Can Benadryl Cause Constipation?

Benadryl Use

Benadryl is a popular antihistamine used most often to treat symptoms associated with allergies and the common cold. However, Benadryl can also be used to relieve symptoms related to bee stings, poison oak/ivy and chicken pox. Benadryl contains diphenhydramine which is the active ingredient that classifies this drug as an antihistamine. Other common complaints that can be relieved with Benadryl include: coughing, motion sickness, itching, runny nose, sneezing, watering eyes, hives, rashes, inability to fall asleep and benign forms of Parkinson's Disease.

Benadryl Side Effects

Although the side effects of Benadryl are not severe, if experienced, they can cause discomfort and may require using an alternative treatment. One of the most common side effects of Benadryl is constipation. Other side effects of Benadryl include: diarrhea, drowsiness, dizziness and nausea. In some individuals, especially children, Benadryl may cause excitement and the inability to sleep. While excitement and the inability to sleep are actually symptoms commonly treated with Benadryl, often these side effects are experienced in individuals being treated for other symptoms, such as allergies or itching.

Treating Constipation Caused by Benadryl

If an individual taking Benadryl experiences constipation, the constipation will continue as long as the drug is taken. If constipation is not causing problems such as stomach ache or nausea, a slight change or modification to the diet may help relieve some of the discomfort associated with constipation. Modifying the diet by increasing the amount of fiber can help improve or eliminate constipation. Fiber can be added by increasing the amount of whole grain breads and cereals, oatmeal, fresh fruits and vegetables eaten daily. Additionally, drinking prune juice can prove beneficial. If prune juice is not desirable, mixing prune juice with apple juice, using equal portions of each is often well tolerated. If constipation continues after increasing dietary fiber, a mild laxative may be necessary. If the individual is a child, check with the doctor before initiating laxatives.


Due to Benadryl causing dizziness, drowsiness and sleepiness in some individuals, the use of dangerous machinery, driving an automobile or performing dangerous activities is not advised until one becomes familiar with the personal side effects of Benadryl. Additionally, individuals should avoid drinking alcohol while taking Benadryl as alcohol may intensify these side effects.