- The most common side effects associated with Benadryl are related to its sedating action. The person might feel tired, drowsy or sleepy, be confused and have problems with coordination.
- Other side effects include blurred or double vision, difficulty urinating, dizziness, heart palpitations, increased heart rate, irritability, low blood pressure, nervousness, tremors, stomach upset, loss of appetite and nausea.
- Some side effects have been reported infrequently. These include chills, constipation or diarrhea, dry mouth, euphoria, fatigue, increased perspiration, sensitivity to sunlight and skin tingling or numbness.
- Benadryl exaggerates the sedating effects of alcohol, benzodiazepine anti-anxiety drugs, narcotic pain medications, tricyclic antidepressants and some blood pressure medications.
- People with certain conditions may not be able to use Benadryl. These include asthma, cardiovascular disease, enlarged prostate gland, glaucoma, high blood pressure and hyperthyroidism.














