How Fexofenadine Compares as a Non-Sedating Antihistamine
Welcome to the Allergy, Asthma & Immunology Innovations podcast. In a new series called The Itch Review, co-hosts Kortney, Payel Gupta, MD, and Michael Blaiss, MD, discuss the latest asthma and allergy research. This episode reviews the article “Why fexofenadine is considered as a truly non-sedating antihistamine with no brain penetration: a systematic review”, published in Current Medical Research & Opinion in July 2024.
Our panel starts by comparing first-generation “old-school” antihistamines (diphenhydramine) to newer options (cetirizine, loratadine and fexofenadine). Then, we dive into a systematic review that evaluated more than 60 studies, including PET brain-scan trials, Proportional Impairment Ratio (PIR) tests, driving simulator trials, and quality-of-life surveys.
The researchers wanted to know: Does fexofenadine ever cross the blood–brain barrier and make you drowsy?
You can listen to the podcast on ItchPodcast.com or download it for listening anytime, anywhere, at:
This podcast is for informational purposes only and does not substitute professional medical advice. Any mention of brands is also informational and not an endorsement. Always consult with your healthcare provider for any medical questions or concerns.
Thank you to Opella for sponsoring this podcast episode.
Key takeaways on ‘Why fexofenadine won’t make you sleepy’
- First- vs. second-generation antihistamines. Old antihistamines like diphenhydramine (Benadryl®) cross into the brain and cause drowsiness. Newer ones like cetirizine, loratadine and fexofenadine do not cross the barrier as easily. This makes them less sedative.
- H1-receptor occupancy. Special PET scans take pictures of your brain. They found that fexofenadine blocks less than 1% of the spots that cause sleepiness.
- PIR test results. Objective and subjective tests found zero significant drowsiness or slowed thinking when on fexofenadine compared to placebo (sugar pill).
- Driving & pilot safety. Simulator and pilot studies showed that people drove and flew just as well as people on a placebo.
- Real-world benefits. Using fexofenadine showed fewer missed school/work days, and it is safe for kids to take.
Timestamps for our episode about allergies and antihistamines
01:26 – What are allergy medicines?
07:07 – Why old allergy pills can make you sleepy
07:56 – What’s a systematic review?
10:47 – Does fexofenadine get into your brain?
17:48 – How we measure drowsiness (PIR tests)
20:16 – How much fexofenadine is taken
21:44 – Looking at tests on thinking and movement
22:03 – Driving test: fexofenadine vs. Benadryl vs. alcohol
23:46 – Flying test: pilots taking fexofenadine
26:52 – Quick look at other studies
29:46 – Our big learnings
31:50 – Why we need different allergy medicines
32:37 – Why doctors warn about old allergy pills
