What is Duphaston (dydrogesterone) and what are its indications, dosing regimens, contraindications, and potential side effects?

Duphaston (Dydrogesterone): Clinical Overview

Duphaston is an oral synthetic progestogen (dydrogesterone) with a molecular structure similar to natural progesterone, used primarily for hormone replacement therapy in combination with estrogen, luteal phase support in assisted reproduction, and treatment of progesterone-deficiency conditions including threatened miscarriage, dysmenorrhea, and irregular menstrual cycles. 1, 2

What is Dydrogesterone?

Dydrogesterone is a retroprogesterone with enhanced oral bioavailability compared to natural progesterone. Unlike other progestogens, it does not inhibit ovulation at standard doses and lacks estrogenic or androgenic properties, making it suitable across a woman's reproductive lifespan 2, 3.

Primary Indications

Hormone Replacement Therapy (HRT)

Dydrogesterone is recommended as a second-choice progestogen (after micronized progesterone) for endometrial protection in women with a uterus receiving estrogen therapy. 1

The 2021 Blood Reviews guidelines specify:

• Sequential regimens: 10 mg daily for 12-14 days per month when combined with estrogen
• Continuous regimens: 5 mg daily when avoiding withdrawal bleeding 1

Important caveat: The 2015 Endocrine Society guideline notes that micronized progesterone and dydrogesterone were associated with approximately 2-fold increased endometrial cancer risk when continued beyond 5 years in observational studies, though shorter-term RCTs (2-3 years) demonstrated endometrial safety 4. This discrepancy likely reflects compliance issues with separate formulations versus combined tablets.

Assisted Reproductive Technology (ART)

Dydrogesterone is effective for luteal phase support:

• Standard dose: 10 mg twice daily from oocyte retrieval until week 10 of pregnancy
• Efficacy: Comparable ongoing pregnancy rates to vaginal progesterone gel (30.3% vs 28.1%) 5
• Patient preference: Significantly higher satisfaction and tolerability than vaginal progesterone, with less vaginal bleeding, discharge, and interference with intercourse 5

Recent evidence suggests oral dydrogesterone may rescue outcomes when serum progesterone is <10 µg/L on transfer day in natural-cycle frozen embryo transfer 6.

Pregnancy-Related Conditions

• Threatened or recurrent miscarriage: Prospective trials and meta-analyses demonstrate improved pregnancy outcomes 7
• Preterm birth prevention: A 2026 meta-analysis found no statistically significant benefit over placebo (mean difference 0.42 weeks gestational age; 95% CI -0.70 to 1.55), with very low certainty evidence 8

Menstrual Disorders

• Dysmenorrhea: Significant reduction in total dysmenorrhea score (-1.84 from baseline, P<0.001) with 5 mg twice daily for 21 days per cycle 3
• Irregular cycles, premenstrual syndrome: Effective based on clinical experience 2

Dosing Regimens

For HRT (with estrogen):

• Sequential: 10 mg daily for 12-14 days per 28-day cycle
• Continuous: 5 mg daily without interruption
• Combined formulations: 1-2 mg estradiol + 5 mg dydrogesterone (continuous) or 10 mg (sequential) 1

For ART luteal support:

• 10 mg twice daily from oocyte retrieval until pregnancy test (or week 10 if pregnant) 5

For dysmenorrhea:

• 5 mg twice daily for 21 days (days 5-25 of menstrual cycle) 3

Real-world patterns:

• 20 mg sustained-release: Once daily for average 55.5 days
• 30 mg sustained-release: Once daily for average 79.7 days 9

Contraindications and Precautions

While specific contraindications are not detailed in the provided evidence, standard progestogen precautions apply:

• Active thromboembolism
• Known or suspected breast cancer (context-dependent)
• Undiagnosed vaginal bleeding
• Severe hepatic dysfunction

Critical safety concern: A 2025 WHO pharmacovigilance analysis found significantly increased reporting of birth defects with dydrogesterone, particularly hypospadias and congenital heart defects, compared to progesterone (ROR 5.4,95% CI 3.7-7.9) 10. This represents a possible safety signal requiring urgent investigation, though causality remains unestablished.

Side Effects

Common (from dysmenorrhea trial):

• Metrorrhagia (most common, 31.8% incidence of adverse drug reactions overall) 3
• Generally well-tolerated with favorable safety profile

Advantages over vaginal progesterone:

• Less vaginal bleeding, irritation, and discharge
• No interference with sexual activity
• Higher patient satisfaction 5

Metabolic profile:

Dydrogesterone demonstrates neutral effects on:

• Cardiovascular risk markers
• Blood pressure
• Thrombotic risk (favorable compared to synthetic progestogens) 1

Avoid in hypoandrogenism: Progestogens with anti-androgenic effects should be avoided in women with low testosterone, as they may worsen sexual dysfunction 1.

Clinical Decision Algorithm

For HRT in women with intact uterus:

1. First choice: Micronized progesterone (lower cardiovascular/thrombotic risk)
2. Second choice: Dydrogesterone 10 mg for 12-14 days/month (sequential) or 5 mg daily (continuous)
3. Avoid use beyond 5 years without careful risk-benefit reassessment 4, 1

For ART luteal support:

1. Offer dydrogesterone 10 mg twice daily as alternative to vaginal progesterone
2. Particularly suitable for women preferring oral route or experiencing vaginal side effects
3. Consider rescue therapy if progesterone <10 µg/L on transfer day 5, 6

For threatened miscarriage:

1. Dydrogesterone is effective and may be offered
2. Counsel regarding uncertain fetal safety signal pending further investigation 7, 10

For preterm birth prevention:

1. Do not use - insufficient evidence of benefit 8

Key Pitfalls to Avoid

1. Duration in HRT: Do not continue dydrogesterone beyond 5 years without reassessing endometrial cancer risk 4
2. Fetal safety: Counsel patients about emerging safety signal regarding birth defects, particularly when used in early pregnancy 10
3. Not for preterm birth: Despite historical use, current evidence does not support this indication 8
4. Patient selection: Avoid in women with hypoandrogenism if anti-androgenic effects are concern 1
5. Compliance: Combined estrogen-dydrogesterone formulations show better endometrial safety than separate administration, likely due to improved adherence 4