Comment · Wed, August 10, 2016 · Ceretropic & Nootropics Depot
How safe are second generation antihistamines?
Original post in this thread
tkavalanche24 · 12 points
How safe are second generation antihistamines (like Zyrtec) for long term brain health and overall health? I am aware that the first gen antihistamines like benadryl are anticholinergic, can lead to alzheimer's and should be avoided. Should I shy away from second gen antihistamines and try to address my allergic rhinitis and nasal congestion without drugs?
What they were answering
IsNotANovelty · 2 points
I've suffered from year-round allergies my entire life and have taken a second-generation antihistimaine daily for years. I used to use cetirizine every day, but switched to fexofenadine which eliminated sedation (aka "brain fog") caused by cetirizine. This wasn't just my subjective experience, it's a much more commonly reported side effect with cetirizine and there's science behind why.
It also seems that sedation with cetirizine increases with larger doses.
However, it's also been shown that neither cetirizine nor fexofenadine have any significant anticholinergic action \(as opposed to lordatine, which does exhibit anticholinergic action similar to first-generation antihistamines, though, owing to its low BBB penetration, the risk is still likely very low\). (The sedation caused by these drugs is mostly brought on by CNS antihistamine action itself.)
So, to answer /u/tkavalanche24's question, I would say that cetirizine (Zyrtec) and fexofenadine (Allegra) are your best bet for daily antihistamines if you are worried about ant…
u/MisterYouAreSoDumb · Ceretropic & Nootropics Depot
I've tried every antihistamine under the sun, and many natural alternatives. Nothing works as well as cetirizine does. Fexofenadine works about 85% as well as cetirizine for me. While I do feel there are acute central effects on my energy, the complete elimination of my symptoms is worth it. It's also been my steady state for 15 years. So my baseline is pretty much built off it. On paper, fexofenadine seems like it would be a better alternative for me. However, real world it just does not give the same effectiveness for my specific symptoms as cetirizine. Perhaps there is a central mechanism with my specific disorder, and more BBB permeation is crucial to alleviating the symptoms.