Understand How Your Medications Interact

By Joy Darnell, Director of the Shell Point Pharmacy

Communication and knowledge are critical components to the success of any medication. Often, people don’t carefully read the labels on their prescription bottles, and it can cause serious problems. Some combinations of medications can have serious and potentially toxic effects, so it’s important to understand how medications interact with each other.

Most medication interactions are mediated by enzymes found mainly in the liver. The enzymes are responsible for breaking down drugs and helping to eliminate them from the body. Some medications, such as Tegretal and Dilantin, may increase the enzymes and cause a decrease in the amount of another drug in the body, thus reducing the drug’s effectiveness. Other medications, such as Cipro and Tagamet, can decrease the enzymes and cause an increase in the amount of another drug in the body, thus creating over medication.

Over-the-counter products can also affect the way medications work in the body. For example, decongestants can cause an increased heart rate. Antacids and other gastrointestinal medications can decrease the absorption of medications and should only be used short term. Anti-inflammatory drugs can affect blood pressure and increase water retention and present possible gastrointestinal side effects. Aspirin has both gastrointestinal side effects and can cause increased bleeding, so its use should be considered only after discussing it with the doctor and pharmacist.

Multivitamins are generally safe with most medications. However, the verdict is still out on Vitamin E, which can cause increased bleeding. Taking Vitamin E should be discussed with the doctor or pharmacist to effectively manage the medication plan.

Another consideration is the use of herbal products. Echinacea, garlic supplements, ginseng, ginkgo biloba, glucosamine, kava, saw palmetto, selenium, and St. John’s Wart provide many benefits. However, both the doctor and pharmacist need to know which supplements are being taken to help prevent negative side effects. For instance, St. John’s Wart should not be used in combination with other anti-depressants; and, ginseng can increase blood pressure and reduce the efficiency of other medications.

Even certain liquids can create complications with medications. Studies have shown that grapefruit juice decreases the amount of metabolizing enzymes which can lead to increased levels of certain drugs in the body. Some of these drugs include blood pressure medications such as Procardia, cholesterol lowering agents such as Zocor, and sleep aids such as Halcion. Since interaction varies from person to person, and from drug to drug, it is best to avoid drinking grapefruit juice with certain medications.

Key points to keeping medications straight include using pill organizers, knowing exactly what medications are prescribed, knowing when to take them, and understanding what foods to avoid. Most side effects result because medications are not taken as directed. It is essential that doctors and pharmacists have a complete picture of what medications are being taken, so be sure to take a complete list of vitamins and medications to your next visit with your doctor.