We touched on this topic a few years ago, but it's always a good idea to go back and re-evaluate such topics in case any new information has come to light.
This is especially true for potential drug interactions concerning CBD (cannabidiol) as it has just exploded in popularity (and use) quite recently.
Not only has the over the counter (OTC) use of CBD skyrocketed, it is now available as a prescription product, Epidiolex, which is indicated for the treatment of rare seizure disorders.
After reviewing available information for Benadryl and CBD respectively, there doesn't appear to be any changes to what we wrote about previously...that there is no specific drug interaction that we know of, but they should still be used cautiously since both can cause sedation, drowsiness, and dizziness.
Our very own drug interaction checker (PharmacistAnswers Drug Interactions), which utilizes the DrugBank database, states the following regarding combining CBD and Benadryl:
Cannabidiols are capable of causing adverse effects such as dizziness, confusion, sedation, somnolence, and others to varying degrees. The concomitant use of cannabidiols with central nervous system depressants that can cause similar kinds of adverse effects can subsequently additively increase the risk, incidence, and/or severity of central nervous system depression for patients.
Benadryl (diphenhydramine) is a commonly used over the counter first-generation antihistamine. It does have 'central nervous system depressant' effects, which is why it is often used as a sleep aid...it makes you tired and drowsy.
The risk here of using CBD and Benadryl together is the additive (i.e. combined) central nervous system depressant effects. In other words, you may feel these effects more pronouncedly.
The good news is that really dangerous CNS depressant effects, like shallow breathing and respiratory arrest, aren't known to happen on these drugs (unlike other drug combos like benzodiazepines and opioids).
The prescribing information for Epidiolex, which again is a prescription CBD product that often calls for very high doses (hundreds to thousands of milligrams per day) only states the following regarding the interaction with CNS depressants:
CNS depressants, including alcohol, could potentiate the somnolence and sedation effect of EPIDIOLEX. Prescribers should monitor patients for somnolence and sedation and should advise patients not to drive or operate machinery until they have gained sufficient experience on EPIDIOLEX to gauge whether it adversely affects their ability to drive or operate machinery.
All in all, if you are just combining CBD and Benadryl at night, you shouldn't have much of an issue...just the additive drowsiness as discussed.
SummaryCombining CBD (cannabidiol) and Benadryl (diphenhydramine) cause result in additive sedation, drowsiness and dizziness. Taking them together during the day could impair your ability to concentrate and complete tasks that require concentration, like driving. Taking them together before bed likely shouldn't cause any significant issues.