When used properly, Benadryl, a common brand name for the drug diphenhydramine, is very safe for dogs. However, over the. What is Diphenhydramine (Generic Benadryl)? Diphenhydramine is an antihistamine used to relieve allergy symptoms, insect stings, motion sickness, travel anxiety, and other conditions. When allergies or anxiety takes over your pet, you know how hard it is to watch them go through that pain. However, there is a solution: Benadryl for dogs. Drowsiness is one of the major side effects of some antihistamines, such as diphenhydramine (Benadryl) and doxylamine succinate (the antihistamine found in Nyquil). Benadryl Injection official prescribing information for healthcare professionals. Includes: indications, dosage, adverse reactions, pharmacology and more. Allergens are more prominent at different times of year. Our Allergy Calendar will help you find out the common seasons for different allergies in the UK. Benadryl for Cats: Although cats can take Benadryl, it has potential side effects, including hyperexcitability, diarrhea, decreased appetite and urination, dry mouth, vomiting and sedation. Benadryl can react with a variety of drugs; Drowsiness is a side effect of taking Benadryl for cats just as it is for humans.. Benadryl vs Benadryl Allergy. One of the more common medications that we get to read about, hear about, and probably purchase for immediate remedies for allergies for home use is Benadryl. Learn more about children’s BENADRYL® dosing, tips for reducing your child’s allergy symptoms and how to create an allergy action plan. Benadryl in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when Benadryl in the oral form is impractical. For use in parkinsonism, when oral therapy is impossible or contraindicated, as follows: parkinsonism.