Sammie asked
I use Miralax, one capful, on a daily basis for constipation. Is it safe to use Benadryl? Will it constipate me?
Answer
There are no known drug interactions between Benadryl and Miralax. However, long term use of Benadryl can cause constipation, which is what Miralax is generally used to treat. Benadryl should therefore be used only intermittently, as needed.
Benadryl
Benadryl is an antihistamine medication with the active ingredient diphenhydramine. Diphenhydramine is known to compete with and block histamine from binding to the histamine 1 receptor sites found on cells throughout the body. Histamine binds H1 receptors found on intestinal, respiratory, and blood vessel cells.
The primary effect of histamine release includes vasodilation, that is the dilation of blood vessels, which contribute to the symptoms observed during an allergic reaction (such as redness resulting from an increase in blood flow to an area). By competing with histamine for binding sites, diphenhydramine causes contraction of the blood vessels which aids in relieving symptoms of an allergic reaction, including nasal congestion, sneezing, or hives.
Benadryl is generally well tolerated but is known to cause sedation, dry mouth, dry eyes and constipation.
Miralax
Miralax is a medication used to treat occasional constipation. It contains the active ingredient polyethylene glycol 3350.
It is a laxative that exerts its effects by creating an osmotic gradient leading to an increase of water in the stool. This effect allows for softer and more frequently occurring bowel movements. Miralax is not absorbed in the body and will only exert its effects on the intestinal tract. Miralax may affect the absorption of other medications, however is not known to interact with Benadryl.
Summary
- Miralax can safely be taken with Benadryl. However, Benadryl can cause constipation and should only be used as needed.
