Why is a progestogen added to menopause hormone therapy?

Menopause hormone therapy comes in more than one form. For someone who still has a uterus, estrogen is generally not prescribed on its own; a progestogen is given alongside it. For someone who has had a hysterectomy, estrogen alone is more usual.

The reason is the lining of the uterus. Estrogen on its own stimulates that lining, and unopposed stimulation over time is associated with an increased risk of endometrial cancer. The progestogen counteracts that effect, which is why the combination exists rather than being an added extra.

Which formulation, which route and for how long are decisions that depend on your own history, and the balance of benefit and risk genuinely differs from person to person. The National Cancer Institute fact sheet and the NHS pages are good preparation for that conversation, not a substitute for it.