Side Effects Can Be Serious. Because other blood vessels relax with these medications as well, increased blood levels of these drugs caused by grapefruit can decrease blood pressure (8). It can also affect the absorption of other drugs including itraconazole, an antifungal, antibiotic and quinidine. With most drugs that interact with grapefruit juice, “the juice lets more of the drug enter the blood,” Huang says. When I ran out of grapefruit, I was shocked to see the readings climb again. 1 Grapefruit is known to affect blood pressure and cholesterol drugs but the list of drugs has increased over time. Side Effects of Blood Pressure Medications. So now I need to go get more grapefruit. High blood pressure is a common health problem that can be treated with drugs and medications. Drinking grapefruit juice while taking some medications for high blood pressure might cause your blood pressure to go too low. Further research revealed that the grapefruit juice itself was actually increasing the amount of the study drug in the body. When this happens, the amounts of medication in your body can build up and cause serious side effects. However, (and this is a big however) consuming grapefruit while taking certain blood pressure medications can cause problems. Here are examples of some types of drugs that grapefruit juice can cause problems with (interact): Some statin drugs to lower cholesterol, such as Zocor (simvastatin) and Lipitor (atorvastatin). Moreover, prostate enlargement medications such as tamsulosin can also cause increased dizziness and low blood pressure when taken with grapefruit (19). Grapefruit seed extract can potentially have very serious side effects on your cardiovascular system. Elevated blood levels of this drug can worsen side effects and lead to infections, altered blood cell counts, lowered appetite, nausea, vomiting, diarrhea, hair loss, and fatigue, among others. Having grapefruit juice considerably increases buspirone concentrations. In addition, grapefruits contain pectin, which is a fiber that also helps lower blood pressure, and also contain certain other compounds that help reduce artery hardening. The first two are channel blockers, while the other two work to counteract angiotensin effects. However, it also is used for treating irregular heartbeat patterns. Generic name (Brand name) Medications that have little or no interaction with grapefruit juice. In some cases, not getting enough potassium can cause your blood pressure to rise, so eating grapefruit may help you lower your blood pressure. This includes calcium channel blockers, which are often prescribed for the treatment of hypertension. Grapefruit contains chemicals that can interfere with the enzymes that your body uses to break down certain medications. Grapefruit might increase how much cyclosporine (Neoral, Sandimmune) the body absorbs. As little as one glass of grapefruit juice (8 oz. Quinidine is an anti-malaria drug. These are typically prescribed to treat high blood pressure and angina. Interactions with grapefruit can occur with common and important medications - such as those that lower cholesterol, treat high blood pressure, or even those that fight cancer. Blood Pressure Medications. The ones that do are based on felodipine, nifedipine, losartan, and eplerenone. Quinidine is an anti-malaria drug. Some drugs that treat high blood pressure, such as Procardia and Adalat CC (both nifedipine). Side effects can vary based on the interacting drug and possible side effects. “When there is too much drug in the blood, you may have more side effects.” (Other statins such as fluvastatin (Lescol), pravastatin (Pravachol), and rosuvastatin (Crestor) have little or no interaction with grapefruit juice.) Side effects can range from abnormal heart rhythms, stomach bleeding, muscle pain, muscle breakdown, kidney damage, low blood pressure, difficulty breathing, sedation, and dizziness.