Does Benadryl Cause Nasal Congestion. Can benadryl cause a sinus infection. Antihistamines do not cause sinus infections. Whatever you were trying to treat with the antihistamines caused the sinus infection. What is unhelpful to hear is that for most cramps, we have no idea why they happen. Patients sometimes wonder if their medication is leading to their nighttime leg cramps and well, yes, some medications can. Benadryl Allergy & Sinus Headache. Generic Name: acetaminophen, diphenhydramine, and phenylephrine (a SEET a MIN oh fen, DYE fen HYE dra meen, and FEN il EFF rin) Diphenhydramine is benadryl & usually comes in 25 mg doses OTC. You can take 2 safely at a time. The max dose for 24 hours is 300mg, but have never heard of anyone taking this much, & definitely not all at once. New Benadryl Coupon For Canada Save $4.00 off any one Benadryl product This coupon is available in Print format only. Print coupon for Benadryl Here Coupon is currently not available This Benadryl coupon expiry date is unknown. Available for Buyer Be Aware: Benadryl is a Serious Drug. This common over-the-counter drug was the precursor to Prozac. It can make you drowsy, scramble your brain, and impair your driving more than alcohol. Diphenhydramine comes as a tablet, a rapidly disintegrating (dissolving) tablet, a capsule, a liquid-filled capsule, a dissolving strip, powder, and a liquid to take by mouth. Medscape - Hypersensitivity reactions, insomnia, antihistamine-specific dosing for Benadryl, Nytol (diphenhydramine), frequency-based adverse effects, comprehensive interactions, contraindications, pregnancy & lactation schedules, and cost information. What are the physical effects of Benadryl on the Digestive track and why? I realize Benadryl's primary design is to be an Antihistamine but after taking Benadryl (about 30 min later) my stomach to my large intestine starts to work normally again for about 4-1/2 more hours until it wears off. La difenhidramina se usa para aliviar el enrojecimiento, la irritación, la picazón y el lagrimeo de los ojos, los estornudos y la secreción nasal causados por la fiebre del heno, las alergias o el resfriado común.