Grapefruit juice or grapefruits themselves can be healthy snacks. According to the Mayo Clinic, grapefruits contain nutrients, such as vitamin C, potassium and lycopene. Although thought to be safe, grapefruits can interact with certain medications. The chemicals in grapefruit juice and pulp can interfere with drug breakdown in the digestive system. Unfortunately, this can lead to increased amounts of the drug in the bloodstream. A few medications should be avoided when eating grapefruit.
Fexofenadine belongs to a set of drugs called antihistamines. It interferes with histamine, a substance in the body that causes sneezing, nasal congestion, itchy eyes and a runny nose. Specifically, fexofenadine treats seasonal allergies and hives.
Fexofenadine's side effects include diarrhea, stomach pain, nausea, a headache and drowsiness. Back or muscle pain, fatigue and menstrual cramps are additional fexofenadine side effects, according to Drugs.com.
Fexofenadine's absorption can be decreased when taking antacid medications and drinking fruit juices, such as apple, orange or grapefruit juice, according to Drugs.com. Antacids must be taken 15 minutes before or after taking fexofenadine for the same reason.
Fexofenadine may interact with such medications as ketoconazole or erythromycin. Its effect may be decreased or the aforementioned side effects may occur.
Amiodarone may not be effective in treating heart rhythm abnormalities when taken with grapefruit. This drug is an anti-arrhythmic medication that works to normalize an irregular or fast heart rate. Drugs.com says that amiodarone should only be used in people suffering from a potentially life-threatening heart rhythm problem.
Amiodarone's side effects include nausea, strange skin sensations, a headache, vomiting, a poor appetite, a headache and dry eyes. Flushing of the face, constipation, decreased sex drive (libido), fatigue, trouble sleeping and a poor appetite are amiodarone's other effects. Sometimes amiodarone may cause chest pain, nervousness, dizziness, wheezing and a worsened heartbeat.
Combining amiodarone with such drugs as flecainide, ketoconazole, cimetidine, pimozide, quinolones, macrolide antibiotics, ziprasidone or serotonin receptor antagonists can lead to further heart problems and seizures.
Amiodarone can severely affect appearance and cause your skin to turn blue or gray--especially on the hands and face. Also, amiodarone can harm a baby during pregnancy and breastfeeding.
Buspirone is a medication used to treat anxiety. Unfortunately, eating a grapefruit while taking buspirone can decrease its effectiveness. MedlinePlus says that buspirone's side effects include vomiting, constipation, trouble breathing, fatigue, nervousness, weakness, numbness, dry mouth and stomach problems. Buspirone also causes light-headedness, dizziness, depression and excitement. In some instances, buspirone causes itching, a skin rash, blurry vision and a fast or irregular heartbeat.
Carbamazepine, phenobarbital, ketoconazole, itraconazole and verapamil are just some of the drugs that interact with buspirone to cause the previously mentioned side effects or decrease buspirone's effectiveness.