Common OTC drugs that carry serious health risks

By Naveed Saleh, MD, MS
Published March 9, 2021

Key Takeaways

Look around and you’ll notice a preponderance of over-the-counter drugs. They’re available at grocery stores, retail outlets, drug stores, and mass merchandisers. OTC drugs do provide great benefit to the average American, according to the Consumer Healthcare Products Association (CHPA).

“The availability of OTC medicine creates substantial value for the U.S. healthcare system, totaling approximately $146 billion in savings per year when compared to alternatives. OTC medicines also significantly increase access to treatment. On average, each dollar spent on OTC medicines saves the U.S. healthcare system approximately $7.20,” notes a CHPA research report.

But, for all the good they do, OTC medications also have a dark side. Here are dangerous adverse effects posed by five common OTC drugs.


Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) are a well-recognized cause of upper gastrointestinal (GI) bleeds—that is, bleeding that arises from the esophagus, stomach, or duodenum. They can also, however, cause lower GI bleeding—ie, from the small intestine (small bowel), which could be deadly. Small-bowel (SB) bleeding represents 5% of all GI bleeding and 80% of obscure bleeding presentations. In 30%-40% of cases of obscure GI bleeds, iron-deficiency anemia manifests. 

Of note, in Western countries, the most common cause of lower GI bleeds is angioectasia, while NSAID-induced small-bowel lesions are the major cause of small-bowel bleeding reported in studies from Eastern countries. 

In a study published in BMC Gastroenterology, researchers assessed the frequency of occurrence of NSAID-induced SB lesions in Korean patients with obscure GI bleeding, who had undergone capsule endoscopy—the gold standard for detecting obscure GI bleeds, which is performed after upper and lower endoscopy to identify cases of overt bleeding. Results from the study, which involved 83 patients, demonstrated a detection rate of small-bowel bleeding and lesions of 72.3% with capsule endoscopy. In total, 25 of 60 small-bowel bleeds were NSAID-induced.

As for a mechanism, the authors hypothesized, “NSAID-induced enteropathy is supposed to be mediated through COX inhibition. Administration of low-dose aspirin (an irreversible nonselective COX inhibitor) is also associated with SB [small-bowel] mucosal injuries; large erosions or ulcers were reported in 60% of healthy volunteers who took 100 mg of low-dose enteric-coated aspirin.”


Acetaminophen toxicity can manifest as liver failure and is the most common cause of liver transplantation in the United States. In the United States, it leads to 56,000 emergency department visits, 2,600 hospitalizations, and 500 deaths each year, with 50% representing unintentional overdoses. 

“Acetaminophen (N-acetyl-para-aminophenol, paracetamol, APAP) toxicity is common primarily because the medication is so readily available, and there is a perception that it is very safe. More than 60 million Americans consume acetaminophen on a weekly basis,” according to the authors of a review article. “Acetaminophen is used in many products in combination with other preparations, especially with opioids and diphenhydramine. Many people are not aware that it is contained in these combination medications.”


This OTC medication is used to relieve red, watery, irritated, itchy, eyes; sneezing; and runny nose induced by allergies, hay fever, or the common cold. It is also used to alleviate cough secondary to throat or airway irritation. It is formulated as tablets, capsules, dissolving strips, powder, and liquids taken by mouth. Diphenhydramine can be taken alone or with fever reducers, pain relievers, and decongestants. 

For the most part, adverse effects of diphenhydramine are limited to dryness, drowsiness, dizziness, nausea, and more. More serious side effects include vision problems and difficult/painful urination.


In rare instances, proton-pump inhibitors (PPIs) can induce serious adverse effects. In the United States, PPIs sold over the counter include lansoprazole, esomeprazole, and omeprazole magnesium; they are used for treating stomach and esophagus problems. PPIs are effective, but are tied to a gamut of side effects, including increased risk of osteoporosis, electrolyte imbalance, hip fractures, and vitamin B12 deficiency, as well as Salmonella, Campylobacter jejuni, and Clostridium difficile infections. Life-threatening adverse effects include Steven‐Johnson syndrome and toxic epidermal necrolysis.

Authors of a case report highlighted the co-occurrence of acute interstitial nephritis (AIN) and autoimmune hemolytic anemia (AIHA) in a previously healthy 43-year-old woman, which they ascribed to omeprazole.

“While PPI are often safe, they can cause serious complications such as AIN and AIHA,” they concluded. “Rarely, more than one PPI‐induced complication can simultaneously occur. Therefore, PPI should judiciously be prescribed. Early diagnosis of PPI‐induced adverse effects is essential to prompt discontinuation of PPI and initiation of supportive therapy to improve clinical outcomes.”


This OTC cough suppressant is found in more than 120 products marketed for cough and cold. It has become a popular drug of recreational misuse, and results in about 6,000 emergency room visits a year. Recreational users of dextromethorphan (DXM) take more than recommended doses to feel altered time perception, experience visual hallucination, and increase awareness. When mixed with alcohol, acetaminophen, or other OTC drugs, it can be toxic.

“Watch for warning signs of DXM abuse such as loss of interest in activities or hobbies, empty cough and cold medication containers, declining grades, and medicinal smells,” notes an article on the Poison Control website.

Other symptoms that could be related to DXM poisoning include loss of coordination, slurred speech, dizziness, hallucinations, and agitation, according to the site.   

To learn more about OTC drugs and specific medical conditions that don’t mix, click here

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