Progesterone 100 mg (14 tablets) - Indications and Prescribing
A prescription for progesterone 100 mg for 14 tablets is most commonly used as part of sequential hormone replacement therapy (HRT) in women with premature ovarian insufficiency or menopause, where it provides endometrial protection when combined with continuous estrogen therapy. 1
Primary Clinical Indication
Hormone Replacement Therapy - Sequential Regimen
The standard protocol involves taking 100 mg of oral micronized progesterone (MP) daily for 12-14 days every 28-day cycle, combined with continuous transdermal or oral estrogen. 1 This 14-tablet prescription represents one cycle of progestin therapy.
Specific Dosing Protocol:
- Dose: 100 mg oral micronized progesterone daily
- Duration: 12-14 consecutive days per 28-day cycle
- Timing: Typically days 15-28 of the cycle (or last 12-14 days)
- Administration: Take at bedtime to minimize drowsiness 2, 3
- Concurrent therapy: Continuous estrogen (transdermal patches 50 μg daily or oral 1-2 mg daily) 1
Why This Specific Regimen
Endometrial Protection
The primary purpose is preventing estrogen-induced endometrial hyperplasia and adenocarcinoma in non-hysterectomized women receiving estrogen therapy. 1 Sequential administration of 100 mg MP for 12-14 days provides adequate endometrial protection by:
- Fully inhibiting mitoses in endometrial tissue 3
- Inducing secretory transformation
- Preventing hyperplasia (0% incidence in studies) 3
Withdrawal Bleeding Pattern
This sequential regimen induces predictable withdrawal bleeding, which occurs after completing the 14-day progesterone course. 1 This is appropriate for women who:
- Accept monthly withdrawal bleeding
- Want early pregnancy detection (absence of bleeding prompts pregnancy testing) 1
- Prefer a more "natural" cycle pattern
Alternative Indications (Less Common for 14-Tablet Prescription)
While less typical for exactly 14 tablets, progesterone 100 mg may also be prescribed for:
Diagnostic Challenge Test
- Single dose or short course to assess endometrial responsiveness in amenorrhea evaluation 4
- Not the standard 14-day protocol
Luteal Phase Support
Clinical Context: Who Receives This Prescription
Primary Population
- Post-pubertal adolescents and young women with iatrogenic premature ovarian insufficiency (POI) from chemotherapy/radiation 1
- Perimenopausal and menopausal women requiring HRT 2, 3, 6
- Women with spontaneous POI needing hormone replacement 1, 5
Key Requirement
Must have an intact uterus - women who have undergone hysterectomy do not require progesterone therapy. 1
Why Micronized Progesterone 100 mg is Preferred
Micronized progesterone (MP) is the first-choice progestin due to its superior safety profile compared to synthetic progestins: 1
- Lower cardiovascular risk - neutral/beneficial effects on blood pressure 1
- Better thrombotic safety profile - lowest venous thromboembolism risk among progestogens 1
- Metabolic advantages - minimal negative impact on lipid profiles 1, 2
- Neurosteroid benefits - may improve sleep and reduce anxiety when taken at bedtime 4
Important Prescribing Considerations
Dosing Alternatives
If 100 mg daily for 12-14 days is insufficient for endometrial protection (rare), alternatives include:
- 200 mg daily for 12-14 days (higher dose sequential) 1
- 100 mg daily for 25 days/month (near-continuous, induces amenorrhea) 3
Common Side Effects
- Mild drowsiness/somnolence (41.6% vs 19.7% placebo) - minimized by bedtime dosing 7, 8
- Dizziness (29.1% vs 9.8% placebo) 7, 8
- Vaginal dryness (20.8% vs 8.7% placebo) 7
Critical Safety Points
- Contains peanut oil - contraindicated in peanut allergy 9
- Food increases bioavailability - consistent timing with/without food recommended 9
- CYP3A4 interactions - ketoconazole and similar inhibitors may increase progesterone levels 9
When NOT to Use This Regimen
Do not prescribe progesterone if:
- Patient has undergone hysterectomy (no endometrium to protect)
- Contraception is the primary goal (use combined oral contraceptives instead) 1
- Patient desires continuous amenorrhea (use continuous combined regimen instead) 1
- History of breast cancer (generally contraindicated) 5
Clinical Pearl
The 14-tablet prescription specifically indicates sequential HRT with planned withdrawal bleeding. If the goal were continuous therapy to avoid bleeding, the prescription would be for 25-28 tablets per month at 100 mg daily. 3 The 14-day duration is the minimum required for adequate endometrial protection when combined with full-dose estrogen replacement. 1