What the Healthy Tennis Player Should Know about Drug Interactions
Young Ju, Ph.D.
A 2021 Centers for Disease Control and Prevention (CDC) survey reported that approximately 64.8% of adults (ages 18 or over) in the U.S. had taken a prescription medication in the previous 30 days. The percentage was higher among women than men (70.9% vs. 58.4%) and increased with age. Among prescription-drug users, 49.8% took at least one prescription medication, 24.7% used three or more, and 13.5% used five or more (1). Prescription medications are used to treat and/or prevent many health conditions; however, sometimes drug interactions occur and cause potential adverse effects.
Drug Interactions
Drug interactions refer to reactions affecting how a drug acts in the body, which may change a drug’s efficacy and safety by altering its pharmacokinetics (how the body processes the drug from absorption to excretion) and pharmacodynamics (how the drug exerts its effect in the body) (2). Drug interactions could lead to reduced effectiveness, increased drug action, and increased toxicities.
There are several types of drug interactions: (3, 4, 5)
Drug-drug interaction: a reaction between two or more drugs or over-the-counter drugs. For example, many cold medications and allergy medications contain similar active ingredients. Taking two of these simultaneously could lead to an overdose, causing side effects like drowsiness, dizziness, or more serious complications.
Drug-supplement interaction: a reaction between a drug and a dietary supplement. For example, calcium can interfere with the absorption of certain antibiotics (e.g., tetracycline and fluoroquinolones) by forming insoluble complexes with these antibiotics in the intestine resulting in reduced effectiveness.
Drug-food interaction: a reaction between a drug and a food/beverage. For example, grapefruit can inhibit enzymes that break down statins (a class of cholesterol-lowering medications), leading to increased levels of statins in the blood.
Drug-condition interaction: a reaction between a drug and certain medical conditions. For example, when an individual with glaucoma takes antihistamines (e.g., Benadryl), pressure inside the eye could be elevated, potentially exacerbating that condition.
Drug interaction information is gathered through experimental methods and data collection and monitoring (3, 4).
Experiments are conducted in controlled settings, including cell studies, animal studies, human studies, and computational modeling (by analyzing existing data and known interactions).
Data are obtained and analyzed from actual cases reported by patients or healthcare professionals, from specialized databases tracking adverse events, from potential interactions, and from patient-reporting systems.
Managing Drug Interactions
Checking reported interactions and tracking your use of prescriptions, over-the-counter medications, and dietary supplements are the keys to managing drug interactions.
There are several sites [e.g., Drugs.com (https://www.drugs.com/); Medscape Interaction Checker (https://reference.medscape.com/drug-interactionchecker)] you can use to check for interactions between medications, herbals, vitamins, and alcohol.
The Office of Dietary Supplements has a useful tracking form called My Dietary Supplement and Medicine Record (https://ods.od.nih.gov/pubs/DietarySupplementandMedicineRecord.pdf?utm_medium=email&utm_source=govdelivery). It is an easy-to-use form that helps track dietary supplements and prescription and over-the-counter medications, including dosages, instructions, and who recommended them. You can also share this form with your doctors, pharmacists, and caregivers, helping ensure accurate communication and safe care.
Summary
Most adults can expect to need prescription drugs during their lifetimes. Drug interactions can lead to serious health problems. Before starting any new prescriptions, over-the-counter medications, or dietary supplements, always read the drug labels carefully, follow prescription instructions, ask your doctor or pharmacist about possible interactions, and keep track of all medications.
Dr. Young Ju is a Ph.D and Associate Professor of Human Nutrition, Foods, and Exercise at Virginia Tech.
References
Center for Disease Control and Prevention. “QuickStats: Percentage of Adults Aged ≥18 Years Who Took Prescription Medication During the Past 12 Months, by Sex and Age Group — National Health Interview Survey, United States, 2021” https://www.cdc.gov/mmwr/volumes/72/wr/mm7216a7.htm
Corrie and Hardman. “Mechanisms of drug interactions: pharmacodynamics and pharmacokinetics” Anesthesia & Intensive Care Med. 2022, 12(4):156.
U.S. Food and Drug Administration. “Drug Interactions: What you should know” https://www.fda.gov/drugs/resources-drugs/drug-interactions-what-you-should-know
Hammoud and Shapiro. “Drug interactions: What are important drug interactions for the most commonly used medications in preventive cardiology?” Med. Clinics North America 2022, 106(2):389.
National Institute of Health. “HIV treatment”https://hivinfo.nih.gov/understanding-hiv/fact-sheets/what-drug-interaction
This information is provided for your reference and you use at your own risk; you should rely on your medical professional for medical advice.
