3 doctors weighed in:
Strange side effects of benadryl (diphenhydramine)?
3 doctors weighed in

Dr. Lee Perry
Internal Medicine - Allergy & Immunology
2 doctors agree
In brief: Several
The most common side effect of taking too much Benadryl (diphenhydramine) would be excessive drowsiness.
Other possible side effects include dizziness, headache, constipation, urinary retention, and heart palpitations.

In brief: Several
The most common side effect of taking too much Benadryl (diphenhydramine) would be excessive drowsiness.
Other possible side effects include dizziness, headache, constipation, urinary retention, and heart palpitations.
Dr. Lee Perry
Dr. Lee Perry
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