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Is Benadryl Bad For You?

Also Known As: antihistamine



Short answer

Benadryl, while effective for allergic reactions and as a short-term sleep aid, poses certain risks. Short-term use can lead to drowsiness, dry mouth, dizziness, among other effects. Long-term use is linked to cognitive decline, sleep quality disruption, and increased tolerance. There are safer alternatives for those concerned about these side effects.



Long answer

Understanding Benadryl: Uses and Mechanism of Action

Benadryl, with the active ingredient diphenhydramine, is a widely used medication known primarily for its ability to counteract symptoms of allergies. This includes relief from itching, hives, and nasal congestion. It is also commonly used as a sleep aid due to its sedative properties. However, the understanding of Benadryl’s effects and usage extends beyond these common applications, providing valuable insights into its mechanism of action within the body.

Diphenhydramine, the active component of Benadryl, belongs to a class of medications known as first-generation antihistamines. Antihistamines are substances that block the action of histamine, a compound in the body that plays a key role in allergic reactions. Histamine is responsible for symptoms such as sneezing, itching, and increased mucus production. By inhibiting the action of histamine, Benadryl effectively reduces these symptoms.

The sedative effect of Benadryl, which contributes to its use as a sleep aid, stems from its ability to cross the blood-brain barrier. Once in the brain, it inhibits the activity of acetylcholine, a neurotransmitter associated with wakefulness. This action contributes to drowsiness, making it easier for individuals to fall asleep.

Understanding the dual action of Benadryl—as both an antihistamine and a sedative—highlights its versatility as a medication. However, it also underscores the importance of using it responsibly, particularly due to the potential side effects associated with its sedative properties. Use in allergy relief and as a short-term sleep aid must be balanced against these considerations, with users advised to follow dosage instructions carefully.

Research and expert opinion support the effectiveness of diphenhydramine in treating allergy symptoms and aiding in sleep. However, it is recommended for short-term use only, due to risks associated with long-term use, such as cognitive decline in the elderly. A study published in the Journal of the American Medical Association (JAMA) highlighted the potential link between long-term use of anticholinergic drugs, like Benadryl, and an increased risk of dementia.

In summary, Benadryl’s role in managing allergy symptoms and aiding sleep is well-established, owing to its mechanism of blocking histamine and inhibiting acetylcholine. However, responsible use, guided by an understanding of its effects and potential side effects, is crucial for maximizing its benefits while minimizing risks.

Short-Term Side Effects of Benadryl Use

Diphenhydramine, known by its common brand name Benadryl, is an over-the-counter antihistamine widely used for the relief of allergies and as a sleep aid. While Benadryl is effective and generally safe when used as directed, it's important to be aware of the potential short-term side effects associated with its use. The severity and occurrence of these side effects can vary based on individual factors such as age, dosage, and overall health condition.

Common Short-Term Side Effects

  • Drowsiness: Diphenhydramine is known for its sedative properties, making drowsiness one of the most common side effects. This can impact your ability to drive or operate machinery safely.
  • Dry Mouth: Benadryl can decrease saliva production, leading to a sensation of dryness in the mouth.
  • Dizziness: Users may experience dizziness, impacting balance and coordination.
  • Nausea and Vomiting: Some people might experience gastrointestinal discomfort, including nausea and vomiting, particularly at higher doses.
  • Constipation: Reduced gut motility may lead to constipation, a common issue with antihistamine use.
  • Blurred Vision: Temporary changes in vision may occur, usually manifesting as blurriness.
  • Confusion: Especially in older adults, confusion or delirium may be a notable side effect.

While these side effects are generally not severe and often diminish as your body adjusts to the medication, it is crucial to take them seriously, especially if they persist or worsen. For example, a study published in the Journal of the American Medical Association highlighted concerns regarding anticholinergic drugs like Benadryl and their association with temporary cognitive impairment in older adults. The American Academy of Family Physicians also advises caution when using antihistamines in elderly patients due to the increased risk of dizziness, confusion, and falls.

Understanding these potential short-term side effects can help users make informed choices about their health and safety when considering Benadryl for allergy relief or as a sleep aid. Always consult with a healthcare provider if you have concerns about these side effects or if the symptoms persist, as this may indicate a need for an adjusted dose or an alternative treatment approach.

Long-Term Risks Associated with Chronic Benadryl Use

Chronic use of Benadryl (diphenhydramine), a commonly used antihistamine for allergy relief, sleep aid, and symptom relief of the common cold, poses several long-term health risks. Understanding these risks is crucial for those who rely on Benadryl for prolonged periods. This section delves into the potential long-term effects, supported by scientific studies and expert analysis.

Firstly, it's essential to understand that diphenhydramine, the active compound in Benadryl, can cross the blood-brain barrier, affecting the central nervous system. This attribute underlies many of the drug's therapeutic effects but also contributes to its risk profile when used long-term.

Cognitive Decline: A significant concern associated with chronic Benadryl use is its potential to impair cognitive function. Research, including a study published in JAMA Internal Medicine, has linked long-term use of anticholinergic drugs like Benadryl to an increased risk of dementia. The study suggests that continuous use over three years can significantly increase the risk.

Sleep Quality Disruption: Although Benadryl is often used as a sleep aid due to its sedative properties, long-term use can adversely affect sleep architecture. This can lead to a decrease in sleep quality, altering the natural stages of sleep and reducing REM sleep. Over time, this can exacerbate sleep-related problems, contradicting the desired effect.

Increase in Tolerance: With prolonged use, individuals may develop tolerance to Benadryl's effects, necessitating higher doses to achieve the same therapeutic effects. This escalation can amplify the risk of adverse effects and potential toxicity.

Anticholinergic Syndrome: Chronic intake of Benadryl can lead to anticholinergic syndrome, characterized by dry mouth, blurred vision, constipation, urinary retention, and in severe cases, tachycardia and confusion. These symptoms result from the drug's inhibition of the neurotransmitter acetylcholine in the body.

Heart Problems: Long-term Benadryl use has been associated with an increased risk of heart problems. Anticholinergic effects can influence heart rate and potentially contribute to arrhythmias and palpitations, especially in those with underlying heart conditions.

In conclusion, while Benadryl can offer significant relief for allergy sufferers and those with short-term sleep disturbances, its chronic use is linked to several adverse health risks. It is essential for users to weigh these risks against the benefits and consider alternatives or lifestyle adjustments to mitigate long-term health implications. Consulting healthcare professionals and considering non-pharmacological approaches for allergy relief and sleep management are advisable steps for those concerned about the long-term use of Benadryl.

Link Between Benadryl and Cognitive Function

The connection between Benadryl (diphenhydramine) and cognitive function has become an area of increasing interest and concern among both healthcare professionals and the general public. Benadryl, a widely-used over-the-counter antihistamine for treating allergic reactions, cold symptoms, and insomnia, has been scrutinized for its potential impact on cognitive health, particularly with long-term use.

Research has indicated that diphenhydramine, the active ingredient in Benadryl, belongs to a class of medications known as anticholinergics. These drugs block the action of acetylcholine, a neurotransmitter in the brain involved in learning, memory, and muscle activation. Blocking acetylcholine can lead to side effects related to cognitive function, such as confusion, memory impairment, and decreased alertness, especially in older adults.

Several studies have highlighted the cognitive risks associated with anticholinergic drugs like Benadryl:

  • A study published in the Journal of the American Medical Association (JAMA) Internal Medicine in 2015 found that higher cumulative use of anticholinergic drugs was associated with an increased risk of developing dementia, including Alzheimer's disease.
  • Research in the British Medical Journal (BMJ) in 2014 noted that anticholinergic medication use was linked with cognitive decline and increased risk of dementia in a population-based study involving older adults.
  • Further, a study in Age and Ageing in 2016 suggested that anticholinergic drug exposure, particularly through medications like Benadryl, was associated with poorer cognitive performance and decreased brain volume in middle-aged participants, emphasizing the potential impact even in individuals under the age of 65.

However, it's important to note that while these studies suggest a correlation between long-term Benadryl use and cognitive impairment, they do not prove causation. Moreover, most of the research focuses on older adults and those with pre-existing cognitive dysfunction, raising questions about the generalizability of these findings to the broader population.

Given the potential risks, experts recommend caution with the long-term use of Benadryl, especially in older adults or individuals at risk for cognitive decline. Alternatives with a lower anticholinergic burden may be considered for those needing long-term treatment for allergies or insomnia. Consultation with a healthcare provider is crucial for anyone concerned about the impact of medication on cognitive health.

In conclusion, while Benadryl is effective for the temporary relief of allergic symptoms and occasional insomnia, awareness of its possible link to cognitive impairment is important. Ongoing research into the mechanisms by which anticholinergic medications affect cognitive function and whether these effects are reversible will be key in understanding how best to use these medications while minimizing risks to cognitive health.

Benadryl's Role in Drowsy Driving and Accident Risk

Diphenhydramine, the active ingredient in Benadryl, is an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. These symptoms may include rash, itching, watery eyes, itchy eyes/nose/throat, cough, runny nose, and sneezing. While effective for these purposes, diphenhydramine is also known for its sedative properties, which can significantly impair cognitive and motor functions. This facet of Benadryl's pharmacologic profile raises concerns about its role in drowsy driving and the associated accident risk.

According to research, the sedating effects of diphenhydramine can make driving or operating machinery dangerous, as reaction times and decision-making capabilities can be considerably impaired. The U.S. Food and Drug Administration (FDA) has issued warnings regarding the use of antihistamines like Benadryl, stating that they can lead to drowsiness and may impact an individual's ability to perform tasks requiring alertness, such as driving.

A study published in the Journal of Allergy and Clinical Immunology highlighted that individuals taking diphenhydramine were significantly more impaired in driving performance than those who did not take the drug, equating the impairment level to a blood alcohol concentration that exceeds legal limits in many jurisdictions. This impairment can lead to slow reaction times, decreased coordination, diminished focus, and ultimately, an increased risk of accidents.

Understanding the magnitude of the risk, it is crucial to consider the statistics related to drowsy driving. The National Highway Traffic Safety Administration (NHTSA) reports that drowsy driving is responsible for more than 6,000 fatal crashes annually in the United States. While not all these cases are directly linked to the use of diphenhydramine or similar medications, the potential for these drugs to contribute to such accidents is a serious concern.

Experts advise that individuals taking Benadryl or any medication containing diphenhydramine should not drive or operate heavy machinery. If the use of such medication is necessary, it is recommended to arrange alternative transportation or adjust schedules to avoid activities requiring high levels of concentration and motor coordination while the drug is active in the system.

For those requiring allergy or cold relief but needing to maintain alertness, non-sedating antihistamines are available as alternatives to diphenhydramine. These drugs can offer symptom relief without significantly impairing cognitive functions and are a safer option for individuals who must drive or perform tasks requiring sharp focus.

In summary, while Benadryl is an effective treatment for various allergic reactions and symptoms, its sedating effects pose a notable risk for drowsy driving and related accidents. Understanding this risk and taking appropriate precautions can help mitigate the potential for harm, ensuring both the safety of the individual taking the medication and others on the road.

Alternatives to Benadryl for Allergy and Sleep Aid

While Benadryl is a commonly used antihistamine for alleviating symptoms of allergies and occasionally as a sleep aid, concerns about its side effects and risks, particularly in long-term use, have led individuals to seek safer alternatives. Below, we explore various options that can be considered both for allergy relief and as sleep aids, focusing on effectiveness and safety profiles.

Alternative Antihistamines for Allergies:

  • Loratadine (Claritin): A non-drowsy antihistamine that does not cross the blood-brain barrier as readily as Benadryl, decreasing the risk of sedation. Effective for daily use in managing symptoms of seasonal allergies.
  • Cetirizine (Zyrtec): Another non-sedating antihistamine, though some users may experience mild drowsiness. Offers long-lasting allergy relief and is beneficial for chronic urticaria (hives).
  • Fexofenadine (Allegra): Known for its non-drowsy formula, it's suitable for those who need allergy relief without the sedative effects. Also, it's less likely to interact with other medications.

Nasal Sprays and Eye Drops:

  • Fluticasone (Flonase): A steroid nasal spray that can reduce inflammation and symptoms of allergic rhinitis with fewer systemic effects than oral antihistamines.
  • Azelastine (Astelin): A prescription antihistamine nasal spray offering quick relief from nasal symptoms with minimal drowsiness.
  • Ketotifen (Zaditor): An over-the-counter antihistamine eye drop, effective for itchy, watery eyes due to allergies without the systemic side effects of oral medications.

Alternatives for Sleep Aid:

  • Melatonin: A hormone that regulates the sleep-wake cycle. Supplementing with melatonin can help adjust the body's internal clock, particularly useful for jet lag or irregular sleep patterns.
  • Valerian Root: An herbal supplement with mild sedative effects, often used to improve sleep quality and ease insomnia. However, more research is needed to fully understand its efficacy and safety.
  • Lavender: Inhaling lavender scent or using lavender oil in a diffuser can promote relaxation and potentially improve sleep quality, with minimal risk of side effects.

It's essential to consult with a healthcare provider before making changes to your allergy or sleep aid regimen, especially if you have existing health conditions or are taking other medications. This ensures that the alternative selected is safe and appropriate for your specific needs. Note that while these alternatives may offer relief, their effectiveness can vary from person to person, and some may still experience side effects. Therefore, individual experiences and healthcare guidance should always be considered when exploring these options.

Frequently asked questions

Yes, Benadryl can interact with several other medications, enhancing side effects such as drowsiness and dry mouth. It's particularly important to avoid combining it with other CNS depressants like alcohol, opioids, and certain anxiety medications. Always consult a healthcare provider or pharmacist before combining Benadryl with any other prescription or over-the-counter medications.

Although Benadryl is not known to cause physical dependency, there is a risk of developing a psychological dependency, especially when used regularly as a sleep aid. Over time, individuals may rely on it to fall asleep, which can mask underlying sleep disorders. If sleep issues persist, it's advised to seek medical advice for safer, long-term solutions.

Yes, individuals with asthma should use Benadryl with caution. While it can relieve allergic reactions, which may trigger asthma symptoms, its sedative effects can potentially worsen respiratory issues. Always consult with a healthcare provider before using Benadryl if you have asthma.

Benadryl is generally considered safe for short-term use during pregnancy and while breastfeeding, but it should be used under the guidance of a healthcare provider. During pregnancy, it's classified as a Category B medication, indicating no demonstrated risk to the fetus in animal studies. For breastfeeding mothers, small amounts of diphenhydramine can pass into breast milk, potentially causing drowsiness in the infant.

Ask a question about Benadryl and our team will publish the answer as soon as possible.

Possible short-term side effects

  • drowsiness
  • dry mouth
  • dizziness
  • nausea and vomiting
  • constipation
  • blurred vision
  • confusion

Possible long-term side effects

  • cognitive decline
  • sleep quality disruption
  • increase in tolerance
  • anticholinergic syndrome
  • heart problems

Ingredients to be aware of

  • diphenhydramine


  • relief from itching, hives, nasal congestion
  • sleep aid
  • allergy symptom relief

Healthier alternatives

  • loratadine (claritin)
  • cetirizine (zyrtec)
  • fexofenadine (allegra)
  • fluticasone (flonase)
  • azelastine (astelin)
  • ketotifen (zaditor)
  • melatonin
  • valerian root
  • lavender

Thank you for your feedback!

Written by Dr. Becky Maes
Published on: 04-30-2024

Thank you for your feedback!

Written by Dr. Becky Maes
Published on: 04-30-2024

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