Prometrium is a bioidentical progesterone capsule indicated for use in hormone replacement therapy (HRT) and the management of secondary amenorrhea. As a micronized, oral formulation of natural progesterone, it is structurally identical to the hormone produced by the human corpus luteum. This product is designed to support endometrial protection, regulate menstrual cycles, and mitigate symptoms of progesterone deficiency in appropriately indicated patients. Its evidence-based formulation offers a critical therapeutic option for clinicians managing hormonal imbalances.

Features

• Contains 100 mg or 200 mg micronized progesterone per soft gelatin capsule
• Bioidentical to endogenous human progesterone
• Oral administration with peak plasma concentrations achieved within ~3 hours
• Formulated in peanut oil; capsules should not be used in patients with peanut allergies
• Available in sealed, light-resistant bottles to maintain stability

Benefits

• Provides endometrial protection against unopposed estrogen in postmenopausal women with a uterus
• Helps restore regular menstrual cycles in women with secondary amenorrhea
• Reduces the frequency and severity of vasomotor symptoms in perimenopausal and postmenopausal patients
• Supports luteal phase supplementation in assisted reproductive technology (ART) protocols
• May improve sleep quality and mood stability in some individuals with progesterone deficiency
• Offers a natural hormone option with a well-characterized metabolic profile

Common use

Prometrium is commonly prescribed as part of combination hormone replacement therapy in postmenopausal women with an intact uterus to prevent endometrial hyperplasia. It is also used to treat secondary amenorrhea and to support the luteal phase in fertility treatments. Off-label uses may include management of premenstrual dysphoric disorder (PMDD) and prevention of preterm birth in certain high-risk obstetric cases, though these are not FDA-approved indications.

Dosage and direction

For secondary amenorrhea: 400 mg orally once daily at bedtime for 10 days.
For postmenopausal HRT (with estrogen): 200 mg orally once daily at bedtime for 12 sequential days per 28-day cycle.
Administration at bedtime is recommended to minimize dizziness and drowsiness. Capsules should be swallowed whole; not to be crushed, chewed, or broken. Dosage adjustments may be necessary based on individual patient response, hepatic function, and concomitant medications.

Precautions

Patients should be advised that Prometrium may cause dizziness, drowsiness, or blurred vision. Alcohol and CNS depressants may potentiate these effects. Use with caution in patients with depression, diabetes, cardiovascular disease, or renal impairment. Regular monitoring of liver function is advised during prolonged therapy. Prometrium may cause fluid retention; caution is warranted in patients with conditions that might be influenced by this factor (e.g., epilepsy, migraine, asthma, cardiac or renal dysfunction).

Contraindications

Prometrium is contraindicated in patients with known hypersensitivity to progesterone, peanut oil, or any component of the formulation. Other contraindications include: known or suspected breast or genital malignancies, undiagnosed abnormal genital bleeding, history of or active thrombophlebitis or thromboembolic disorders, missed abortion, severe hepatic dysfunction, and known or suspected pregnancy (except as part of ART under specialist supervision).

Possible side effects

Common side effects (>10%) include: drowsiness, dizziness, breast tenderness, headache.
Less common side effects (1–10%) include: bloating, mood swings, nausea, hot flashes, fatigue.
Rare but serious side effects (<1%) require immediate medical attention: sudden vision changes, severe depressive symptoms, signs of thrombophlebitis (pain, swelling, warmth in limbs), jaundice, severe abdominal pain, allergic reactions. Patients should report any unusual symptoms promptly.

Drug interaction

Prometrium may interact with:

• CYP3A4 inducers (e.g., carbamazepine, rifampin) – may decrease progesterone levels
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) – may increase progesterone levels and side effects
• Other hormonal therapies – may alter overall hormonal balance
• CNS depressants (e.g., benzodiazepines, opioids) – additive sedative effects
• Anticoagulants – may diminish anticoagulant effect
  A comprehensive medication review is essential before initiation.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is almost time for the next dose. Doubling doses to make up for a missed dose is not recommended. Patients should maintain regular dosing schedules and contact their healthcare provider if multiple doses are missed or if uncertainty exists about proper administration.

Overdose

Acute overdose may exacerbate common side effects, particularly severe drowsiness, dizziness, and nausea. There is no specific antidote; treatment should be symptomatic and supportive. Gastric lavage may be considered if ingestion was recent. Medical attention should be sought immediately in cases of suspected overdose, especially if respiratory depression occurs.

Storage

Store at controlled room temperature (20–25°C or 68–77°F). Excursions permitted to 15–30°C (59–86°F). Keep container tightly closed and protected from light and moisture. Do not freeze. Keep out of reach of children and pets. Do not use after expiration date printed on packaging.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or stopping any medication. Individual patient needs may vary based on health status, concomitant conditions, and other factors. Only a licensed medical professional can determine appropriate therapy.

Reviews

Clinical studies and patient reports generally indicate good tolerance and efficacy when Prometrium is used as directed under medical supervision. Many patients appreciate its natural hormone profile compared to synthetic progestins. Some note improved sleep and reduced perimenopausal symptoms. Criticisms occasionally include sedation and bloating. Overall, it remains a well-regarded option in progesterone replacement therapy when appropriately prescribed.