Does Hormone Replacement Therapy Influence Melasma Development? A Review of the Evidence and Management Guidelines

BACKGROUND: Melasma is a common hyperpigmentation disorder influenced by ultraviolet exposure, genetics, and hormonal factors. Although associations with pregnancy and oral contraceptives are well established, the impact of hormone replacement therapy (HRT) on melasma is poorly researched. OBJECTIVE: The aim was to evaluate existing evidence on the relationship between HRT and melasma and propose evidence-based management guidelines. METHODS AND MATERIALS: A literature search of PubMed, Embase, and Scopus was conducted. Studies involving oral oestrogen-only HRT, combined HRT, transdermal oestrogen, topical oestrogen, and vaginal oestrogen were included. Guidelines were proposed based on the strength of evidence available. RESULTS: Evidence is limited and largely comprises case reports. High-dose oral oestrogen-only HRT has the strongest documented association, with case reports suggesting an association to forearm melasma in women with Fitzpatrick types III-VI. Case reports exist for combined oral and transdermal HRT, whereas topical and vaginal HRT formulations have minimal evidence to support their association with melasma. In vitro fertilization has no reported associated cases of melasma. CONCLUSION: HRT-associated melasma is underrepresented in the literature. Clinicians should counsel at-risk women on melasma risk and ensure strict photoprotection. Prospective studies are needed to clarify melasma risk across different HRT formulations.