Hormone replacement therapy (HRT) in Cluster Headache typically involves using exogenous testosterone or testosterone derivatives to potentially modulate hypothalamic function and reduce headache frequency. The mechanism likely involves suppressing gonadotropin-releasing hormone (GnRH) and stabilizing hypothalamic neural networks, which are implicated in the pathogenesis of Cluster Headache. By altering hormonal milieu and neurological signaling, HRT can reduce the severity and frequency of cluster headache episodes in some patients.