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Natural progestogen (micronised)

Progesterone

Brand names: Cyclogest, Crinone, Utrogestan, Lutigest

Progesterone is the natural progestogen, used for luteal-phase and early-pregnancy support in assisted reproduction, as the progestogen component of menopausal hormone therapy, and to reduce preterm birth risk in selected women.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It acts on progesterone receptors to transform oestrogen-primed endometrium into a secretory state, support implantation and pregnancy maintenance, and oppose oestrogenic endometrial proliferation.

Prescribing in practice

  • When used to oppose oestrogen in women with an intact uterus, adequate progestogen exposure is essential to protect against endometrial hyperplasia and carcinoma.
  • Undiagnosed vaginal bleeding must be investigated before use, and it is contraindicated in active thromboembolic disorders.
  • Oral micronised progesterone commonly causes drowsiness and is usually taken at bedtime.

Monitoring

No routine blood monitoring is required; investigate any unexpected vaginal bleeding and review the indication periodically.

Counselling the patient

  • Take oral capsules at bedtime as they can cause drowsiness.
  • Use vaginal preparations exactly as directed for fertility or pregnancy support.
  • Report any unexpected vaginal bleeding.

Evidence & guidelines

Vaginal progesterone for prevention of preterm birth in women with a short cervix is supported by NICE guidance and randomised trial evidence.

Reference: NICE NG23/NG126; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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