Nogest

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Nogest

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Medically reviewed

Rosario Oropesa

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 Nogest

What is Nogest? Defining the Core Entity

Property Description
Active ingredient Nomegestrol acetate
Form Oral tablet (Film-coated)
Pharmacological class Synthetic Progestogen / Hormonal Agent
Common use Hormonal Regulation / Contraception
Origin Synthetic (19-norprogesterone derivative)

Nomegestrol acetate (Nogest) is a synthetic progestogen and a highly selective hormonal agent used primarily for hormonal regulation within the female reproductive system. The active component, Nomegestrol acetate (NOMAC), is chemically classified as a pregna-4,6-diene derivative. This compound is recognized as a potent, modern, high-affinity progestin, often classified as a fourth-generation progestin.

The role of Nomegestrol acetate in combination with estrogen for hormonal contraception is clinically recognized. This medicine has an established function in providing reliable family planning options globally. Its classification as a potent synthetic progestogen means it is designed to interact with specific cellular targets to substitute or modulate the effects of the body's natural hormone, progesterone.


Nomegestrol Acetate: Composition and Pharmaceutical Form

Nomegestrol acetate is most commonly available as an oral tablet that is swallowed, which provides a convenient route of administration. The drug preparation often takes the form of a fixed-dose combination product, typically paired with estradiol, a form of estrogen that is chemically identical to the natural hormone produced by the body. This pairing with a natural estrogen is a key differentiating feature from many older contraceptives that utilize different synthetic estrogens.

The solid oral dosage form consists of the active ingredient embedded within inactive constituents for tableting and coating. This hormonal combination is administered in a consistent dose regimen, ensuring predictable delivery.


The General Purpose of Nomegestrol (Nogest)

The compound is highly selective in nature, characterized by minimal binding to other steroid receptors like the androgen receptor. This indicates that the medicine is targeted in its action. The primary general purpose of Nomegestrol acetate is to provide reliable hormonal regulation by acting as a strong progesterone receptor agonist.

This synthetic hormone mimics the signal of natural progesterone while also exerting a strong antigonadotropic effect, meaning it suppresses the hormonal feedback loop that controls ovulation. This comprehensive mechanism ensures the consistent control over the reproductive cycle, which is the general benefit delivered by this hormonal preparation.

Regulatory References

  1. WHO-EssentialList

What side effects are possible with Nogest?

Possible side effects and safety information

The safety profile of Nomegestrol Acetate (Nogest) is defined by a formal system of adverse drug reaction classification, as established in official regulatory documents. Adverse reactions are grouped by the physiological system affected and their reported frequency.

Frequency-Classified Adverse Reactions

The following effects are classified by their reported frequency in clinical use, based on regulatory standards:

Classification Examples of Documented Effects (System-Organ Class)
Common (ge 1/100 to < 1/10) Headache, depressive mood/depression, weight increase, acne, nausea, changes in menstrual bleeding (amenorrhea, metrorrhagia).
Uncommon (ge 1/1,000 to < 1/100) Migraine, fluid retention, dry skin, chloasma, alopecia, hirsutism, vertigo, breast enlargement.
Rare (ge 1/10,000 to < 1/1,000) Venous Thromboembolism (VTE), Arterial Thromboembolism (ATE), hepatic tumours, hypersensitivity reactions.

Serious Safety Considerations

The official labeling documents rare but serious risks, including the potential for Venous Thromboembolism (VTE) and Arterial Thromboembolism (ATE). Nomegestrol Acetate is also associated with a rare risk of developing hepatic tumours (benign or malignant).

Regulatory safety information outlines specific circumstances under which the medicine must not be used (contraindications). This includes individuals with severe hepatic impairment, a current or history of VTE or ATE, and known or suspected hormone-sensitive malignancies. Changes in menstrual bleeding patterns are often observed, particularly at the start of treatment.

Overdose and Emergency Response

Nomegestrol acetate, the active component in Nogest, has been studied for its potential effects in cases of accidental or intentional overdose. In general, serious adverse effects following an acute overdose of progestogens like Nomegestrol Acetate are considered unlikely.

Potential Overdose Symptoms

Symptoms that have been reported with high doses of this class of medication are typically mild and may include:

  • Nausea and Vomiting
  • Breast Tenderness
  • Vaginal Bleeding: Withdrawal bleeding may occur in women, or slight vaginal bleeding in young girls, occurring 2 to 7 days after the overdose.

Nomegestrol Acetate has been administered alone at dosages significantly higher than the recommended therapeutic dose in clinical trials without reports of serious adverse effects. There is no specific antidote for an overdose of Nogest, and treatment is generally supportive and symptomatic.

When to Seek Help

Immediate medical attention is necessary if you suspect a significant overdose or if the person experiences severe symptoms. Call your local emergency services or a poison control center for professional guidance. While an overdose is unlikely to be life-threatening, prompt consultation ensures appropriate monitoring and care. Be prepared to provide the name of the medication, the amount taken, and the time the overdose occurred.

Therapeutic Uses of Nogest

Nomegestrol Acetate is a hormonal agent commonly used for long-term contraception and for managing various gynecological and menstrual cycle disorders. The medication is applied across therapeutic domains, including its role in birth control, alongside its utility in other hormonal contexts.

Therapeutic Scope and Key Benefits

The medication is generally applied in situations where patients experience episodic or fluctuating manifestations, playing a role in managing family planning goals and may assist with maintaining a more manageable menstrual cycle pattern. Nomegestrol Acetate is relevant for easing symptoms related to physical discomfort, such as heavy menstrual bleeding (menorrhagia) and severe menstrual cramping (dysmenorrhea). It is also used to address challenging symptoms of the severe Premenstrual Syndrome (PMS) or PMDD and androgen-related signs like acne and seborrhea.

Quick Fact: Support for Menstrual Symptoms
Supports easing the intensity of menstrual pain and the volume of blood loss, often used when symptoms interfere with daily functioning.

Eligibility and Restrictions for Use

The official eligibility profile for Nomegestrol Acetate is strictly defined by government regulatory agencies, establishing both approved populations and absolute contraindications. Use is allowed for women of reproductive age requiring hormonal contraception or management of specific menstrual disorders.


Regulatory Eligibility Constraints

Eligibility Status Defined Population Constraints
Contraindicated (Must not use) Individuals with a current or history of Venous or Arterial Thromboembolism (VTE/ATE), known hereditary clotting disorders, severe hepatic disease, benign or malignant liver tumours, and known or suspected hormone-sensitive malignancies. The medicine is also strictly contraindicated during pregnancy and in cases of undiagnosed genital bleeding.
Restricted or Not Established Safety and efficacy have not been established in adolescents under 18 years of age. Use is not recommended for women who are breastfeeding. The medicine must also be discontinued prior to any major surgery involving prolonged immobilisation.

These official restrictions strictly limit the eligible user base to those who do not present with the specified vascular, hepatic, or oncologic high-risk conditions, as outlined in the official prescribing information.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Nomegestrol acetate's interaction profile is primarily defined by its metabolism through the Cytochrome P450 3A4 (CYP3A4) enzyme system. Co-administration with medicinal products that modulate this enzyme can significantly alter the medicine's plasma concentration, a pharmacokinetic interaction.

Interaction Type Examples of Interacting Substances Outcome
CYP3A4 Inducers Rifampicin, certain anticonvulsants (e.g., Phenytoin), St. John's Wort Documented to decrease serum concentration and exposure.
CYP3A4 Inhibitors Potent antifungals (e.g., Ketoconazole) Documented to increase serum concentration and exposure.

The use of nomegestrol acetate is contraindicated in patients with a current or history of meningioma. Furthermore, the medicine is contraindicated in patients with severe hepatic disease because impaired metabolism creates a risk of drug accumulation.

A specific pharmacodynamic caution exists for co-administration with certain Hepatitis C Virus (HCV) combination regimens (e.g., Ombitasvir/Paritaprevir/Ritonavir), due to a documented risk of elevated liver enzyme (ALT) levels. An official administration rule requires compensation if severe gastro-intestinal disturbance occurs within three to four hours of taking the active tablet, as this may lead to incomplete absorption.

Mechanism of Action

How Nomegestrol Acetate Works

Nomegestrol acetate (Nogest) is a synthetic steroid that functions primarily as a progestin, acting as an agonist of the progesterone receptor (PR). Its mechanism is centered on binding to the progesterone receptor, thereby modulating gene expression and physiological processes under hormonal control.


Specific Progesterone Receptor Binding

Nomegestrol acetate exhibits high affinity and selectivity for the intracellular Progesterone Receptor (PR) within target cells, including the endometrium and hypothalamus. This binding initiates a conformational change in the receptor, allowing the complex to migrate to the nucleus. Here, the complex interacts with Progesterone Response Elements (PREs) in the DNA, which initiates or suppresses the transcription of specific genes that regulate cellular differentiation and reproductive cycles.


Modulation of Hypothalamic-Pituitary-Ovarian (HPO) Axis

By acting centrally, this synthetic progestin exerts negative feedback on the hypothalamus and pituitary gland. This action suppresses the pulsatile release of Gonadotropin-Releasing Hormone (GnRH) and, consequently, the pituitary's output of Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH). This suppression limits ovarian follicular development and prevents the LH surge, which is necessary for ovulation.

Dosage and Administration Information

How to Use Nogest (Nomegestrol Acetate)

The usage of Nomegestrol Acetate follows established administration protocols. The medication is primarily administered via the oral route in the form of film-coated tablets.

Dosing and Cyclic Schedule

For hormonal contraception, Nomegestrol Acetate is used in a fixed-dose combination (2.5 mg Nomegestrol Acetate and 1.5 mg Estradiol) following a 28-day cyclic regimen. This involves taking one tablet daily for 28 consecutive days. The regimen is structured as 24 days of active tablets followed by 4 days of placebo tablets.

Usage Pattern Standard Administration Protocol
Route & Frequency Oral, once daily
Contraception Dose 2.5 mg Nomegestrol Acetate / 1.5 mg Estradiol
Monotherapy Dose Typically 3.75 mg to 5 mg daily for gynecological uses

Administration Conditions and Protocol

The daily tablet must be taken at about the same time each day. Intake is without regard to meals. To ensure the regimen's integrity, tablets must be consumed in the precise order directed on the blister packaging.

The protocol for managing a missed active tablet indicates that protection is maintained if the tablet is taken within less than 12 hours of the scheduled time. If vomiting occurs within 3–4 hours of taking an active tablet, the dose is considered missed, and a new tablet should be taken to maintain the sequence. The regimen requires continuous pack-to-pack use with no extended break in daily tablet intake.

High-dose monotherapy use for specific gynecological disorders is restricted to the lowest effective dose for the shortest possible duration.

Recent Clinical Evidence

Research evidence / Overview of studies

Overview of Clinical Research

Current research has evaluated the activity of Nomegestrol Acetate (NOMAC) and was examined for its use in the management of symptoms associated with gynecological disorders and for contraception, primarily in combination with 17beta-estradiol (E2). Multiple randomized, placebo-controlled trials, and large-scale, prospective, active surveillance studies have been conducted across various patient populations, involving thousands of women.

The primary goal of these studies was to investigate changes in chronic symptom scores, assess contraceptive efficacy, and examine the medication's safety profile relative to other hormonal treatments.


Key Findings from Clinical Trials

Contraceptive Efficacy and Cycle Control

  • Efficacy: Comparative studies indicated that the NOMAC/E2 combination demonstrated a difference in outcome compared to placebo and other contraceptive formulations in primary efficacy measures (e.g., Pearl Index). The long half-life of NOMAC (approximately 46–50 hours) is theorized to contribute to maintaining effectiveness, even in cases of a missed dose.
  • Cycle Patterns: Research found that users of the combination product frequently reported shorter, lighter scheduled bleeding, or an absence of scheduled bleeding, compared to some other contraceptive regimens.

Safety and Tolerability Profile

  • Side Effects: The most frequently reported adverse events in clinical trials included acne, weight gain, headache, and irregular withdrawal bleeding. These events were generally described as mild to moderate.
  • Metabolic Impact: Preliminary studies suggest that NOMAC/E2 exhibits less influence on markers of coagulation, fibrinolysis, lipid profiles, and carbohydrate metabolism compared to combined oral contraceptives containing ethinyl estradiol and certain progestins. The most common serious adverse event reported in clinical trials was elevated liver enzymes, which led to discontinuation in a small percentage of participants.

Gynecological Applications

  • Symptom Reduction: Randomized studies assessing the use of vaginal rings containing NOMAC and E2 in women with primary dysmenorrhea (severe menstrual pain) reported a significant reduction from baseline in mean menstrual pain score compared to placebo. NOMAC has also been evaluated as monotherapy and in hormone replacement therapy for gynecological disorders and menopausal symptoms.

Frequently Asked Questions (FAQ)

Common questions about Nogest (Nomegestrol Acetate) (FAQ)

Q: How long does it usually take to see an effect after starting Nogest?

Official product information for the combined oral contraceptive formulation indicates that reliable contraceptive protection is established after the user has completed seven consecutive days of uninterrupted active tablet-taking. Following the prescribed regimen is necessary for the contraceptive effectiveness to be maintained, as described in the official instructions. For other purposes, the time to therapeutic effect may vary.


Q: Why is Nogest sometimes prescribed cyclically instead of continuously?

The official daily regimen is structured as 24 active tablets followed by 4 inactive (placebo) tablets. This cyclic schedule is designed so that a withdrawal bleed, often referred to as a 'period,' will occur during the days the inactive tablets are taken. This structured pattern helps maintain a continuous daily habit while allowing for hormonal withdrawal.


Q: What kind of follow-up is needed while taking Nogest?

Regulatory documents state that patients should be examined periodically, with the frequency and nature of the check-ups adapted to the individual patient's circumstances and generally occurring every 6 to 12 months. This periodic monitoring is detailed in the official safety information.


Q: Can Nogest affect the results of a lab test?

Official medical information states that the use of contraceptive steroids can potentially influence the results of certain laboratory tests. Official guidance suggests informing relevant healthcare providers or laboratory personnel that the medication is being taken before any lab work is conducted.


Q: Can Nogest be taken by people with a history of migraines?

Official safety documents list migraine or severe headache as a condition that requires close medical supervision during treatment. Furthermore, official safety documents list the new onset of a migraine-type headache as a reason for immediate medical consultation regarding withdrawal of the therapy.


Q: Is Nogest considered a synthetic or a natural hormone?

Nomegestrol Acetate itself is classified as a synthetic progestogen, which means it is a man-made hormone designed to act like the body's natural progesterone. When used in combination products, it is paired with estradiol, which is chemically identical (or 'bioidentical') to the estrogen naturally produced by the ovaries.


Q: How does Nogest affect the endometrium (lining of the uterus)?

The mechanism of action involves Nomegestrol Acetate acting on the progesterone receptors, which results in changes to the endometrium. Official information indicates that the medication works in part by thinning the lining of the womb.


Q: Will Nogest stop my period completely?

The absence of withdrawal bleeding, known as amenorrhea, is a very frequent side effect that may occur when taking this medication. Official data indicates that the rate of absent bleeding tends to increase the longer the product is used. The appearance of amenorrhea is a frequent effect that can be discussed with a healthcare provider if there are concerns.


Q: Is Nogest safe for people with lactose intolerance?

Official product labeling states that the active and inactive tablets contain lactose monohydrate. Individuals with a known or suspected intolerance to lactose can refer to this information for their decision-making.


Q: Can I take herbal supplements while I am on Nogest?

Official safety information documents that interactions may occur between this medicine and products that induce hepatic enzymes, which can potentially reduce the effectiveness of the drug. Specific mention is made of preparations containing the herbal remedy St. John’s Wort.


Q: What should I do if the side effects of Nogest feel severe?

The official product information outlines symptoms that require immediate medical attention (e.g., signs of a blood clot or a significant increase in blood pressure). Regulatory documents emphasize the importance of seeking medical review for any serious symptoms or unlisted side effects.


Q: Does Nogest change my libido?

Official regulatory documents list a decreased sex drive (libido) as a common undesirable effect reported by users in clinical trials.


Q: How quickly does Nogest leave the body after I stop taking it?

Pharmacokinetic data indicates that Nomegestrol Acetate has an average terminal elimination half-life of approximately 50 hours. The half-life refers to the time it takes for half of the medication to be cleared from the body.


Q: Is Nomegestrol Acetate the same as medroxyprogesterone acetate (MPA)?

While both are synthetic progestogens, Nomegestrol Acetate is chemically distinct from medroxyprogesterone acetate. Official pharmacological data describes Nomegestrol Acetate as a potent, highly selective agonist of the progesterone receptor.


Q: If I have a surgery planned, should I stop taking Nogest?

Official safety documentation highlights that because the risk of venous thromboembolism (VTE) increases with major surgery or prolonged immobilization, the use of this medication is a critical factor to be considered in pre-operative planning.


Q: Does Nogest affect blood pressure?

Official safety data indicates that an increase in blood pressure is a reported undesirable effect. Regulatory documents list a significant increase in blood pressure as a factor requiring immediate medical review for possible withdrawal of therapy.


Q: Is it necessary to use a backup contraceptive method with Nogest?

Official directions require a barrier method of contraception to be used when starting the treatment until seven consecutive active tablets have been taken. A barrier method is also advised if certain conditions for a missed dose are not met, as outlined in the official prescribing information.


Q: Is Nogest meant to be a short-term or long-term treatment?

When used for oral contraception, the product is taken daily for 28 consecutive days for as long as contraception is required. The product information does not impose a fixed limit on the duration of contraceptive use for this indication.


Q: Does Nogest cause acne or improve it?

Acne is listed in regulatory documents as a very common undesirable effect, meaning it is an effect reported by more than 1 in 10 users during clinical use. This indicates that developing or worsening acne is a frequent expectation of treatment.


Q: Is it safe to take Nogest if I am breastfeeding?

Official regulatory guidance advises that the use of combined hormonal contraceptives is generally not recommended until a breastfeeding mother has completely weaned her child.


Q: What happens if I start taking Nogest later than my doctor instructed?

If the active tablet-taking is started later than recommended (e.g., after the fifth day of the menstrual cycle), the official regimen requires a barrier method of contraception to be used for the first seven days of active tablet-taking to ensure effectiveness.


Q: Do any common OTC medications interact significantly with Nogest?

The official interaction profile is primarily focused on products that affect liver enzymes, such as certain antibiotics, anticonvulsants, and the herbal remedy St. John’s Wort. The official interaction profile is primarily focused on products affecting liver enzymes, such as certain antibiotics, anticonvulsants, and St. John’s Wort.


Q: Does Nogest cause headaches?

Headache is listed in regulatory documents as a common undesirable effect, meaning it is an effect reported in clinical trials by 1 to 10 users in every 100.


Q: Is it possible to be allergic to Nomegestrol Acetate?

Hypersensitivity to the active substance(s) or to any of the inactive ingredients (excipients) is an absolute contraindication to the use of this medication, as outlined in official prescribing information. Hypersensitivity reactions are also listed as a rare undesirable effect.

How should Nogest be stored and disposed of?

Storage and Disposal of Nomegestrol Acetate

Official regulatory documents define specific requirements for the storage and disposal of Nomegestrol Acetate-containing products to maintain stability and comply with environmental mandates.

Required Storage Conditions

Condition Type Requirement (Regulatory Standard)
Temperature Store at a temperature below 30 C
Protection Keep the product out of direct light and away from moisture.
Packaging Must remain in its original packaging (e.g., blister strip).
Child Safety Store in a safe location, out of the sight and reach of children.

Official Disposal Instructions

Disposal must strictly adhere to local, regional, and national regulations for pharmaceutical waste. Nomegestrol Acetate is chemically classified as very toxic to aquatic life with long-lasting effects. Therefore, it is mandatory to avoid all release to the environment, including not disposing of the product via household wastewater systems. Unused or expired medication should be taken to an authorized collection point or pharmacy take-back scheme.

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

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