Long-term use of anticholinergic drugs like Benadryl, some antidepressants, and others has been linked to increased risk of developing dementia. Benadryl (diphenhydramine) is a brand-name, over-the-counter medication that’s classified as an antihistamine. It’s used to help relieve symptoms of hay fever (seasonal allergies), other. Benadryl Injection official prescribing information for healthcare professionals. Includes: indications, dosage, adverse reactions, pharmacology and more. Allegra (fexofenadine) is effective at reducing symptoms for seasonal allergies and chronic hives without significant drowsiness, unlike Benadryl. 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. 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 (Diphenhydramine) is great for allergies, but curl up on the couch after taking it and get ready for a nap. Xyzal (Levocetirizine) is good for treating allergy symptoms, but it can cause drowsiness. Benadryl Overdose – Causes, Effects and Treatment. Benadryl or Diphenhydramine is an antihistamine medicine that cures symptoms of allergies, insomnia, hay fever, and the common cold. 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 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.