Does Grapefruit Affect My Medicine?


       Grapefruit has been known for its high content of vitamin C and much higher vitamin A as compared to orange, making it one of the popular healthy juices and supplements. We know taking medicine with plain water is safe but how about when we drink juices or have slices of grapefruit together? In short, having grapefruit in diets while taking certain medicines does affect the medicine effectiveness.

      Down to the question of what medicine is affected by grapefruit? 85 drugs cause some possible interactions and 43 drugs resulting in serious adverse effects. That’s surely a long list of medicine-phew. Fret not, we’ll be going through some of the popular prescriptions.

    But first, how do grapefruit affect medicine? Grapefruit juice leads to more drugs being taken into the blood and increases the amount of the medicine staying in the bloodstream, thus making the body susceptible to more side effects. The fruit has the ability to disrupt drug metabolism by blocking an enzyme called CYP3A4 in the small intestine, leading to high volume of drugs stagnant in the blood.

       Statin drugs such as simvastatin and atorvastatin consumed to lower cholesterol does interact with grapefruits. Reported cases of rhabdomyolysis in patients with simvastatin eating 1 whole grapefruit for 2 weeks and another patient with atorvastatin drinking 1- 2 glasses of fresh grapefruit juices for 5 days has been recorded. Rhabdomyolysis is a condition where the body breaks down body muscle tissues into the blood causing blood toxicity. This can cause serious injury to the heart and kidney and death when severe.

   Nifedipine, an antihypertensive drug has been also known to interact with grapefruit by causing side effects such as hypotension. Hypotension or low blood pressure which seem harmless is actually dangerous as it causes a person to feel dizzy and light-headed, some may lose consciousness and balance. Patients can easily fall and get into horrendous accidents throughout their daily life.

    Antibiotics such as erythromycin widely used in infectious diseases in upper respiratory tract, skin and soft tissues, as well as alternative for those with history of allergy to penicillin, do pose a big threat for torsades de pointes when combined with grapefruit. Torsades de pointes caused by the abnormal heart rhythm. In serious cases it can lead to sudden cardiac arrest or even death. Patients will feel the heart beating faster than normal even they are at rest or sensation of light-headed and faint

    Sildenafil or what is known publicly as Viagra, loved by man all around the world for generations, also interacts with grapefruit. Grapefruit will cause higher levels of the drug in blood. Although this condition could be beneficial for those with erectile dysfunction, it can trigger headaches and low blood pressure.

          Estrogens therapy commonly known for post menopause woman, need to be careful in introducing grapefruit in their daily diet. Studies shown women going for estrogens therapy and consuming a quarter of grapefruit or more per day are in greater risk of breast cancer. This is due to the long availability of the estrogens in the body system.

   With over 85 possible drug interactions that may cause severe side effects, it is quite impossible for patients to know or remember which medicine should or should not be taken with grapefruit. The rule of thumb is that every time you are given a prescription by a doctor, ask directly if it is really safe to have it with any liquid aside from plain water, especially fruit juices. You can also go through the leaflets or pamphlets attached inside the box of the medicine.  Consult your doctor for more information on drug interactions. Know our Hajj Vaccination package.