Drug Interaction Between Benaryl And Topamax (Topiramate)

In our latest question and answer, the pharmacist discusses the potential drug interaction between Benadryl (diphenhydramine) and Topamax (topiramate).

Jun 28, 2018

Cid asked

I take Topamax for migraine prophylaxis. Can I take Benadryl at night?

Answer

Both Benadryl (diphenhydramine) and Topamax (topiramate) act as central nervous system depressants and therefore, may have additive side effects with each. Potential side effects include:

  • Decreased alertness
  • Drowsiness
  • Falls
  • Confusion

In general, their use together isn't recommended unless discussed with your doctor first. If you do take both, it is important to not drive or operate machinery until you know how these drugs will affect you. 

There may be cases where your doctor recommends Benadryl solely for intermittent use (e.g. treating insomnia or allergic reactions) if you are taking Topamax. This is generally okay for most individuals as long as you are aware of the additive risk of side effects, such as sedation and adverse cognitive reactions. Use of both however generally isn't recommended in the elderly due to increased risk of falls.

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