Mechanism

Histamine

Biogenic amine with a dual role: as a mediator of allergic inflammation (skin, mucous membranes) and as a central neurotransmitter synthesized in the tuberomammillary nucleus of the hypothalamus. In the brain it regulates wakefulness, attention, appetite, and motivation. Classic H1 antihistamines (diphenhydramine) cause drowsiness because they block this central pathway.

Effect by goal · level of evidence

Anxiety and histamine intolerance

modulates Low-moderate clinical (A)

Somatic picture

'Histamine intolerance' (intestinal DAO deficiency) can manifest with anxious somatic symptoms: tachycardia, hot flashes, headache, free-floating anxiety after foods rich in histamine (wine, aged cheese, oily fish).

View the study (review) →

Wakefulness and alertness

increases Very high physiology (A)

Insomnia target

Central histamine maintains wakefulness. H1 antihistamines that cross the BBB (diphenhydramine, doxylamine, chlorpheniramine) cause sedation; second-generation ones (loratadine, cetirizine) barely do.

View the study (review) →

Allergy and inflammation

increases Very high physiology (A)

Basis of allergy

Released by mast cells and basophils: hives, rhinitis, asthma, anaphylactic shock. Classic target of peripheral H1 antihistamines.

View the study (review) →

Gastric acidity

increases Very high physiology (A)

H2 target

H2 receptors on gastric parietal cells stimulate acid secretion. Ranitidine and famotidine (H2 blockers) treat ulcer and reflux.

View the study (review) →

Information, not medical advice. Scientific evidence reflects the quality of the studies.