Can Benadryl Cause Loose Stool In Dogs?
Can Benadryl Cause Loose Stool In Dogs? Selmer: The most common side effects of Benadryl are lethargy, dry mouth and urine retention. Diarrhea, vomiting and decreased appetite are possible, but not common. Can antihistamines cause diarrhea in dogs? Side effects of antihistamines in dogs include drowsiness and lethargy. Some dogs also get diarrhea or nausea.