part of eating, not a treatment.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. What if I eat one segment?

  2. What if I take my medicine in the morning and grapefruit at night?

  3. Does this fruit treat leukemia?

My questions

12Sources

  1. U.S. FDA. Grapefruit Juice and Some Drugs Don’t Mix
  2. Leukemia & Lymphoma Society. Diet Guidelines for Immunosuppressed Patients
  3. U.S. FDA. Selecting and Serving Produce Safely
  4. NHS. 5 A Day: what counts?
  5. National Cancer Institute. Eating Hints: Before, During, and After Cancer Treatment
  6. USDA. FoodData Central
  7. NIH Office of Dietary Supplements. Vitamin D Fact Sheet
  8. MedlinePlus (U.S. National Library of Medicine). Nutrition
  9. NHS. Vitamins and minerals
  10. MedlinePlus (U.S. National Library of Medicine). Ferritin Blood Test
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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