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Prometrium Post-Bariatric Surgery Use: What Clinicians and Patients Need to Know

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At a glance

  • Drug / Prometrium, oral micronized progesterone 100 mg and 200 mg capsules [1]
  • Labeled uses / Endometrial hyperplasia prevention with conjugated estrogens; secondary amenorrhea [1]
  • Label dose / 200 mg at bedtime, 12 days per 28-day cycle, with conjugated estrogens [1]
  • Before surgery / Label says stop 4 to 6 weeks before high-clot-risk surgery, if feasible [1][2]
  • Peanut allergy / Contraindicated; capsules contain peanut oil [1]
  • Boxed warning / None in the current 02/2026 label [3][2]

What the label says about surgery

The current Prometrium label (Revision 02/2026) says that, if feasible, the drug should be discontinued at least 4 to 6 weeks before surgery of a type associated with an increased risk of thromboembolism, or during periods of prolonged immobilization [1][2]. Active DVT or pulmonary embolism, a history of either, active arterial thromboembolic disease such as stroke or heart attack, and a history of these are contraindications [1]. The two approved uses, endometrial hyperplasia prevention in postmenopausal women with a uterus who take conjugated estrogens tablets and secondary amenorrhea, do not list bariatric procedures [1].

What the label reports about absorption

Serum concentrations peak within 3 hours of an oral dose [2]. After five daily doses in postmenopausal women, mean Cmax was 17.3 ng/mL at 100 mg and 38.1 ng/mL at 200 mg, with standard deviations often larger than the means [2]. Levels were dose proportional from 100 to 300 mg/day [2]. The label states that absolute bioavailability is not known, that food increased bioavailability relative to fasting at a 200 mg dose without giving the size of the increase, and that pharmacokinetics have not been assessed in obese patients [2].

Endometrial protection with oral dosing

In the label's endometrial trial, 358 postmenopausal women with a uterus were treated for up to 36 months. Hyperplasia occurred in 6% (7 of 117) of women taking Prometrium 200 mg for 12 days per 28-day cycle with conjugated estrogens 0.625 mg, 64% (74 of 115) of those taking conjugated estrogens alone, and 3% (3 of 116) of those taking placebo; atypical hyperplasia occurred in 1%, 12% and 0% [2]. The trial used conjugated estrogens, not estradiol [2].

Other Prometrium safety information

Peanut allergy is a labeled contraindication, not a caution: the capsules contain peanut oil [1]. The label says Prometrium may cause transient dizziness and drowsiness, should be used with caution when driving or operating machinery, and should be taken as a single daily dose at bedtime [1][2].

The current 02/2026 label has no boxed warning; FDA approved removal of the cardiovascular, breast cancer and probable dementia boxed-warning language from six menopausal hormone products on 2026-02-12, and Prometrium was one of them [3][4].

Frequently asked questions

Does bariatric surgery change how oral Prometrium is absorbed?
The label gives no bariatric-specific absorption data. It states that absolute bioavailability is not known and that pharmacokinetics have not been assessed in obese patients [2].
Is bariatric surgery a contraindication to Prometrium?
It is not one of the label's six contraindications: peanut or ingredient allergy, unexplained genital bleeding, known or suspected breast cancer or a history of it, active or prior DVT or pulmonary embolism, active or prior arterial thromboembolic disease, and known liver dysfunction or disease [1].
What does the label say about stopping Prometrium before an operation?
The Prometrium label says that, if feasible, the drug should be discontinued at least 4 to 6 weeks before surgery of a type associated with increased thromboembolism risk, or during prolonged immobilization [1][2].
Can Prometrium capsules be used vaginally?
The label covers oral capsules only [1]. Vaginal progesterone has been studied as a 90 mg gel rather than as Prometrium capsules: in 14 postmenopausal women having hysterectomy, the median ratio of endometrial to serum progesterone concentration (x 100) was 14.1 with the vaginal gel versus 1.2 with intramuscular progesterone 50 mg [5].

References

  1. U.S. National Library of Medicine, DailyMed. Prometrium progesterone capsules (Acertis), Rev. 02/2026 prescribing information. Prometrium progesterone capsules (Acertis), Rev. 02/2026 label
  2. U.S. Food and Drug Administration. U.S. Food and Drug Administration
  3. FDA Approves Labeling Changes to Menopausal Hormone Therapy Products | FDA. FDA Approves Labeling Changes to Menopausal Hormone Therapy Products | FDA
  4. Menopausal Hormone Therapies with Updated Prescribing Information | FDA. Menopausal Hormone Therapies with Updated Prescribing Information | FDA
  5. Cicinelli E, de Ziegler D, Bulletti C, Matteo MG, Schonauer LM, Galantino P. Direct transport of progesterone from vagina to uterus. Obstet Gynecol. 2000;95(3):403-6. Direct transport of progesterone from vagina to uterus
Evidence overview for Prometrium Post-Bariatric Surgery Use: What Clinicians and Patients Need to Know