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Choline is a nutrient chemically similar to B-vitamins needed for proper cell membrane production and muscle work.

Histamine is a natural product derivate of the amino acid histidine, which according to Wikipedia is:

involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus.

Till this day, any "anticholinergic drug" I learned about was also said to be "Antihistamine drug" (and vice versa).

Is any anticholinergic necessarily antihistamine?

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  • I personally do not find choline chemically similar to the class of b vitamins. Also, choline is necessary for the production of important molecules, namely posphatidylcholine (a membrane lipid), acetylcholine (the neurotransmitter) and SAM (a universal methyl-group donor). The term „anticholinergic“ refers to the blocking of acetylcholine receptors, but it has nothing to do with choline (a bit unfortunately named)
    – Narusan
    Commented Apr 16, 2022 at 15:58

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Anticholinergic medications are called this way because they block transmission via the neurotransmitter acetylcholine. To be more precise, there are different types of acetylcholine receptors: nicotinergic and muscarinergic acetylcholine receptors. What we refer to as anticholinergica are usually selective inhibitors of the muscarinergic receptors. By this, they inhibit parasymphatic transmition and this is why they are also called (maybe a better term) parasympatholytics.

Anti-histaminic drugs however block the various histamine receptors.

In principle, anticholinergic and antihistaminic drugs are separate agents. The most common anticholinergic drugs are atropine, butylscopalamine and scopolamine.

Atropine has a (very low) affinity for histamine receptors and could therefore be considered anti-histaminic; but I have not found references whether it actually has an effect on humans in vivo. I could not find anything related to scopolamine and butylscopalamine.

In clinical practice, anticholinergic drugs are not considered antihistaminic drugs, and vice versa antihistaminic drugs are not considered anticholinergic.

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    So the name "anticholinergic" is misleading and it should have been "antiacetylcholinergic". Okay are antiacetylcholinergic generally antihistamine? I get the impression that no, there is no base to say that generally they effect the same receptors; in many cases they do, but NOT in general. You might want to edit based on my comment.
    – freethinker
    Commented Apr 16, 2022 at 23:55
  • @askerie As I said in my answer, none of the known and used anti(acetyl)cholinergic parasympatholytic drugs have a relevant antihistaminic effect.
    – Narusan
    Commented Apr 17, 2022 at 0:17
  • Would you say that some or all of the known antihistamine drugs have at least a weak antiacetylcholinergic effect?
    – freethinker
    Commented Apr 17, 2022 at 7:32

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