This pilot study evaluates the efficacy, safety, and tolerability of topical latanoprost acid in adult women with female pattern hair loss, with a minority of participants diagnosed with chronic telogen effluvium. In this randomized, double-blind, single-center, dose-ranging trial, participants receive latanoprost acid 0.01%, 0.05%, or 0.1% applied once daily for 6 months; a small vehicle group is included to support masking and assess tolerability. The primary outcome is the within-participant change in target-area hair count (hairs/cm²) from baseline to Month 6. Secondary and exploratory outcomes include follicular-unit distribution (percent of 1-, 2-, and 3-hair units), number of yellow dots, and patient-reported outcomes.