Diphenhydramine Side Effects
Common Side Effects
Based on the limited information from prescription diphenhydramine products, the most common side effects of diphenhydramine include:
- Sedation (a feeling of sleepiness and reduced anxiety)
- Coordination problems
- Indigestion or heartburn
- Thickening of bronchial secretions (chest mucus).
Other reported side effects include:
- Sensitivity to the sun
- Excessive sweating and/or chills
- Dry mouth, nose, or throat
- Restlessness, excitation, nervousness, or irritability
- Shakiness (tremor)
- An unusual, pleasant feeling (euphoria)
- Unusual sensations, such as tingling or numbness
- A spinning sensation (vertigo)
- Loss of appetite, nausea, or vomiting
- Diarrhea or constipation
- Nasal stuffiness
- Early menstrual period.
You may experience some or none of the diphenhydramine side effects listed in this article. Unfortunately, there is no way for your healthcare provider to know beforehand if you will have side effects from a medicine that you have never tried. Therefore, make sure to let your healthcare provider know if you develop any side effects while taking the drug or if something "just does not seem right." While it may not be a side effect, your healthcare provider will be able to diagnose and treat the problem.