Cyproheptadine

Cyproheptadine is a first-generation antihistamine that functions as a non-selective serotonin antagonist, and Ray Peat considered it a uniquely systemic tool for removing the brakes on metabolic rate. 2 Originally developed as an anti-allergy drug in the tricyclic class, it was subsequently discovered to block serotonin receptors, and Dinkov notes it also possesses anticholinergic properties, blocking the receptors through which estradiol mediates its pro-inflammatory and growth-promoting effects. 1 By antagonizing histamine, serotonin, and acetylcholine simultaneously, cyproheptadine renders estrogen much more benign and directly addresses the mediators of stress-induced metabolic suppression. 2

Peat emphasized that cyproheptadine is effective for insomnia, irritable bowel syndrome (IBS), and nocturnal episodes of asthma or epilepsy-like conditions, but he consistently warned that dosing must begin extremely low. 2 He recommended starting with half a milligram to one milligram at bedtime to judge sensitivity, as even 4 mg can make some people too torpid to function the next morning. 2 Roddy relayed that Peat considered 4 mg a substantial dose, and that individuals who tolerate 16 mg or more without sedation likely have an intestine producing a massive amount of serotonin and histamine. 3 Peat noted that the drug’s effects can persist for days after symptoms stop, and that small amounts are safe for daily, long-term use. 2

The drug’s mechanistic profile extends beyond receptor antagonism. Dinkov has written that cyproheptadine antagonizes aldosterone, giving it diuretic effects similar to spironolactone. 4 Peat described it as opposing not only serotonin but also adrenaline, cortisol, estrogen, and TLR-4, while preventing soft tissue calcification. 5 Dinkov added that drugs inhibiting serotonin synthesis are currently in clinical trials for morbid obesity and type 2 diabetes, causing rapid and sustainable weight loss without caloric restriction, and that cyproheptadine’s serotonin blockade achieves a comparable unleashing of metabolic rate. 1 He also noted that most SSRI antidepressants actually raise allopregnanolone levels in the brain, and some doctors prescribe cyproheptadine alone as an antidepressant therapy, acting in opposition to the serotonergic properties of SSRIs. 6

Regarding specific cautions, Peat advised that thyroid and the dependent neurosteroids are the foundational regulators, with reactive adrenaline, serotonin, nitric oxide, and prostaglandins as the immediately involved factors in insomnia, and that keeping endotoxin absorption low through diet or antibiotics can often make a significant difference. 2 Dinkov addressed a common warning against cyproheptadine use in benign prostatic hyperplasia (BPH), attributing it to high-dose anticholinergic urine retention rather than any direct harm to the prostate, and dismissed the peptic ulcer contraindication as contradictory since cyproheptadine blocks H2 receptors used to treat ulcers. 8 Peat recommended no more than 2 mg daily due to potential liver issues, though studies in children with functional gastrointestinal disorders have used 4 mg or more. 4 He also noted that combinations of coffee, aspirin, progesterone, thyroid, vitamin D, and calcium can usually achieve the same broad-spectrum goals as cyproheptadine without the side effect of weight gain. 5