Taking Benadryl Before Alcohol To Lessen Allergic Reaction

Don asked

I have never been a big drinker of alcohol, but occasionally enjoy a glass of wine with dinner or a margarita. However, I recently developed an allergic reaction to alcohol in any form, even in cough syrup. My wife and I are planning a special evening out at a nice Italian restaurant and I would like to have a glass of wine with dinner. A friend recommended taking a Benadryl before I drink, saying he has the same issue. I was just wondering if it was safe, health wise, to do so. I know it can cause drowsiness but she would be driving if there are any issues at all. I just need to know if it’s actually safe or not.

Answer

Although true allergies to alcohol are rare, alcohol intolerance can cause flushing, hives, and stuffy or runny nose. Alcohol intolerance can be caused by other ingredients in alcoholic beverages including sulfites, grains, and histamine. Occasionally, a genetic variation of alcohol metabolizing enzymes can worsen the reaction to alcohol.

While taking diphenhydramine (Benadryl) could theoretically lessen the effect of histamine release associated with alcohol intake, it has not been proven as an effective treatment. In addition, there is a risk of combining alcohol with Benadryl.

Taking Benadryl with alcohol could cause an increased risk of drowsiness and may increase the effects of alcohol. This could have a significant effect on psychomotor impairment.

It may be a good idea to see your doctor or an allergist to get definitive information regarding what you are allergic to. If it is ethanol, you would certainly need to avoid allergic beverages. Benadryl may reduce symptoms slightly, but most likely wouldn't prevent them completely. 

If you do intend to try Benadryl before alcohol, be sure to take your dose about 90 minutes before alcohol intake. Benadryl doesn't prevent the release of histamine, but blocks histamine from binding to receptors. Peak histamine blocking effects occur about 90 minutes after intake.

It should be noted that if you have certain hypersensitivity reactions to ethanol, Benadryl won't work at all as these reactions are not mediated by histamine.

Alcohol Metabolism

Alcohol is primarily metabolized via alcohol dehydrogenase, aldehyde dehydrogenase, cytochrome P450 (CYP2E1), and catalase. The byproducts of alcohol include acetaldehyde and acetate and contribute to many of the negative effects.

Genetic variation of these enzymes causes varying degrees of alcohol metabolism—which is why everyone tolerates alcohol differently. This metabolism takes place mostly in the liver. CYP enzymes play a particularly important role in drug metabolism and drug interactions occur via the inhibition or induction of these enzymes. Alcohol does impact CYP enzymes, especially CYP2E1.

Disulfiram-like Reaction:

Some drugs may cause a “disulfiram-like reaction” when taken with alcohol. This can cause flushing, nausea, vomiting, and general “hangover effects”. These drugs inhibit aldehyde dehydrogenase which is crucial in metabolism of alcohol. Some of these drugs include disulfiram and chloramphenicol.

Disulfiram is actually used clinically to treat alcohol dependence since it makes drinking alcohol much less desirable. Benadryl does not cause a disulfiram-like reaction.  

Summary

Combining the use of alcohol with Benadryl can increase the risk of drowsiness and psychomotor impairment. In addition, it is unclear whether Benadryl will lessen the impact of alcohol intolerance. Caution would be recommended if attempting to prevent alcohol intolerance with Benadryl.