Get Virtual Care
For Businesses
About Us
A member asked:
Why do some antihistamines make me drowsy?
5 doctors weighed in across 2 answers
Cross into brain: Older antihistamines, such as diphenhydramine, or chlorpheniramine, actually cross the barrier between the bloodstream and the brain. This causes many people to feel drowsy or sedated. It can make some people irritable, or even cause insomnia. For this reason, the "non-sedating" antihistamines were developed. These medications cause much less drowsiness, and are better tolerated.
Answered 3/1/2016
6.3k views
Antihistamines: Because they cross the blood brain barrier and trigger receptors that can lead to sedation. The only one that does not cross the blood brain barrier is allegra/fexofenadine.
Answered 4/22/2015
5.2k views
Related Questions
A member asked:
Do histamines (not antihistamine medications) make you drowsy? Antihistamines (no decongestants added) seem to make me more alert when allergies flare
A doctor has provided 1 answer
A member asked:
What is good otc antihistamine to take for someone have asthma..I take clarity sometimes but it makes me drowsy and sleepy..is allegra (fexofenadine) better?
A doctor has provided 1 answer
A member asked:
Besides doxylamine & diphenhydramine, what other OTC antihistamines cause drowsiness? Without a prescription.
4 doctors weighed in across 2 answers
A member asked:
Bitten by unknown insect. Redness and swelling to forarm. Marked with pen and doubled in size over 36hrs. Taking non drowsy antihistamines and icing?
A doctor has provided 1 answer
People also searched for:
Can drowsiness caused by antihistamines be treated or minimized at a necesary event?
What is an extra drowsy antihistamine i can ask my doctor for?
Can Claritin (loratadine) non-drowsy antihistamine still cause drowsiness?
Can you take generic multi symptom night time medicine with night time Thera-Flu? I don't usually get drowsy from just one dose of antihistamine. I have adhd so it's hard for me to get sleepy from that. So is it okay to take both?
What non drowsy OTC antihistamine can I take for itching caused by percocet for post op pain?
Didn't find what you're looking for?
90,000 U.S. doctors in 147 specialties are here to answer your questions or offer you advice, prescriptions, and more.
Ask your questionMore of what we treat
Download HealthTap
Video visit and message your doctor
