Benadryl Amitriptyline Drug Interaction

The pharmacist discusses the potential drug interaction between Benadryl and amitriptyline.

Jul 03, 2018

Johnathan asked

I take amitriptyline to help sleep once in awhile but it often doesn't do the trick. Is it okay to take with Benadryl?

Answer

There is a moderate drug interaction between Benadryl and Amitriptyline. The use of these medications together may not be ideal as the side effects of each can be additive and result in potentially harmful outcomes.

Amitriptyline is a tricyclic antidepressant, and is used for the treatment of depression (becoming less and less used as new and safer drugs are becoming available). It works by increasing various neurotransmitters in the brain (e.g. serotonin) that may be altered in individuals suffering from depression. Some of the common side effects of this medication are:

  • Constipation
  • Less urinary frequency
  • Abdominal cramping
  • Drowsiness

Benadryl is an antihistamine that is also known to have drying side effects due to its anticholinergic properties. Some of the common side effects associated with the use of Benadryl are:

  • Dry mouth
  • Constipation
  • Difficulty urinating
  • Decrease in mucus production
  • Sedation
  • Drowsiness

Additive Side Effects Of Benadryl And Amitriptyline

Despite not having the same use, Benadryl and amitriptyline have similar side effects which can be additive when used together. These additive toxicities must be considered before starting or recommending the use of Benadryl as serious complications including severe constipation, drowsiness and confusion can occur. In addition, be sure to ask your doctor regarding the use of the medications if you have a history of:

  • BPH (enlarged prostate)
  • Narrow angle glaucoma

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