Progest

Progesterone

Method of action: Endocrine Therapy, Gestagenic, Sex Hormones And Modulators Of The Genital System

Treatment option: Abortion, Infertility, Menopause And Perimenopause, Menstrual Disorders, Premenstrual Syndrome, Endometriosis

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Progest

Understanding Progest

Progest is a pharmaceutical formulation of progesterone, a naturally occurring steroid hormone that plays a fundamental role in the human reproductive system. It is classified as a progestogen and is chemically identical to the hormone produced by the ovaries during the menstrual cycle and by the placenta during pregnancy.

Biological Role of Progesterone

In the body, progesterone is responsible for preparing and maintaining the uterine environment. Its primary functions include:

Endometrial Regulation: It transforms the uterine lining (endometrium) from a proliferative state to a secretory state, making it receptive to the implantation of a fertilized egg.
Pregnancy Support: If conception occurs, progesterone helps maintain the pregnancy by suppressing uterine contractions and supporting the development of the placenta.
Hormonal Balance: It acts in coordination with estrogen to regulate the monthly menstrual cycle.

Therapeutic Applications

Progest is utilized in various clinical settings to address conditions associated with progesterone deficiency or hormonal imbalance.

Hormone Replacement Therapy

For individuals undergoing menopause, Progest is often used in combination with estrogen. While estrogen helps manage menopausal symptoms, progesterone is included to protect the uterine lining from overgrowth, which can occur when estrogen is used alone.

Reproductive Support

In the context of assisted reproductive technology and fertility treatments, Progest may be used to support the luteal phase. This ensures the uterine environment remains stable enough to support early embryo development and attachment.

Menstrual Regulation

The medication may also be used to treat secondary amenorrhea (the absence of periods) or abnormal uterine bleeding caused by hormonal fluctuations. By providing a controlled source of progesterone, it helps re-establish a more regular shedding of the endometrial lining.

Regulatory References

Progesterone: MedlinePlus Drug Information

What side effects are possible with Progest?

Possible Side Effects and Safety Information

The safety profile for Progest (micronized progesterone) is officially documented by regulatory authorities, with adverse reactions categorized by their frequency and the body system affected. These classifications reflect how government regulatory documents organize and communicate the medicine’s safety profile.

Common adverse reactions, occurring in at least 1 out of 100 people, typically include dizziness, somnolence (drowsiness), headache, nausea, abdominal pain, and breast tenderness. Drowsiness is particularly noted with oral administration and is often transient, being more common at the beginning of treatment. Uncommon reactions, affecting less than 1 in 100 people, can involve mood changes, such as depression, and certain non-severe, reversible liver disorders.

Serious Adverse Reactions and Safety Constraints

Official labeling highlights critical safety concerns, particularly when Progest is used in combination with estrogen for postmenopausal hormone therapy. These serious adverse reactions include an increased risk of arterial and venous thromboembolic events (e.g., stroke, pulmonary embolism, deep vein thrombosis) and an increased risk of invasive breast cancer. For women aged 65 and older on combined therapy, there is a specific safety note regarding an increased risk of probable dementia.

Population-Specific Constraints: The medication is contraindicated in individuals with severe active liver disease or impairment. Furthermore, the label requires caution in patients with conditions that may be exacerbated by fluid retention, such as epilepsy, asthma, and migraine. Discontinuation of Progest is required if severe events like jaundice, new thromboembolic events, or visual disturbances develop.

Overdose and Emergency Response

Overdose and when to seek help

The official regulatory profile for Progest overdose details the documented signs of overexposure and mandates specific emergency actions, as established in government prescribing information.

Documented Clinical Manifestations Overdose may present with central nervous system effects such as somnolence (drowsiness) and dizziness. Gastrointestinal symptoms like severe nausea and vomiting are also documented, alongside fatigue, headache, abdominal pain, and potentially vaginal haemorrhage. These manifestations, particularly CNS effects, guide the initial regulatory classification of overexposure.

Severe Outcomes and Required Emergency Action Symptoms indicating a potentially life-threatening event require immediate medical intervention. These severe outcomes include seizure, collapse, trouble breathing, or the inability to be awakened (loss of consciousness). For these urgent manifestations, emergency services (911) must be contacted immediately. For any other suspected overexposure, professional guidance should be sought by contacting a poison control center or emergency room at once, as required by official guidance.

Overdose Management The established treatment approach is the discontinuation of the drug. Supportive care measures are required, as no specific antidote for micronized progesterone is known to be available. Management focuses on providing appropriate symptomatic and supportive care as necessary for the clinical presentation, as described in regulatory documentation.

Therapeutic Uses of Progest

Main Uses and Therapeutic Applications

Progest is a hormonal medication containing micronized progesterone, which is identical in structure to the hormone naturally produced by the human body. It is primarily used to address conditions arising from a deficiency in natural progesterone levels.

Hormone Replacement Therapy

One of the primary applications of Progest is in hormone replacement therapy for women reaching menopause. In this context, it is used to protect the uterine lining. When estrogen is administered alone, it can cause the lining of the uterus to thicken excessively; Progest helps maintain a healthy balance, reducing the risks associated with estrogen-only therapy.

Menstrual Cycle Regulation

Progest is utilized to treat various menstrual irregularities. It is often prescribed for secondary amenorrhea, a condition where menstrual periods have stopped for several months in women who previously had regular cycles. By providing the necessary hormonal support, it helps re-establish a more predictable menstrual pattern.

Support for Reproductive Health

In specific clinical settings, Progest is used to support the early stages of pregnancy. It helps prepare and maintain the lining of the uterus to facilitate the implantation of an embryo and supports the pregnancy during the first trimester when the body may not be producing sufficient progesterone on its own.

Key Benefits

Hormonal Balance: Helps restore physiological levels of progesterone in the body.
Endometrial Protection: Acts as a stabilizing agent for the uterine lining during estrogen therapy.
Versatility of Use: Can be used for both systemic concerns related to menopause and specific reproductive health requirements.
Bio-identical Composition: Because it is micronized progesterone, the body processes it in a manner similar to endogenous hormones.

Regulatory References

NIH MedlinePlus overview

Eligibility and Restrictions for Use

Progest (Micronized Progesterone) is governed by official regulatory criteria that strictly define who is eligible to use the medicine based on absolute prohibitions and specific restrictions.

Absolute Contraindications

Use of Progest is absolutely contraindicated in patients with certain high-risk medical conditions. These include known or suspected malignancy of the breast or other hormone-dependent tumours, severe hepatic disease or dysfunction, and undiagnosed abnormal genital bleeding. The medicine must also not be used by individuals with active arterial or venous thromboembolism or a history of these events, such as a stroke or deep vein thrombosis. Use is also prohibited if there is a known hypersensitivity to progesterone or any component of the formulation.

Restricted and Age-Related Use

For patients with mild to moderate hepatic dysfunction or renal insufficiency, use is allowed but requires caution and close monitoring. The medicine is not established for use in pediatric patients (children and adolescents). In geriatric patients 65 years and older, the use of estrogen plus progestin therapy is associated with an increased risk of probable dementia.

Pregnancy and Lactation Status

Eligibility during pregnancy is indication-specific: Progest is a reason for immediate withdrawal if pregnancy occurs during use for Menopausal Hormone Therapy, but it is indicated and permitted for luteal phase support in Assisted Reproductive Technology (ART). Use is not recommended while breastfeeding.

What should I know about interactions with other medicines?

Progest Interactions with other medicines and products

Official regulatory documents describe several interaction patterns for Progest (micronized progesterone), primarily involving changes to its metabolism and effects on other medications.

Documented Metabolic Interactions

Interactions often center on the Cytochrome P450 3A4 (CYP3A4) enzyme in the liver. Products that induce (increase the activity of) CYP3A4, such as rifampicin, phenytoin, and carbamazepine, may increase the clearance of Progest, potentially reducing its systemic exposure. Conversely, strong inhibitors of CYP3A4, such as ketoconazole, are expected to decrease clearance, leading to potentially increased plasma levels of Progest.

Exposure and Pharmacodynamic Effects

Progest may influence the plasma concentrations of certain co-administered drugs. Regulatory labeling indicates that Progest may raise the plasma concentration of ciclosporin and tizanidine. In addition, a pharmacodynamic interaction exists with anti-diabetic agents, as progestins may impair glucose tolerance, requiring monitoring for changes in the need for anti-diabetic medications. The efficacy of Progest is also expected to be reduced by ulipristal acetate.

Mechanism of Action

How Progest Works: Mechanism of Action

Progest functions as an agonist by binding to and modulating the Progesterone Receptor (PR), which exists as both nuclear ( PR-A and PR-B) and membrane-associated ( mPR) isoforms. This action initiates its effects through two integrated signaling mechanisms.

The genomic mechanism involves the drug-receptor complex modulating gene transcription in the nucleus for sustained cellular changes. Simultaneously, the non-genomic mechanism involves mPR binding, leading to the rapid activation of cytoplasmic signaling cascades, such as the MAPK/ERK pathway, which quickly alters cell function, including smooth muscle tone.

Systemically, Progest exerts a negative feedback effect on the Hypothalamic-Pituitary-Ovarian ( HPO) axis, suppressing GnRH release and, subsequently, Luteinizing Hormone ( LH) and Follicle-Stimulating Hormone ( FSH). This establishes a hormonal environment characteristic of the luteal phase and impacts follicular development.

Furthermore, Progest is metabolized into neuroactive steroids, notably allopregnanolone, which acts as a positive allosteric modulator of the inhibitory GABAA receptor in the CNS. This modulation enhances inhibitory signaling, resulting in decreased spontaneous neuronal firing.

Dosage and Administration Information

How Progest is Used

Progest (micronized progesterone) is used according to established protocols intended to maintain proper dosing and therapeutic effect. The usage patterns specify both the routes of administration and the dosing schedules, which are typically cyclic rather than continuous.

Approved Routes and Core Dosing

Micronized progesterone is administered via two primary methods, depending on the specific application:

Administration Route	Standard Adult Cyclic Dose Pattern
Oral Route (Capsules)	200 mg once daily, typically for 10 to 12 consecutive days of a planned cycle, used for endometrial protection in Menopausal Hormone Therapy (MHT). A 400 mg dose for 10 consecutive days is specified for treating secondary amenorrhea.
Vaginal Route (Capsules/Inserts)	Typically 100 mg two or three times daily, or higher doses, used in specific regimens such as Luteal Phase Support (LPS) in Assisted Reproductive Technology (ART). This use may continue for up to 10–12 weeks of gestation.

Timing and Administration Conditions

Timing: Oral capsules are taken at bedtime (qHS). This specific timing is recommended to maintain consistency in the body's levels of the medication.

With or Without Food: The oral capsule is taken without food. Food intake significantly increases the bioavailability of the drug, which may affect the intended concentration in the bloodstream.

Handling: Oral capsules are swallowed whole with water. For both oral and vaginal forms, specific procedures apply for missed doses and for separating the use of other vaginal products by several hours to prevent interference with absorption.

Recent Clinical Evidence

Progest: Recent Clinical Evidence

Evidence for Endometrial Support in Hormone Therapy

Studies, including Randomized Controlled Trials (RCTs), have evaluated micronized progesterone when used alongside estrogen in postmenopausal women with an intact uterus. The primary research goal was to examine outcomes related to the uterine lining tissue. Studies monitored the histological state of the lining in populations receiving the combined regimen. Data show patterns related to the frequency of abnormal tissue changes when compared to women receiving estrogen alone. The full scope of long-term outcomes (beyond five years) as reported by prospective RCTs remains limited, with much of this data derived from observational settings.

Evidence for Luteal Phase Support in Assisted Reproductive Technology (ART)

Randomized Controlled Trials and systematic reviews have explored the use of progesterone as a supplement for women undergoing Assisted Reproductive Technology (ART) like IVF. The primary endpoints examined included rates of Live Birth (LBR) and Clinical Pregnancy (CPR). Studies monitored women receiving supplementation and research examined outcomes related to these rates as compared to control groups where permitted. High variability was noted across studies regarding administration methods, and the specific clinical advantages of different routes (e.g., oral versus vaginal) are not uniformly established.

Evidence for Cycle Regulation

Short-term Clinical Trials have focused on women of reproductive age experiencing secondary amenorrhea (missed periods) who have adequate estrogen levels. The primary outcome studied was the occurrence of withdrawal bleeding following a short course of treatment. Findings indicate a highly consistent pattern where the majority of estrogenized women observed in the research reported this short-term outcome. Data on using progesterone for this indication across various specific patient subgroups are limited, and long-term cycle patterns are not well established by this research.

Research Gaps and Follow-Up

The research landscape includes short-term RCTs and longer-term observational studies. Research has explored short-term outcomes through RCTs, but the full scope of outcomes over many years relies primarily on data extracted from larger observational cohorts. Comparative evidence is lacking in some areas, particularly concerning long-term, head-to-head large-scale RCTs against all synthetic progestins. Data for certain groups, such as those with comorbidities, remain insufficient in the primary research.

Key Studies & References

Frequently Asked Questions (FAQ)

Common questions about Progest (FAQ)

Q: Are there generic versions of Progest available?

Yes, Progest contains the active ingredient micronized progesterone. Official regulatory documents and patient information indicate that micronized progesterone is also available from various manufacturers as a generic prescription capsule. This means that both brand-name and generic options are available.

Q: Can you take Progest while drinking alcohol?

Official product information notes that alcohol is one of the substances that may have an interaction with Progest. Patients should discuss alcohol consumption with their healthcare provider to determine the appropriate course of action.

Q: Can Progest be taken if I have high blood pressure?

Regulatory warnings mention that Progest can cause fluid retention in some patients, which may affect underlying conditions. A healthcare provider must be informed of pre-existing high blood pressure, as close monitoring may be required during the course of treatment.

Q: Can Progest be used for conditions not related to hormones?

The official regulatory-defined uses for Progest are for hormonal support. This includes helping to protect the uterine lining during Menopausal Hormone Therapy (MHT) and supporting the luteal phase in Assisted Reproductive Technology (ART). Its approved indications are defined strictly within the scope of these hormone-related conditions.

Q: Does Progest have any effect on bone density?

While Progest is not officially indicated for conditions like osteoporosis, some clinical research suggests that progesterone, especially when used alongside estrogen in hormone therapy, may contribute positively to bone mineral density. Any assessment of individual risk and bone health should be conducted by a healthcare provider.

Q: Is hair loss a possible side effect of Progest?

Some regulatory-sourced documents and post-marketing reports indicate that hair loss or thinning of the hair has been observed as a less common side effect. Patients are advised to consult their healthcare provider if they experience concerning changes in their hair while taking Progest.

Q: Is it safe to drive or operate machinery while on Progest?

Because Progest can cause dizziness or drowsiness, product labeling includes a warning advising caution when performing tasks like driving or operating machinery. Users should wait until they know how the medication affects them before engaging in these activities.

Q: Can men ever be prescribed Progest, and for what condition?

The official regulatory labels primarily detail the use of Progest for women’s health conditions (MHT, ART, and amenorrhea). The product is not officially approved for general use in men, although pharmacokinetic studies have been conducted in male volunteers.

Q: Does Progest affect cholesterol levels?

Regulatory-cited research indicates that micronized progesterone often has a more neutral profile regarding lipid and cholesterol levels compared to some older, synthetic progestins. Any monitoring of the lipid profile should be conducted by a healthcare provider.

Q: Are there any known interactions between Progest and antidepressant medications?

Progest can cause central nervous system (CNS) effects like depression and mood changes, which may be relevant when combined with antidepressants. The combination of Progest and antidepressant medications requires a thorough evaluation and ongoing monitoring by a healthcare provider.

How should Progest be stored and disposed of?

How to Store and Dispose of Progest?

The storage and handling of Progest (micronized progesterone) must strictly adhere to regulatory requirements to maintain product stability and quality.

Storage Conditions

Progest capsules must be stored at Controlled Room Temperature (CRT), typically maintained between 20 C and 25 C (68 F and 77 F). The medicine must be protected from excessive heat and moisture; therefore, storage in environments like the bathroom is prohibited. The product should remain in its original, tightly closed container until use. Storage must always be out of the sight and reach of children.

Disposal Instructions

Unused or expired Progest must be disposed of according to local pharmaceutical waste requirements. It is officially mandated not to flush the medication down a toilet or pour it into a drain to prevent environmental contamination.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.