Hi, welcome to justanswer, Benadryl can produce urinary retention and painful urination. Benadryl has anticholinergic effects , which can produce inadequate contraction of the bladder muscles and urinary retention. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Khanna on benadryl zyrtec interaction: May not be a good idea. What are your symptoms sometimes a doctor may add steroids and other instructions to control severe allergic Rhinitis Hello! For the past month I have had random hives appear all over my body. And I mean random, I go days without having one single hive and then all of a sudden patches of hives appear! Hello, Hives result from dilation of capillaries allowing fluid to leak out into the surrounding tissue, the epidermis.They are red, itchy, raised areas of skin that appear in varying shapes and sizes. Benadryl (Diphenhydramine) medication blocks the actions of histamine, a naturally occurring substance in the body that causes allergy symptoms. If this does not work, you can give a Chihuahua Benadryl for car sickness if it is only done on occasion and by following the recommended dosing. Dog hives are a severe allergic reaction that usually appears on your dogs skin within thirty minutes and if left to heal on its own can disappear in about twenty four hours. Benadryl Brand Name Benadryl Common Name diphenhydramine (allergy) In this drug factsheet: How does this medication work? What will it do for me? How should I use this medication? Doctors give unbiased, trusted information on the benefits and side effects of Benadryl to treat Food Allergy: Dr. Ferguson on food allergies and benadryl: No, zyrtec (cetirizine) does not work to prevent you from getting an allergic reaction to food or to treat food allergies. Food allergies can present with different clinical symptoms and can. Explains the medication diphenhydramine (Benadryl), a drug used for the relief of nasal and non-nasal symptoms of various allergic conditions such as seasonal hay fever, allergic conjunctivitis, insomnia, and motion sickness.