Some physicians are sounding alarms over the continued widespread use of certain older allergy medications, arguing that the risks outweigh any benefit. Tens of millions of adults and children routinely take diphenhydramine best recognized under the Benadryl brand whether to dull springtime hay fever or as a makeshift sleep aid because of its sedating effects.
For decades, diphenhydramine has been a familiar fixture on pharmacy shelves, promoted for quieting runny noses, itchy skin, watery eyes, and incessant sneezing. Its longstanding market presence has given it an aura of safety and harmlessness. Internal medicine specialists now challenge that perception and contend the U.S. Food and Drug Administration should reconsider whether such an older medication should remain over-the-counter.
What exactly is diphenhydramine?
Diphenhydramine is part of the first wave of antihistamines developed in the mid-20th century. These drugs are small and lipid-soluble, meaning they easily cross the blood–brain barrier. Once inside the central nervous system, they induce heavy drowsiness, slow reaction times, and dampen coordination.
Sedation may look mild on the surface, but it carries meaningful social and economic costs. Fatigue can drag down school performance, blunt workplace productivity, and significantly raise the likelihood of accidents. Driving studies have been especially damning: volunteers under the influence of diphenhydramine were more impaired than individuals who exceeded legal blood alcohol limits. That comparison tends to jolt clinicians, because it reframes the drug not as a sleepy allergy remedy but as a potential public safety issue.
Beyond fatigue lies a broader set of anticholinergic side effects: dry mouth, constipation, blurred vision, confusion, and difficulty passing urine. These symptoms are especially hazardous for older adults, who may already struggle with balance, cognition, and hydration. Geriatricians have warned for years that strong anticholinergic drugs can worsen delirium and contribute to falls or hospitalizations. Diphenhydramine has also been implicated in overdoses among adolescents, both experimental and accidental.
The neurological debate has only intensified as research has explored potential long-term impacts. Several observational studies have associated chronic use of strong anticholinergic drugs with increased risk of cognitive decline. While these studies cannot prove causation, the pattern has pushed many clinicians toward a precautionary stance.
Safer successors to Benadryl
Pharmaceutical development did not stop with the first generation. The late 20th century saw the arrival of second-generation antihistamines, including fexofenadine (Allegra) and loratadine (Claritin). These newer drugs are far less likely to cross into the brain, so they rarely sedate and can be taken during the workday without compromising alertness. They also last longer, often requiring just a single daily dose. Most allergists now consider them the appropriate first-line therapy for routine seasonal allergies.
The larger puzzle is why diphenhydramine retains cultural dominance despite less favorable safety profiles. Some clinicians cite consumer habit, brand familiarity, and the perception that older drugs are “tried and true.” Others point to market inertia: Benadryl is cheap, ubiquitous, and has spent decades being stocked in household medicine cabinets. Physicians pushing for reform argue that regulatory bodies should update labeling, shift it behind the counter, or at least improve public education so consumers understand the trade-offs.
The debate highlights how medical knowledge evolves while real-world behavior lags behind. It also illustrates the peculiar power of pharmacy shelves: once a drug becomes normalized as an everyday item, dismantling that status is far harder than inventing a better replacement.