Benadryl Caps

Overview

Benadryl (diphenhydramine), a sedating first-generation antihistamine, has a duration of action around 4 to 6 hours for most individuals, with maximum sedative effects occurring 1-3 hours after taking a dose. Certain factors can prolong this, however, including:

  • Age (65 +)
  • Liver impairment
  • Genetic metabolizing enzyme variations

Alcohol With Benadryl

When it comes to drinking alcohol with Benadryl, it is recommended that the combination be avoided.

Being a sedating antihistamine, drowsiness is a common effect of Benadryl, which is why it is often used as a sleep aid. Combining it with alcohol can cause additive effects, including significant drowsiness and psychomotor impairment.


How Long To Wait

There are really two questions here:

  • How long until the effects of Benadryl wear off?
  • How long until Benadryl is completely eliminated from the body?

How Long For Benadryl To Wear Off

In terms of how long it takes Benadryl to wear off, the effects only last around 4 to 6 hours. Therefore, alcohol shouldn't cause additive impairment after that time frame. However, since the duration of action can vary slightly by the individual, it is important for you to judge whether or not the drug is still affecting you, even after 6 hours.


How Long For Benadryl To Be Completely Metabolized

Now, if you want to completely avoid alcohol while Benadryl is still in your system, we have to look more closely at the metabolism of the drug.


The half-life of Benadryl is between 2 and 8 hours for most individuals. Based on this, it will be completely metabolized and eliminated from the body within 12 to 48 hours. Most studies report that the vast majority of diphenhydramine and associated metabolites, for most people, are excreted via the kidneys within 24—48 hours of a dose.


Based on the above information, if you are looking to completely avoid alcohol while Benadryl is in your system, you need to wait 24 to 48 hours.


Summary

  • The effects of one dose of Benadryl last around 4 to 6 hours, but can be longer in certain individuals (e.g. the elderly).
  • It takes around 24-48 hours for Benadryl to be completely metabolized from your system.
  • References
    1. Diphenhydramine: pharmacokinetics and pharmacodynamics in elderly adults, young adults, and children. JAMA Network
    2. Effects of terfenadine and diphenhydramine alone or in combination with diazepam or alcohol on psychomotor performance and subjective feelings. SpringerLink
    3. Identification of human cytochrome p450 isozymes involved in diphenhydramine N-demethylation. PubMed