A widely used allergy medication, diphenhydramine—best known by the brand name Benadryl—is facing new scrutiny from health experts, who now argue that its risks outweigh its usefulness, particularly when safer alternatives are available. In a recent review published by leading allergy specialists from Johns Hopkins University and the University of California, San Diego, calls have intensified for this first-generation antihistamine to be pulled from over-the-counter (OTC) and prescription markets in the United States, igniting worldwide interest and concern, including in Thailand where similar medications are popular.
Diphenhydramine has long been a household staple, reaching for everything from seasonal allergies and insect bites to sleep aid and cold symptoms. It became available in 1946 and has since been widely sold, especially in the US where more than 1.5 million prescriptions are written each year, in addition to countless OTC purchases. In Thailand, diphenhydramine-based products are also easily found at pharmacies and frequently used by families to relieve allergy symptoms or aid sleep, echoing patterns seen in American households (CNN).
For Thai readers, the recent warnings from US experts should raise awareness about the potential dangers of relying on diphenhydramine. According to the new review and expert interviews reported by CNN, the drug poses “disproportionate risks, especially for children and older adults,” compared to newer, second-generation antihistamines like loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra). Dr. Anna Wolfson, an allergist at Massachusetts General Hospital, highlighted incidents in her clinic where patients attempted to use diphenhydramine for acute allergic reactions to foods, when international guidelines recommend immediate use of epinephrine instead. “It’s time to move on,” said Dr. Wolfson. “For every single indication that people are using diphenhydramine, there are better drugs that are more effective at treating the symptoms people are trying to treat with fewer side effects.”
Part of the concern centers on diphenhydramine’s “first-generation” status as an antihistamine. The medication works by blocking H1 receptors—the body’s way of responding to allergens that trigger sneezing, itching, and runny nose. But this older drug doesn’t just act on those receptors. It enters the brain more readily, causing sedation and what experts refer to as cognitive impairment. Patients can become drowsy, miss warning signs of a severe allergic reaction, and experience impaired driving or functioning in daily life. In older adults, diphenhydramine can remain in the system for up to 18 hours, increasing the risks of falls, confusion, and disorientation (American Pharmacists Association). There are also growing concerns about a possible association with dementia, as cited by the review authors.
Children, however, may face even steeper risks. Diphenhydramine is linked to paradoxical reactions in some pediatric patients—including agitation, extreme sedation, and, in rare instances, coma or even death. Several fatalities have been attributed to overdose or misuse, especially with viral internet challenges like the so-called “Benadryl Challenge” on TikTok. Dr. Manuela Murray, director of general pediatrics and urgent care at the University of Texas Medical Branch, emphasized: “It should always be used under the guidance of a Medical Professional, and it is only indicated to treat allergic reactions and motion sickness.” She added that the medicine is ineffective for cold symptoms and inappropriate as a sleep aid for children, often leading to the opposite effect—hyperactivity.
Dr. Alyssa Kuban, a pediatrician and associate medical director at Texas Children’s Pediatrics, observed frequent misuse of diphenhydramine to treat cold and upper respiratory symptoms in children. She advocates for cetirizine as a safer, longer-lasting alternative that is less likely to cause sedation and should be the first-line choice for hives, seasonal allergies, or itchy rashes in young patients. Both Dr. Kuban and Dr. Murray recommend loratadine and cetirizine for children over six months old, with saline drops and suctioning preferred for infants.
The Consumer Healthcare Products Association, which represents the OTC medicine industry, acknowledges the side effects but maintains that “when used as directed, these medicines provide well-established therapeutic benefits for common health ailments,” urging consumers to follow drug labels and consult with healthcare providers if they have concerns (CHPA). Benadryl’s manufacturer, Kenvue, echoes this recommendation, stating that “responsible use is essential.”
Nonetheless, the expert panel behind the February review penned a strong recommendation: “It is time to say a final goodbye to diphenhydramine, a public health hazard.” They suggested moving products containing this ingredient behind pharmacy counters, paralleling regulatory models for pseudoephedrine. This would allow pharmacists to guide customers toward safer alternatives. The American Pharmacists Association also advises caution with products that combine diphenhydramine with cough and cold medicines—these combinations are exceedingly common in both US and Thai markets.
Thai health professionals may find additional cause for reflection in the Thai context. Over-the-counter access to diphenhydramine-based products is widespread, especially in smaller pharmacies and rural clinics where regulatory oversight can be patchy. A pharmacy faculty member from a prominent Bangkok university noted that diphenhydramine is still commonly dispensed, sometimes even for sleep problems or travel sickness. “Many families still believe in its effectiveness because they have used it for decades,” the academic explained, “but new evidence and international guidance show that we must be more careful, especially with vulnerable groups like children and the elderly.”
Thailand’s Drug Act does allow for periodic reviews of over-the-counter drug safety and efficacy. However, implementation can vary widely. In recent years, the Ministry of Public Health has updated guidance on certain cold medicines and promoted public awareness about the dangers of inappropriate self-medication, but there has not yet been a major move to restrict diphenhydramine. Some public hospitals have already switched to safer alternatives on their formularies, particularly for pediatric and geriatric care.
The cultural context also plays a role. Many Thai families rely heavily on local pharmacies as their first point of healthcare access, and there is longstanding trust in the advice of community pharmacists. On the one hand, this offers an opportunity for tailored guidance and safer use, but on the other, it raises challenges in keeping knowledge up-to-date with international standards. In Buddhist-majority Thailand, the concept of “do no harm” (ไม่ทำร้าย) is deeply embedded in healthcare, and increasing public awareness about evolving drug safety evidence aligns with these core values.
In the broader global context, concerns raised in the US often travel quickly to other markets through regulatory, academic, and media channels. Australia, for example, issued stronger warnings about first-generation antihistamines years ago, and the European Medicines Agency has recommended caution with sedating antihistamines, especially for younger children and older adults (EMA guidance). Such international trends provide a useful mirror for Thailand to review its practices.
Looking forward, public health authorities and professional organizations in Thailand may wish to consider the following actions: reevaluating the status of diphenhydramine as an over-the-counter drug, issuing updated guidance to pharmacists and clinicians, launching public information campaigns, and encouraging patients to use newer, safer antihistamines whenever appropriate. Policymakers could also draw on lessons learned from successful regulatory updates on other common OTC medications.
For Thai consumers, the practical advice is clear: Before reaching for familiar allergy or cold medicines, check the active ingredient. If it says “diphenhydramine” or a Thai-language equivalent (ดีเฟนไฮดรามีน), reconsider—especially if you are providing it to children, elderly relatives, or if you have a history of side effects. Ask your pharmacist or doctor about newer alternatives like loratadine, cetirizine, or fexofenadine, which offer similar or superior relief with fewer adverse effects. For suspected severe food allergies, remember that epinephrine, not an oral antihistamine, is the recommended emergency treatment—do not rely on diphenhydramine for life-threatening reactions.
As expert consensus grows around the world, Thailand has an opportunity to strengthen its medication safety standards and preserve the public’s trust with evidence-based guidance. Hospitals, pharmacists, and public health officials all play a vital role in communicating the message: tradition is not always synonymous with safety in modern medicine.
For those seeking more detailed information, the US review referenced in this article can be found summarized via Yahoo News/CNN. For Thai-specific advice, consult local pharmacists with up-to-date training, visit Ministry of Public Health communications, or follow updates from academic institutions.