Antihistamine
The vast majority of marketed H-antihistamines are receptor antagonists and only a minority of marketed compounds are inverse agonists at the receptor. Clinically, H-antihistamines are used to treat allergic reactions and mast cell-related disorders. Sedation is a common side effect of H-antihistamines that readily cross the blood–brain barrier; some of these drugs, such as diphenhydramine and doxylamine, are therefore used to treat insomnia. H-antihistamines can also reduce inflammation, since the expression of NF-κB, the transcription factor the regulates inflammatory processes, is promoted by both the receptor's constitutive activity and agonist (i.e., histamine) binding at the H receptor.
Hashish
It has been claimed that the user’s psychological and physiological needs will influence the response and that the user must cooperate with and facilitate the effects. Therefore, the effect of the physical and interpersonal setting is strong and usually controls the underlying tone of the experience. Generally the intensification of sensation and increased clarity of perception have been reported. Short lived adverse effects have also been reported, including psychotic states following heavy consumption. Regular users are at risk of dependence. Especially people with major mental illnesses e.g. schizophrenia are vulnerable as hashish provokes relapse and aggravates existing symptoms.