Promethazine: Difference between revisions

Promethazine is a direct antagonist of histamine H1 receptors, whereas [[diphenhydramine]] is an inverse agonist. It is also an antagonist of muscarinic acetylcholine receptors, which is likely the cause of sedation and delirium that occurs with higher doses. It blocks dopaminergic D2 receptors, but weakly. {{citation needed}}

==Subjective effects==

{{EffectStub}}

*'''[[Effect::Sedation]]''' - Promethazine causes pronounced sedation and a general feeling of slowness, usually with the feeling of not wanting to move.

*'''[[Effect::Physical euphoria]]'''

**'''[[Effect::Muscle relaxation]]''' - This can lead to a very pleasant feeling of the entire body relaxing, feeling like warm gel. It similar to but distinct from an [[opioid]]'s physical euphoria. {{citation needed}}

*'''[[Effect::Increased heart rate]]''' and '''[[Effect::Increased blood pressure]]'''<ref>Tsay, M. E., Procopio, G., Anderson, B. D., & Klein-Schwartz, W. (2015). Abuse and intentional misuse of promethazine reported to US poison centers: 2002 to 2012. Journal of addiction medicine, 9(3), 233-237. | PubMed Link: https://www.ncbi.nlm.nih.gov/pubmed/25822213</ref> - Anticholinergic activity at muscarinic acetylcholine receptors causes these effects.

*'''[[Effect::Anxiety]] or [[Effect::Anxiety suppression]]''' - Anxiety rarely occurs in high doses and may occur as a result of delirium.{{citation needed}} Usually, promethazine acts as an [[anxiolytic|anti-anxiety]] agent.

*'''[[Effect::Delirium]]''' and '''[[Effect::Confusion|confusion]]'''<ref>Tsay, M. E., Procopio, G., Anderson, B. D., & Klein-Schwartz, W. (2015). Abuse and intentional misuse of promethazine reported to US poison centers: 2002 to 2012. Journal of addiction medicine, 9(3), 233-237. | PubMed Link: https://www.ncbi.nlm.nih.gov/pubmed/25822213</ref> -  In low to moderate doses, promethazine presents a harmless sense of being confused or delirious. In high doses and overdose, it can become (but rarely does) so severe that the patient or user experiences excited delirium, a state of severe agitation and confusion.

===Experience reports===