Mixing Benadryl and Alcohol - A Comprehensive Guide to the Risks
Key points
- Intense Drowsiness and Dizziness: Making it difficult to stay awake and alert.
- Impaired Judgment and Coordination: Affecting your ability to make decisions, walk steadily, or react quickly.
- Increased Risk of Accidents: The combination significantly increases the risk of falls, injuries, and car crashes. The National Highway Traffic Safety Administration has noted that Benadryl can impair a driver's alertness more than alcohol, and mixing them makes driving exceptionally hazardous.
It’s a common scenario: you’ve taken an over-the-counter medication like Benadryl for allergies or a runny nose and later consider having a drink. Because Benadryl is so easily accessible, many people underestimate its strength and the potential dangers of mixing it with other substances. However, combining Benadryl (diphenhydramine) and alcohol is a risky decision that can lead to severe and even life-threatening consequences.
This article provides a comprehensive overview of why this combination is unsafe, detailing the immediate risks, long-term health effects, and crucial safety guidelines.
Why Mixing Benadryl and Alcohol Is So Dangerous
The primary danger lies in the fact that both Benadryl and alcohol are Central Nervous System (CNS) depressants. The CNS consists of your brain and spinal cord and controls most functions of your body and mind. CNS depressants work by slowing down brain activity, which results in a calming or drowsy effect.
When you take two CNS depressants together, their effects don't just add up—they multiply. This synergistic interaction can slow your CNS down to a dangerous degree, leading to significantly amplified side effects.
Immediate Risks and Side Effects
Even a single dose of Benadryl combined with one alcoholic drink can produce noticeable effects. The risks increase significantly with higher doses of either substance.
Enhanced Drowsiness and Impaired Coordination
The most immediate and common side effect is extreme sedation. This isn't just simple sleepiness; it can be an overwhelming drowsiness that severely impairs your cognitive function and motor skills. This leads to:
- Intense Drowsiness and Dizziness: Making it difficult to stay awake and alert.
- Impaired Judgment and Coordination: Affecting your ability to make decisions, walk steadily, or react quickly.
- Increased Risk of Accidents: The combination significantly increases the risk of falls, injuries, and car crashes. The National Highway Traffic Safety Administration has noted that Benadryl can impair a driver's alertness more than alcohol, and mixing them makes driving exceptionally hazardous.
Cognitive and Cardiovascular Effects
Beyond sedation, the mixture can cause a range of other serious symptoms:
- Confusion and Memory Problems: You may experience disorientation or have difficulty remembering events.
- Nausea and Vomiting: Both substances can irritate the stomach, and combining them worsens this effect.
- Dehydration: Alcohol is a diuretic, and both can lead to dehydration, causing headaches and dizziness.
- Respiratory Depression: In severe cases, the combination can slow your breathing to a dangerously low rate, potentially leading to unconsciousness, coma, or even death.
How Long Should You Wait Between Benadryl and Alcohol?
To avoid a dangerous interaction, you must allow the Benadryl to completely clear from your system before consuming alcohol. The active ingredient, diphenhydramine, has a half-life of approximately 7 to 12 hours in healthy adults. However, it can take up to five half-lives for a drug to be fully eliminated.
- For Adults: It is safest to wait at least 24 to 48 hours after your last Benadryl dose before drinking any alcohol.
- For Older Adults: The half-life of diphenhydramine is longer in seniors, ranging from 9 to 18 hours. Therefore, a waiting period of 36 hours or more is recommended.
Always consult your doctor or pharmacist for personalized advice, as factors like liver function, age, and other medications can influence how long the drug stays in your body.
Special Risks for Certain Groups
While mixing Benadryl and alcohol is unsafe for everyone, some individuals face an even greater risk.
Older Adults
According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), older adults are more sensitive to the effects of alcohol. When combined with Benadryl's sedative properties, this heightened sensitivity dramatically increases the risk of falls, confusion, and serious injury.
Individuals with Pre-existing Health Conditions
People with impaired liver function should be especially cautious, as both alcohol and Benadryl are metabolized by the liver. Mixing them can put extra strain on the organ. Those with respiratory conditions like sleep apnea or COPD are also at higher risk of dangerous respiratory depression.
Long-Term Consequences of Chronic Co-use
Repeatedly mixing Benadryl and alcohol can lead to severe, long-term health problems.
- Increased Risk of Dementia: Benadryl is an anticholinergic drug. Long-term use of strong anticholinergics has been linked to an increased risk of dementia. Heavy, chronic alcohol use is also a known risk factor for dementia. Combining them may amplify this risk.
- Cognitive and Memory Impairment: Both substances interfere with acetylcholine, a neurotransmitter essential for learning and memory. Chronic co-use can lead to lasting cognitive deficits.
- Disrupted Sleep Patterns: While the combination causes drowsiness, it disrupts the quality of your sleep, preventing restorative rest and leading to chronic fatigue.
Answering Common Questions
Can I use Benadryl for an alcohol flush reaction?
No. The "alcohol flush" or "Asian glow" is caused by a genetic inability to break down acetaldehyde, a toxic byproduct of alcohol metabolism. Using Benadryl to mask the redness is dangerous for two reasons:
- It does not solve the underlying problem of toxic acetaldehyde buildup.
- It introduces all the risks of mixing a CNS depressant with alcohol.
What about "non-drowsy" antihistamines like Claritin or Zyrtec?
Newer, second-generation antihistamines like loratadine (Claritin) and cetirizine (Zyrtec) cause significantly less drowsiness. However, the NHS and other health authorities still advise against drinking alcohol while taking any antihistamine, as some level of interaction and increased sedation can still occur.
What should I do if I accidentally mixed them?
If you have unintentionally consumed alcohol after taking Benadryl, prioritize your safety:
- Do not drive or operate any machinery.
- Stay in a safe place where you can rest.
- Drink water to stay hydrated.
- Monitor your symptoms closely.
- Seek immediate medical attention if you experience severe symptoms like extreme confusion, hallucinations, seizures, or difficulty breathing.
The Bottom Line: Prioritize Safety
Benadryl is an effective medication for allergies, but it is also a powerful drug that demands respect. The consensus among medical professionals is clear: do not mix Benadryl and alcohol. The potential for severe sedation, impaired judgment, and life-threatening complications is too high. If you are taking Benadryl, it is best to abstain from alcohol completely until the medication has cleared your system.
When in doubt about any medication interactions, always speak with your doctor or pharmacist.
References
- Healthline: Benadryl and Alcohol: The Dangers of Mixing Them
- Medical News Today: Benadryl and alcohol: Risks, how long to wait, and next steps
- GoodRx: Can You Mix Alcohol With Benadryl, Claritin, or Zyrtec?
- National Health Service (NHS): Common questions about diphenhydramine
- National Institute on Alcohol Abuse and Alcoholism (NIAAA): Harmful Interactions: Mixing Alcohol With Medicines
About the author
Ben Carter, PharmD, is a board-certified clinical pharmacist specializing in infectious diseases. He heads the antibiotic stewardship program at a large teaching hospital in Boston and is an assistant professor at a college of pharmacy.