Does Metamucil Interact With Benadryl Or Prednisone?

Thanks so much for your question Maxine!

I'm sorry to hear you've had problems in the past getting a CT scan (also known as a 'CAT' scan). It's not uncommon to pre-medicate with certain drugs, like Benadryl and prednisone, to reduce the risk of a reaction to the contrast media used for the scan. This is especially true if you have had a reaction in the past.

Metamucil With Benadryl And Prednisone

In regard to taking both of these drugs (Benadryl and prednisone) with Metamucil (a psyllium fiber product), you should not take them at the same time.

This is a general rule of thumb for fiber products in general.

Metamucil, being a fiber, can significantly affect the absorption of drugs if taken at the same time. Generally, fiber decreases both the rate and extent of absorption of other drugs given with it since fiber forms a gel-like substance in the stomach when ingested. This may make these medications less effective.

You should, ideally, take any drugs at least 30-60 minutes before taking a fiber product like Metamucil or at least 2 hours after.

If you are scheduled for a CT scan on a certain day, I would just take your pre-medication regimen of Benadryl and prednisone as directed by your doctor and simply take your Metamucil dose later in the day to avoid an interaction.

Final Words

Thank you so much again for reaching out! Please contact us again if anything else comes up!