How Prescription Drugs Interact Against Each Other, Food, Alcohol, Supplements, and Your Body

By Alan G. Bayham, RPh, MAOM, AVP, Medical Affairs, Ochsner Health Plan

Are you aware that some prescribed medications do not work well with others? In fact, there are many over-the-counter medications and supplements that might negate the effectiveness of prescribed drugs. Even some food and drink like fruit juices, diary products and green leafy vegetables might have a negative impact on the drugs that were prescribed by your physician to treat your medical condition. In fact, grapefruit and its juice alone can interact with more than 80 different medicines

The following are the 5 most common types of drug interactions:

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  1. A drug-drug interaction is when a medication reacts with one or more other medications. Sedatives or drugs to help you to sleep may their depression side effect on your central nervous system or respiration augmented by cough medicine.
  2. A drug-food/drink interaction is when something you eat or drank affects the impact of a medication. In fact, it can be dangerous to drink alcohol while taking certain medications. In addition, some vitamins and dietary supplements also interact negatively with various medications.
  3. A drug-lab test interaction – many prescription and over-the-counter drugs, as well as dietary supplements, can affect lab test results. This is important, because most medical decisions made in the United States are based on results from lab tests. For example, in 2020, the FDA issued a warning that biotin, often found in dietary supplements, can cause clinically significant incorrect results on lab tests. The FDA was particularly concerned because biotin can cause falsely low results, leading to missed diagnoses and potentially serious clinical implications. Also known as vitamin B7, biotin is found in vitamins and dietary supplements. Many supplements promoted for hair, skin, and nail growth contain biotin levels up to 650 times the recommended daily intake.
  4. Drug-Disease interactions – Drugs can also have different adverse side effects based upon different chronic diseases. For example, most salt substitutes should be avoided for patients with chronic renal disease because many contain large amounts of potassium. A little later in this article. I describe another such example involving a heart patient and an emergency room visit.
  5. Drug-Age Interactions – It’s no secret that when we get older, our body doesn’t work the way it used to. And that’s true for how we react to medicine. Our digestive system might not absorb medications as quickly. Liver problems might mean the drug builds up in the bloodstream or doesn’t get into it as fast as it should. And kidney trouble could affect how well medicine moves out of our body as waste.
    • Prescription drug use by older adults can often result in adverse drug events that contribute to hospitalization, increased duration of illness, nursing home placement, falls and fracture.
    • Because older adults are more likely to take multiple medications for multiple conditions, they are at higher risk of potentially harmful drug-disease interactions.
    • Many older adults also access care across multiple health care providers, so there is an increased risk of harmful drug interactions due to lack of communication and coordination between providers.
    • Furthermore, older adults are more likely to use medications long term, increasing their risk of physical and mental harm.

Here are 4 simple guidelines that will help you to minimize harmful drug effects when taking prescription medications:

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  1. Never change your drug regimen abruptly and without first talking to your health care provider.
  2. Bring a list of your medications, vitamins, supplements, and over the counter (OTC) medications with you when you meet with your physicians. Better yet, “brown bag” everything you take by and bring it all on your next visit to your primary care provider. Then, ask your provider to manually add these to the list of drugs they have for you in the electronic medical record.
  3. Try to fill your prescription at the same pharmacy each time. Your pharmacist is the health care specialist when it comes to being trained on drugs.
  4. Always read the medication fact sheet provided by your pharmacist with your prescription and do not throw it away. It will tell you how to take your medication and will let you know of possible side effects, restrictions, and what to do if you miss a dose. It may also inform you about other medications, over-the-counter drugs, food, vitamins, and supplements that might have a negative interaction.

Most health insurances, like Ochsner Health Plan, use a Pharmacy Benefits Manager (PBM) that checks every prescription filled at participating pharmacies and automatically alerts the pharmacists if they detect a potential interaction between the prescription being filled and one that you may already be taking.

  • One real-life example that I recall is when a patient had to go to an emergency room out of state and get an antibiotic. Naturally, when people have an emergency, they sometimes forget to mention all the other illnesses they have and drugs that they are taking. In this case, the ER physician prescribed a widely used antibiotic that was appropriate for most patients. However, one of the side effects of this particular antibiotic was that it could cause a decrease in heart rate.
    • When the patient went to the 24-hour pharmacy, the pharmacy submitted the antibiotic prescription to the PBM that was on the patient’s health plan card. The PBM automatically checked the patients drug records and noted that the patient was taking another prescription drug that was used most commonly for people with problems with irregular heart rates.
    • The pharmacist was instantaneously alerted to this potential drug interaction prior to filling the antibiotic. The pharmacist called the ER physician and told him about the potentially serious drug interaction.
    • The ER physician then told the pharmacist to cancel the first prescription and gave him a verbal prescription for a different antibiotic that did not have this interaction with the patient’s heart medication. All while the patient was still at the pharmacy.
    • The next day, I received a personal phone call from the ER physician thanking me and the PBM for alerting him to the drug interaction. It seems that while the patient was in the emergency room, the patient forgot to tell the triage nurse that he was taking a heart drug for his heart rate.

The advantage of an integrated health care delivery system is that physicians, pharmacists, and the insurance company all have access to the same electronic medical records system.

If you have questions about your prescription medication and potential side effects/interactions, please contact your health care provider or pharmacist.

Alan G. Bayham, RPh, MAOM has almost 50 years of pharmacy experience (47 years as a licensed, registered pharmacist in the state of Louisiana). His vast pharmacy experience includes retail, hospital, drug research, long-term care, and managed care.


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