Question: can benadryl lower seizure threshold?
Answer: However, pseudoephedrine and dextromethorphan can also lower the seizure threshold and are common ingredients in many cold medications. Guaifenesin does not seem to be as much of a problem. Some people are also sensitive to antihistamines, so we suggest that you avoid diphenhydramine (Benadryl) and cetirizine (Zyrtec).