What Are Examples of Bioidentical Progesterone?

October 9, 2025 •

4 min read

Bioidentical progesterone is chemically and structurally identical to the progesterone naturally produced by the human body. For those exploring hormone replacement options, understanding what are examples of bioidentical progesterone is crucial for making informed health decisions with a physician.

Quick Summary

Examples of bioidentical progesterone include FDA-approved oral capsules like Prometrium and various customized formulations from compounding pharmacies. These differ from synthetic progestins in chemical structure and regulatory oversight.

Key Points

FDA-Approved Options: Prometrium (oral capsules) is a well-known example of FDA-approved bioidentical micronized progesterone.
Compounded Preparations: Compounding pharmacies create custom bioidentical progesterone formulations in various strengths and delivery methods, like creams and capsules.
Lack of Regulation for Compounded Hormones: Unlike FDA-approved versions, compounded bioidentical hormones are not regulated for consistency, purity, or potency.
Bioidentical vs. Synthetic: Bioidentical progesterone is chemically identical to the body's own hormone, while synthetic progestins (like Provera) have a different molecular structure and potentially different effects.
Varied Delivery Methods: Bioidentical progesterone can be administered through oral capsules, topical creams or gels, and vaginal inserts.
Professional Guidance: It is crucial to discuss bioidentical progesterone options with a healthcare provider to determine the most appropriate and safest treatment plan.

Bioidentical hormones are molecules that are structurally identical to the hormones produced by the body, offering a precise mimicry of natural hormonal function. In contrast, synthetic hormones are chemically altered versions of the body's hormones, which can lead to different physiological effects and side effect profiles. When considering bioidentical progesterone for hormone replacement therapy (HRT), it is essential to distinguish between FDA-approved pharmaceutical products and custom-compounded preparations, as they differ in regulation, consistency, and manufacturing standards. This distinction is critical for patient safety and treatment efficacy.

FDA-Approved Examples of Bioidentical Progesterone

The FDA regulates and approves specific pharmaceutical products that contain bioidentical progesterone, ensuring their safety, purity, and potency. These products offer consistent dosages and are often covered by insurance, making them a standard and accessible option for many patients. These examples are derived from plant sources but are chemically converted in a lab to be structurally identical to human progesterone.

Oral Capsules

Prometrium (micronized progesterone): This is perhaps the most widely known FDA-approved bioidentical progesterone product, available as 100 mg and 200 mg oral capsules. It is often prescribed for postmenopausal women taking estrogen to protect the uterine lining from overgrowth (endometrial hyperplasia). It is also used to treat irregular menstrual cycles in non-menopausal individuals. Prometrium is micronized (finely ground) to improve absorption and is suspended in peanut oil, which is a consideration for those with allergies.
Generic Micronized Progesterone: A generic version of Prometrium is also available, offering a more affordable alternative while providing the same regulated bioidentical progesterone.
Combination Products (e.g., Bijuva): Some FDA-approved products combine bioidentical estradiol with bioidentical progesterone in a single oral capsule. Bijuva is one such example approved for treating moderate to severe hot flashes associated with menopause.

Vaginal Preparations

Crinone (progesterone gel): This is an FDA-approved bioidentical progesterone vaginal gel used for women undergoing fertility treatments and to prevent pregnancy complications in certain cases.
Endometrin (progesterone insert): A vaginal insert containing bioidentical progesterone, often prescribed for similar fertility-related purposes as Crinone.

Compounded Bioidentical Progesterone

Compounding pharmacies can create custom bioidentical hormone preparations based on a practitioner's prescription. These formulations are attractive to patients who need specific dosages, delivery methods, or have sensitivities to ingredients in standard products (e.g., peanut oil in Prometrium). However, it is important to understand that these preparations are not regulated or approved by the FDA, which means their quality, potency, and purity can vary.

Common Compounded Forms

Topical Creams and Gels: Progesterone can be compounded into creams or gels for transdermal application, which some believe offers a more stable absorption profile than oral medications. However, studies on the effectiveness and absorption consistency of these over-the-counter and compounded creams are limited.
Sublingual Lozenges: Also known as troches, these are designed to dissolve under the tongue, allowing for direct absorption into the bloodstream.
Vaginal Suppositories: Often used in fertility treatments or for localized uterine effects.
Custom Capsules: For patients who require a specific dosage not available in standard FDA-approved strengths, compounding pharmacies can create customized oral capsules.

Bioidentical vs. Synthetic Progestins

It is crucial to differentiate bioidentical progesterone from synthetic progestins (e.g., medroxyprogesterone acetate or MPA, sold as Provera), which were used in earlier studies like the Women's Health Initiative. While both bind to progesterone receptors, their different chemical structures can lead to distinct physiological actions and side effects. For example, some studies suggest bioidentical progesterone may have a different, potentially more favorable, risk profile regarding breast cancer and cardiovascular health compared to synthetic progestins, though more research is ongoing.

Comparison of FDA-Approved vs. Compounded Bioidentical Progesterone


Feature	FDA-Approved Bioidentical Progesterone	Compounded Bioidentical Progesterone
Regulation & Oversight	Regulated by the FDA for safety, quality, and efficacy.	Not regulated or approved by the FDA.
Potency & Purity	Consistent and verified by the FDA through strict manufacturing standards.	Potency and purity can vary between batches and pharmacies.
Dosage & Ingredients	Standardized dosages and ingredients (e.g., peanut oil in Prometrium).	Customizable dosages and ingredients to meet specific patient needs.
Routes of Administration	Oral capsules, vaginal gels, and vaginal inserts.	A wider variety, including creams, gels, lotions, sublingual lozenges, and suppositories.
Side Effects	Established side effect profile based on clinical trials.	Potential for inconsistent side effects due to varying formulations.
Scientific Evidence	Supported by randomized, controlled clinical trials.	Limited high-quality data from large-scale, controlled trials.
Cost & Insurance	Often covered by insurance, with established pricing.	Typically not covered by insurance and can be more expensive.

Conclusion

Bioidentical progesterone is available in both standardized, FDA-approved forms and customized compounded preparations. The primary FDA-approved example is oral micronized progesterone (Prometrium and its generic), which is often used in combination with estrogen therapy to protect the uterine lining. Other regulated options include vaginal gels and inserts like Crinone and Endometrin. In contrast, compounded versions offer a wider range of dosage forms and customization but lack the FDA's regulatory oversight, leading to concerns about consistency and quality. Patients and healthcare providers should be aware of these differences, as well as the important distinction between bioidentical progesterone and synthetic progestins, which have differing risk profiles. Ultimately, the decision to use any form of bioidentical progesterone should be made in consultation with a qualified healthcare professional who can weigh the specific benefits and risks for the individual patient.

For more information on compounded bioidentical menopausal hormone therapy, refer to the guidance from the American College of Obstetricians and Gynecologists: Compounded Bioidentical Menopausal Hormone Therapy.

Frequently Asked Questions

Bioidentical progesterone has the exact same molecular structure as the progesterone produced naturally by the body. Synthetic progestins, such as medroxyprogesterone acetate (Provera), have a modified chemical structure that allows them to mimic some progesterone effects but can have different physiological actions and side effects.

Yes, Prometrium is an FDA-approved brand of bioidentical micronized progesterone. It is available as oral capsules and is derived from plant sources before being processed to be chemically identical to the body's hormone.

No, compounded bioidentical progesterone creams and gels are not regulated or approved by the FDA. While compounding pharmacies can create custom formulations, their purity and potency are not standardized, unlike commercial FDA-approved products.

Side effects can vary by product and individual, but oral micronized progesterone (Prometrium) may cause drowsiness or fatigue, which is why it is often taken at bedtime. Other possible side effects include headaches, weight changes, or breast tenderness.

While some low-potency progesterone creams can be found over-the-counter, they are not regulated and are generally not as effective as prescription options for systemic absorption or protecting the uterine lining. Prescription bioidentical progesterone, like Prometrium, is required for therapeutic use.

For fertility treatments, bioidentical progesterone is often administered via vaginal preparations, such as gels (Crinone) or inserts (Endometrin). These provide localized support to the uterine lining and are often preferred over oral capsules in these cases.

Some observational studies suggest that bioidentical progesterone may have a more favorable safety profile regarding breast cancer and cardiovascular risks compared to synthetic progestins, particularly medroxyprogesterone acetate (MPA). However, the data is complex, and ongoing research is necessary to fully understand the long-term safety differences.