Taking Benadryl With Milk Thistle

In our latest question and answer, the pharmacist discusses whether or not there is an interaction between Benadryl and milk thistle.

Taking Benadryl With Milk Thistle
May 24, 2018

Simone asked

Is it safe to take Benadryl with milk thistle?


Milk ThistleThere is no known drug interaction between Milk Thistle and Benadryl. In addition, they don't share a similar side effect profile and there is little risk of either causing additive adverse reactions. They are considered safe to take together.

Milk Thistle

Milk Thistle (Silybum marianum) is a plant that is often used in over the counter supplements products for its protective effects on the liver protection and to treat liver diseases. It has also been used as an antioxidant and to treat cancer.

Milk thistle’s exact mechanism of action in the body is not known but it is thought to contain a variety of constituents (e.g. silybin A, silybin B, isosilybin A, isosilybin B) that have antioxidant and free radical-scavenging actions.

Side effects seen with milk thistle include:

  • Stomach upset
  • Diarrhea
  • Nausea and vomiting
  • Weakness

It is typically taken as an oral tablet, but it can be given as an intravenous infusion for certain indications. The typical dose is between 100mg and 500mg two to three times daily.


Benadryl (diphenhydramine) is a first generation antihistamine that is used for a variety of indications including:

  • Allergic reactions
  • Seasonal allergies
  • Insomnia

Due to the sedating properties of Benadryl, it is also commonly used to help patients fall asleep and is a component of many over the counter sleep aids, including Tylenol PM.

  • There is no interaction between Benadryl and milk thistle. They are safe to take together.

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