These common OTC medications do more harm than good

By Naveed Saleh, MD, MS
Published March 22, 2021

Key Takeaways

The vast majority of healthy adults who use over-the-counter (OTC) medications are at low risk for any associated health risks. But young children, older adults, and those taking more than one type of medication are at increased risk of adverse effects caused by certain OTC medications.

People with asthma, blood dyscrasia, diabetes, epilepsy, gout, liver disease, and heart disease are also predisposed to greater risk. And because these drugs are so common, some of their dangerous side effects are highly unanticipated by those affected by them.

Here are five examples of dangerous adverse effects that physicians should be aware of.

Omeprazole and kidney problems

The use of omeprazole and other proton-pump inhibitors (PPIs)—used to treat acid reflux and ulcers—has been linked to chronic kidney disease (CKD). According to the results of a retrospective study published in PLOS ONE, in 199 patients with CKD, 70.6% of patients who used omeprazole experienced CKD progression versus 10.5% of non-users. Moreover, there was a higher risk of progression to more severe disease in those using omeprazole. 

The authors noted that renal damage induced by PPI use may be caused by “the deposition of the drug and its metabolites in renal tissue, which may culminate in renal interstitial fibrosis, leading to chronicity of the lesion and onset of CKD; reduced nitric oxide synthesis, caused by inhibition of the proton pump of cell lysosomes, and thus production of highly reactive superoxide anion, which causes renal endothelial dysfunction; and hypomagnesemia, as low magnesium levels are able to increase secretion of atherogenic and inflammatory substances, producing endothelial dysfunction of the renal tissue.”

Nasal sprays and anosmia

The essential mineral zinc is either naturally present or added to foods and available as a dietary supplement. It is also present in cold lozenges and available in OTC cold remedies.

Cases of anosmia stemming from the use of zinc-containing gels or sprays prompted the NIH to issue a warning. “In June 2009, the FDA warned consumers to stop using three zinc-containing intranasal products because they might cause anosmia. The manufacturer recalled these products from the marketplace. Currently, these safety concerns have not been found to be associated with cold lozenges containing zinc,” the NIH wrote.

Aspirin and Reye syndrome

Reye syndrome is a potentially deadly but rare childhood illness marked by acute noninflammatory encephalopathy with fatty liver failure. After its discovery by Australian pathologist R.D.K. Reye in 1963, the United States started surveilling the complication in the early 1970s, which subsequently led to strict warnings on the use of aspirin in children in the 1980s. Following such widespread warnings, aspirin use dropped in children.

This syndrome often starts while convalescing from a viral illness following aspirin intake. Although less than 0.1% of children who take aspirin develop Reye syndrome, more than 80% of children diagnosed with this condition have taken aspirin in the previous 3 weeks. It initially presents as vomiting and confusion with rapid progression to coma and death.

According to the authors of a review published in StatPearls, “The exact pathophysiology of Reye syndrome is not precisely known; however, it appears to involve mitochondrial injury in the setting of a viral illness. Aspirin may cause or perpetuate damage to cellular mitochondria resulting in inhibition of fatty-acid metabolism. The neurologic features of Reye syndrome likely result from hepatic mitochondrial dysfunction causing elevated ammonia levels.”

They added, “Hyperammonemia may induce astrocyte edema resulting in diffuse cerebral edema and subsequent elevated intracranial pressure. Pathology studies have revealed astrocyte edema, loss of neurons, fatty degeneration of kidneys, and a swollen and a reduced number of mitochondria.”

Notably, the treatment of Reye syndrome is supportive with close monitoring in the ICU. The patient may require hemodynamic support via central venous access, airway intubation, placement of a Foley catheter to check urine output, liver biopsy, and intracranial pressure monitoring.

Acetaminophen and skin reactions

Acetaminophen is found in many over-the-counter and prescription drugs used to treat pain and reduce fever. Rarely, the ingestion of acetaminophen can result in serious skin reactions, including Stevens-Johnson Syndrome, toxic epidermal necrolysis, and acute generalized exanthematous pustulosis. These conditions can be lethal.

According to the FDA, “Reddening of the skin, rash, blisters, and detachment of the upper surface of the skin can occur with the use of drug products that contain acetaminophen. These reactions can occur with first-time use of acetaminophen or at any time while it is being taken. Other drugs used to treat fever and pain/body aches (eg, nonsteroidal anti-inflammatory drugs, or NSAIDS, such as ibuprofen and naproxen) also carry the risk of causing serious skin reactions, which is already described in the warnings section of their drug labels.”

Antihistamines and hallucinations

In the midst of WWII, the most popular antihistamine—diphenhydramine—was first synthesized in 1943. By 1950, antihistamine use became widespread, accompanied by a rise in antihistamine toxicity. Of note, antihistamine toxicity is caused by anticholinergic effects, not by competitive H1-receptor binding and sedation.

High levels of H1 antihistamines such as diphenhydramine can lead to hallucinations and a host of other unwanted anticholinergic adverse effects brought to mind by a mnemonic you likely learned in medical school: “red as a beet, dry as a bone, hot as a hare, blind as a bat, mad as a hatter, and full as a flask.” Respectively, this translates to vasodilation of the skin, anhidrosis, hyperthermia due to decreased sweat production, mydriasis leading to blurred vision, hallucinations and delirium, and urinary retention induced by decreased detrusor contraction. Other effects of diphenhydramine include the potentiation of opioid receptors, modulation of serotonin function, and heightened levels of dopamine. 

To learn more about other side effects caused by these and other OTC medications, click here. Further, physicians should be aware that there are certain OTC drugs that don’t mix well with certain medical conditions, including glaucoma, enlarged prostate, ulcers, and more. 

Share with emailShare to FacebookShare to LinkedInShare to Twitter