Can You Take Benadryl With L-Theanine, Glycine And Inositol?

In our latest question and answer, our pharmacist discusses whether or not Benadryl interacts with glycine, l-theanine, or inositol dietary supplements.


Are there any known interactions between Benadryl and supplements like glycine, L-theanine, and inositol that are supposed to help with sleep? I took Benadryl but also need to take my other supplements, but wanted to check if they’re ok to take together.

Asked by Brittany On Jan 20, 2023

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jan 23, 2023
Last updated Dec 08, 2023

Key points

  • Aside from the potential of additive sedative effects, there is no known interaction between Benadryl, L-theanine, inositol and glycine.


Thanks so much for reaching out. Based on the available evidence, there does not appear to be any drug interactions between Benadryl (diphenhydramine), glycine, L-theanine, and inositol aside from the fact that there may be some additive sedation that occurs.


Benadryl is a sedating antihistamine and is commonly used as a sleep aid. Several of the supplements you mentioned, such as glycine and L-theanine, are also known to have sedative effects. Therefore, the combination could theoretically have additive effects in this regard.

You can read more interaction details via the link below:

This interaction would be considered to be relatively minor, as it appears you are using these to help promote sleep. Just be aware that you could feel more sedated than usual with the combination.

Inositol, although sometimes used for anxiety and in sleep formulas, is not thought to have significant sedative effects.

So, aside from the additive sedation I talked about here, there is no evidence to suggest that anything you mentioned will affect the absorption of Benadryl or how it works.

Final Words

I appreciate you reaching out!

We do have a 'drug-herbal interaction checker' that is free to use if you are interested in looking up any other potential interactions.

Of course, we are always available as well to answer anything that comes up. Reach back out anytime!


  • Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study., PubMed
  • GABA and l-theanine mixture decreases sleep latency and improves NREM sleep, PubMed

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Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

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