Your Health Checkup: Use Caution with Over-the-Counter Medications

Over-the-counter medications like pain relievers and antihistamines have many benefits, but like all treatments, OTCs are not without potential side effects, and users must be aware of possible negative consequences.

Photo of a Pharmacy aisle
(Mihai_Andritoiu /

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“Your Health Checkup” is our online column by Dr. Douglas Zipes, an internationally acclaimed cardiologist, professor, author, inventor, and authority on pacing and electrophysiology. Dr. Zipes is also a contributor to The Saturday Evening Post print magazine. Subscribe to receive thoughtful articles, new fiction, health and wellness advice, and gems from our archive. 

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I am one of millions of Americans who rely on over-the-counter (OTC) medications; that is, medications available without prescription used to self-treat a variety of conditions. Each U.S. household spends about $442 annually on OTC products, which are said to save $146 billion for the health care system each year by avoiding expensive medical alternatives.

OTC medications have many benefits. They offer easy access since they are distributed by a wide variety of outlets, such as grocery and drug stores. They also present users with inexpensive alternatives to safely and effectively treat many distinct categories of illness, including allergies, pain, fungal infections, red eye, cough/cold/flu illnesses, upper and lower gastrointestinal problems, skin afflictions, insomnia, and smoking cessation.

However, like all treatments, OTCs are not without potential side effects, and users must be aware of possible negative consequences. For example, pain relievers such as aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause bleeding, usually from the GI tract. As I’ve noted in the past, NSAIDs, particularly diclofenac (Voltaren) can increase the risk of cardiovascular complications such as heart attacks and strokes.

More than 60 million Americans consume acetaminophen weekly, which is often thought to be a safer alternative to pain treatment. It is frequently combined with other drugs such as opioids and diphenhydramine. Taken in large doses, acetaminophen can cause liver failure and is the most common cause of liver transplantation in the U.S., leads to 56,000 emergency department visits, 2,600 hospitalizations, and 500 deaths each year, with 50% from unintentional overdoses.

Diphenhydramine (Benadryl), an antihistamine, is often used to treat allergies that cause red, itchy eyes, cough from airway irritation, insomnia, and motion sickness. Multiple side effects include dry mouth, nose, and throat, drowsiness, dizziness, loss of appetite, and constipation. More serious side effects comprise vision problems and difficulty urinating or painful urination.

Omeprazole (Prilosec) belongs to a group of drugs known as proton pump inhibitors used to reduce the amount of stomach acid and relieve symptoms such as heart burn related to gastroesophageal reflux disease. Generally safe, they can cause a constellation of side effects such osteoporosis, electrolyte imbalance, hip fractures, and vitamin B12 deficiency, as well as diarrhea from infections due to Salmonella, Campylobacter jejuni, and Clostridium difficile. Rare life-threatening adverse effects include severe skin rashes, kidney inflammation, and anemia.

Dextromethorphan is a cough suppressant found in more than one hundred products sold to treat coughs and colds. Common side effects include blurred vision, difficulty urinating, drowsiness or dizziness, nausea or severe vomiting, shakiness and unsteady walk, slowed breathing, unusual excitement, nervousness, restlessness, or severe irritability. It may be misused in large doses for its mental side effects and results in about 6,000 emergency room visits a year. When mixed with alcohol, acetaminophen, or other OTC drugs, it can be toxic.

Loperamide (Imodium) is a synthetic opioid taken to relieve diarrhea (often, traveler’s diarrhea) by slowing the movement of the gut, which decreases the number of bowel movements and makes the stool less watery. It treats only symptoms and not the cause of the diarrhea. Side effects include dizziness, drowsiness, tiredness, or constipation.

This list is only a partial catalog of over 80 classes of OTC medications, each with its own set of side effects. Because they are available without a doctor’s prescription does not automatically make them safe, any more than dietary supplements labeled “natural” are necessarily safe. After all, a snake bite, a bee sting, and poison ivy are “natural.” So be sure to read accompanying materials that list side effects, take medications in the lowest dose that is effective and for the shortest time possible, and avoid combining with multiple other drugs.

Featured image: Mihai_Andritoiu /

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