The Hidden Cost of Antihistamines: How Blocking Histamine Silences Your Most Important Neural Network — section

In the gut: ACh is the dominant neurotransmitter of the enteric nervous system &#8212; your &#8220;second brain.&#8221; It directly controls intestinal contractions, coordinates the migrating motor complex (the cleansing wave that sweeps between meals), regulates mucus secretion from goblet cells, controls chloride secretion for mucosal hydration, and modulates epithelial barrier integrity. Without adequate cholinergic signaling, motility stalls, secretions dry up, and the mucosal surface becomes vulnerable.