Primolut

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Medically reviewed

Marina Burgos

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 Primolut

Property Description
Active Ingredient Norethisterone (INN)
Form Oral tablet
Pharmacological Class Progestogen (Synthetic Sex Hormone)
General Purpose Regulating the menstrual cycle and controlling the uterine lining
Origin Synthetic estrane steroid derivative

What Type of Medicine is Primolut and What is it Made Of?

Primolut is a prescription-only pharmaceutical preparation whose active ingredient is Norethisterone, a synthetic progestogen (INN) administered as an oral tablet. This medication belongs to the Progestogen pharmacological class, which encompasses synthetic versions of progesterone, and is classified under the ATC code G03DC02. Norethisterone is structurally a 19-nortestosterone derivative and is considered a second-generation progestin. Primolut is typically supplied as an oral tablet of 5 mg of Norethisterone, often manufactured by Bayer, and functions as a single-ingredient product, consisting of the hormone and inert solid excipients, such as lactose monohydrate and maize starch.

Primolut: A Synthetic Version of Progesterone

Norethisterone, the core substance in Primolut, is a manufactured compound with enhanced potency and stability compared to natural progesterone when taken orally. This synthetic origin ensures a strong, reliable systemic effect necessary for therapeutic intervention. Furthermore, the Norethisterone molecule is chemically unique among some progestins because a small fraction of the compound is partially converted, or metabolized, to the potent estrogen, ethinylestradiol, a characteristic that influences its systemic hormonal effects.

What is the General Function of this Progestogen?

The general function of Primolut is to provide a powerful, controlled progestogenic effect, primarily by acting as an agonist for the progesterone receptor. This mechanism allows it to exert direct control over the uterine lining (endometrium), promoting the stabilization of its structure. The medication's consistent hormonal input is a method for managing the timing and stability of the menstrual cycle, influencing the nature of uterine bleeding.

Regulatory References

  1. NIH DailyMed Profile
  2. NIH DailyMed Monograph

What side effects are possible with Primolut?

Possible Side Effects and Safety Information

The safety profile for Primolut (norethisterone) is established by regulatory documents and includes a range of common side effects and rare, serious safety risks, along with specific limitations on who can use the medicine.

Adverse Reactions by Frequency

Official documents classify side effects to indicate how often they may occur:

Frequency Category Selected Adverse Reaction Examples
Common (≥ 1/100 to < 1/10) Headache, nausea, fluid retention (oedema), weight increase, and abnormal uterine/vaginal bleeding (e.g., spotting, amenorrhea).
Uncommon (≥ 1/1,000 to < 1/100) Migraine.
Rare (≥ 1/10,000 to < 1/1,000) Hypersensitivity reactions (allergy), urticaria (hives).
Not Known (Cannot be estimated) Thromboembolic events, dizziness, depression, hepatic function disorders.

Serious Adverse Reactions and Safety Concerns

The most serious safety risks documented in regulatory sources include the potential for:

  • Thromboembolic Events: Both venous (e.g., Deep Vein Thrombosis, Pulmonary Embolism) and arterial (e.g., Myocardial Infarction, Stroke) blood clots. This is a rare, but critical, safety concern.
  • Liver Tumours: Rare reports of benign and malignant hepatic tumours, which can lead to life-threatening intra-abdominal bleeding.
  • Severe Allergic Reactions: Documented instances of hypersensitivity.

Safety Restrictions and Contraindications

The medicine is strictly contraindicated (must not be used) in certain conditions, including:

  • Known or suspected pregnancy or lactation.
  • Active or history of thromboembolic disorders (blood clots) or conditions that significantly increase this risk (e.g., specific types of migraines or diabetes with vascular involvement).
  • Severe hepatic disease (liver disease) or a history of liver tumours.
  • Known or suspected sex hormone-dependent malignancies (e.g., breast or genital organ cancer).

Treatment must be discontinued immediately if symptoms of thromboembolism, new severe migraines, sudden vision/hearing problems, or signs of liver damage occur. It should also be stopped prior to major surgery or prolonged immobilisation to mitigate the risk of blood clots.

Overdose and Emergency Response

Overdose and When to Seek Help

The information in this section is based solely on official prescribing information provided by governmental regulatory authorities and describes only officially documented overdose presentations and required actions.

Regulators state that the toxicity of Norethisterone is generally considered very low, and serious clinical outcomes following an acute overdose are not typically expected.

Documented Overdose Manifestations
Nausea
Vomiting
Breast enlargement (Mastodynia)
Vaginal bleeding (may be delayed)

Required Emergency Actions

Immediate medical attention is required upon any suspected overdosage. Official labeling mandates seeking help even when symptoms are mild, as subsequent clinical management by a healthcare professional is necessary to assess the situation. Individuals must seek emergency medical attention or contact a Poison Control Center immediately.

Treatment is defined as symptomatic and supportive, as no specific antidote for Norethisterone overdose is available. Procedures such as Gastric lavage may be considered by a healthcare provider, particularly if a large overdose is identified and the patient is seen within four hours of ingestion.

Therapeutic Uses of Primolut

What Primolut Treats: Main Uses and Benefits

Primolut (Norethisterone) is commonly used across therapeutic domains where hormonal management is appropriate for certain distressing symptoms. Its use generally centers on stabilizing the menstrual cycle and **easing cyclical discomfort.


Supportive Management of Abnormal Bleeding

The core therapeutic domains include managing menorrhagia (abnormally heavy flow), dysfunctional uterine bleeding (DUB), and secondary amenorrhea. The medication is applied in clinical settings that involve acute or unstable symptom patterns. A key benefit is that it helps manage acute, excessive blood loss and supports the patient during difficult episodes by easing distress caused by severe or unpredictable bleeding.

The medication supports general well-being during symptomatic phases when symptoms create noticeable physiological strain.

Relief from Cyclical Pain and Situational Control

Primolut also helps address symptom clusters that may become intense or disruptive, including severe dysmenorrhea (painful cramping) and the chronic pain associated with endometriosis. It is relevant when short-term symptomatic assistance is needed, such as for the temporary postponement of menstruation. This provides supportive relief when symptoms interfere with routine activities.


Quick Fact: Symptom Management Focus
Is commonly used to help with the easing of pain associated with dysmenorrhea and endometriosis and managing physical PMS symptoms like breast tenderness.

Eligibility and Restrictions for Use

The official regulatory profile for Primolut (Norethisterone) defines strict population eligibility rules, primarily based on contraindications and the requirement for careful medical supervision in certain groups.

Who Must Not Use Primolut (Contraindications)

Primolut is strictly prohibited for individuals with specific, high-risk conditions:

  • A history of or active venous or arterial thromboembolism (e.g., DVT, pulmonary embolism, stroke, or myocardial infarction).
  • Severe active liver disease (until function is normalized) or the presence of liver tumors.
  • Known or suspected sex hormone-dependent malignancies (such as breast or genital cancer).
  • Undiagnosed irregular genital bleeding or migraine with focal neurological symptoms.
  • Pregnancy or lactation/breastfeeding.

Conditional Use and Population Restrictions

Use requires strict medical supervision and careful observation in patients with:

  • Conditions aggravated by fluid retention, such as renal dysfunction or cardiac dysfunction.
  • Non-vascular diabetes mellitus or controlled hypertension.
  • A history of psychiatric depression or epilepsy.

The medicine is not recommended for children and its use is generally not established for the geriatric population.

What should I know about interactions with other medicines?

Interactions with other medicines and products

This section outlines officially documented interaction patterns for Primolut (Norethisterone) as described in government regulatory documents.

Contraindicated Combinations

Co-administration with medicinal products containing ombitasvir/paritaprevir/ritonavir and dasabuvir is formally contraindicated due to interaction risk.

Pharmacokinetic and Metabolic Interactions

Norethisterone's exposure may be significantly reduced by enzyme-inducing agents, which accelerate the drug's clearance by increasing the activity of Cytochrome P450 (CYP) enzymes. This pharmacokinetic interaction can lead to reduced therapeutic effectiveness. Key substances documented as inducers include certain anticonvulsants (e.g., Carbamazepine, Phenytoin), anti-infectives (e.g., Rifampicin), and the herbal product St John's Wort. Furthermore, Aminoglutethimide is reported to decrease progestogen plasma levels.

Pharmacodynamic and Specific Drug Interactions

Special observation is required when Norethisterone is co-administered with drugs that cause fluid retention (e.g., NSAIDs, Vasodilators), particularly in patients with pre-existing conditions like cardiac or renal dysfunction, due to the risk of additive fluid retention. Co-administration with Anticoagulants requires careful consideration due to the potential for an increased thromboembolic risk. Specific drug interactions include the reported alteration of Cyclosporin plasma levels when used concurrently with Norethisterone.

Mechanism of Action

How Primolut Works: Mechanism of Action

Primolut (norethisterone) is a synthetic progestogen that engages mechanisms associated with steroid hormone receptor binding and feedback regulation in the reproductive axis. It exerts its effects across distinct mechanistic domains, influencing both peripheral tissue differentiation and central hormonal signaling pathways.


Receptor Agonism and Endometrial Transformation

This domain covers the drug's core molecular action: it acts as an agonist by binding to progesterone receptors (PRs), specifically in the endometrium. This initiates a signaling sequence that induces the uterine lining to undergo secretory transformation. This action initiates the cellular sequence characteristic of the luteal phase, which provides hormonal support to the differentiated endometrium.


HPO Axis Negative Feedback Modulation

This domain involves the drug's influence on the central hormonal system. It engages mechanisms that influence negative feedback regulation within the Hypothalamic-Pituitary-Ovarian (HPO) axis by suppressing the release of pituitary hormones like LH and FSH. The modification of early molecular steps in the HPO axis inhibits the necessary preovulatory surge of Luteinizing Hormone (LH), leading to the physiological consequence of suppressed ovulation.


Alteration of Local Barrier Mechanisms

This domain addresses the drug's effect on peripheral physiological conditions. It initiates signaling sequences that lead to downstream effects, causing a structural change in the cellular secretions that form the cervical mucus and altering fallopian tube motility. This alters the physical properties of the cervical mucus, resulting in increased viscosity and reduced permeability.

Dosage and Administration Information

Primolut (Norethisterone 5 mg) is administered strictly via the oral route as a tablet that should be swallowed whole with liquid. Usage is based on specific dosing and duration patterns. The medicine may be taken with or without food as the timing relative to meals is not a required condition of administration.

The daily dose ranges widely, from 5 mg to 15 mg, and is typically taken in divided daily doses (once to three times daily). For acute management of dysfunctional uterine bleeding, the regimen involves 5 mg three times daily for 10 consecutive days. In contrast, usage for conditions like secondary amenorrhea usually involves 5 mg once or twice daily for 10 days per cycle, often repeated for 2 or 3 cycles following initial estrogen exposure. For extended use, such as in the management of endometriosis, a continuous daily dose of 5 mg twice daily is followed for a minimum of 4 to 6 months.

Regarding missed timing: if a tablet is forgotten, only the last missed tablet should be taken upon remembering. It is important not to take a double dose to compensate for the skipped one. Administration is primarily designed for adults, and the product is not intended for use in the pediatric population for these uses.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Primolut

Evidence for Use in Managing Abnormal Bleeding and Cycle Control

Research has examined this compound in conditions involving periods of heightened symptoms of heavy menstrual flow, known as menorrhagia, and for the temporary alteration of menstrual timing. This research was evaluated in Randomized Controlled Trials (RCTs) and various retrospective real-world analyses. These studies included women of reproductive age experiencing abnormal bleeding without known structural causes. Studies evaluated measurements related to the timing of bleeding cessation and the volume of blood loss. Findings describe patterns observed in the short term, related to the stability of the uterine lining measured during the study period. For instance, data show patterns related to the swiftness of the response during acute episodes. However, evidence for continuous, long-term use related to reducing recurrence may be largely observational, and follow-up durations were often limited to three cycles.

The use of this compound for postponement of the menstrual cycle was evaluated in research exploring temporary physiological imbalance to delay menses. This research focused on short-term symptom changes in generally healthy women, with studies describing the predictable pharmacological pattern relative to when administration was stopped. The research structure is primarily designed to confirm a time-dependent hormonal effect.

Evidence for Use in Managing Endometriosis and Cyclical Pain

Research has explored the use of this compound in conditions characterized by fluctuating or episodic manifestations that may involve functional limitations, such as endometriosis. Studies were applied in research contexts involving fluctuating or unstable symptoms and examined outcomes related to physical discomfort (like pelvic pain) and patient-reported outcomes describing perceived discomfort. The populations included women with confirmed endometriosis who sought intervention. Because this is a condition where symptoms may vary in intensity, the research often necessitated long-term observation periods, typically six months or more. Findings contribute to understanding symptom patterns related to cyclical pain and discomfort over these extended periods, but data are often derived from older trials. Furthermore, much of the evidence concerning severe dysmenorrhea was observed in trials where endometriosis or abnormal bleeding was studied for the primary focus; dedicated, large-scale studies solely on primary menstrual pain data are still emerging or are less integrated into the core regulatory evidence.

Key Studies & References

  1. A double blinded randomized controlled trial to compare Ormeloxifene and Norethisterone in the treatment of Dysfunctional Uterine Bleeding

Frequently Asked Questions (FAQ)

Common questions about Primolut (FAQ)

Q: What are the most commonly reported side effects of Primolut?

Official documents classify several effects as common, meaning they may affect between 1 in 100 and 1 in 10 users. Commonly cited effects in this frequency category include headache, nausea, fluid retention (oedema), weight increase, and abnormal uterine or vaginal bleeding, such as spotting.

Q: How long after stopping Primolut should a period start?

Regulatory guidance for the use of this medicine in period postponement indicates that the expected withdrawal bleed, which is similar to a period, is generally cited to occur within two to four days after stopping the medication.

Q: What should a patient do if they experience a severe side effect?

Official safety restrictions describe circumstances where treatment discontinuation is required if symptoms of serious adverse reactions, such as those related to blood clots (thromboembolism), occur. Regulatory information advises checking with a healthcare provider immediately if any severe change or concerning symptom is experienced while taking the medicine.

Q: Can Primolut interact with common pain relievers like ibuprofen?

Regulatory documents advise that careful consideration is required when the medicine is taken alongside drugs that cause fluid retention. This includes non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, particularly in patients who have pre-existing heart or kidney conditions.

Q: Is Primolut the same as other period delay pills?

Primolut contains the synthetic hormone norethisterone. Many other medications used for the temporary postponement of menses contain this same active ingredient, though they may be sold under different brand names in different locations.

Q: How quickly does Primolut start to work for delaying a period?

For the purpose of menstrual postponement, official usage instructions state that the medication must begin administration three to five days before the expected start date of the period in order to achieve the defined effect.

Q: Can Primolut affect mood or cause emotional changes?

According to official documentation, some adverse reactions that have been reported include changes in mood, nervousness, and depression. Patients with a history of clinical depression are advised to be carefully observed during therapy.

Q: Are headaches a common side effect of Primolut?

Yes, headache is listed in regulatory documents as a common side effect. This means that a headache may affect between 1 in 100 and 1 in 10 people who use the medication.

Q: Can you still get pregnant while taking Primolut?

The 5 mg formulation of Primolut is prescribed for the treatment of gynecological disorders, not as a primary form of contraception. Official regulatory information indicates the medication is not considered a primary substitute for recognized contraceptive methods.

Q: Is Primolut used for purposes other than period delay or heavy bleeding?

Yes. In addition to regulating heavy menstrual flow and timing, the medication is also officially indicated for conditions such as secondary amenorrhea (the absence of a period) and for the long-term management of endometriosis.

Q: Are there any common foods or drinks that interact with Primolut?

Regulatory guidance mentions that grapefruit and grapefruit juice may increase the amount of norethisterone in the body. Limiting the consumption of grapefruit products is a topic that may be discussed with a healthcare provider.

Q: Can Primolut cause changes in appetite or weight?

Yes. Official documents list weight increase as a common side effect of the medicine. Other adverse reaction reports include anorexia, which is a loss of appetite, and general changes in weight.

Q: Are there research studies on the long-term effects of Primolut?

Research has utilized long-term observation periods, typically six months or more, when studying conditions like endometriosis. However, the available evidence for continuous, long-term use related to reducing recurrence is noted to be largely observational.

Q: Is it normal to have spotting while taking Primolut?

Yes, spotting is explicitly noted in regulatory documents as a type of abnormal uterine or vaginal bleeding that is classified as a common side effect. This indicates it is a commonly documented occurrence during therapy.

Q: Does Primolut have different brand names in other countries?

Yes, the active ingredient in Primolut, which is norethisterone, is sold under different trade names globally. Examples of other brand names include Primolut-Nor and Aygestin.

Q: Is Primolut a type of birth control pill?

The 5 mg formulation of Primolut is specifically indicated for gynecological conditions and is not labeled as a contraceptive. While its active ingredient is used in some lower-dose contraceptives, this specific tablet strength is not intended for birth control.

Q: Why does Primolut help with endometriosis symptoms?

The medication provides a powerful hormonal effect by acting on progesterone receptors in the uterine lining. This action controls the structure of the lining and also works to suppress ovulation by modulating the HPO axis, which is the basis for its use in managing endometriosis symptoms.

Q: Can I take Primolut if I am breastfeeding?

Official regulatory documents state that the medicine is described as strictly contraindicated for use by individuals who are currently pregnant or actively breastfeeding/lactating.

Q: What is the general duration of use for Primolut in official guidelines?

The duration of use is highly variable and depends on the condition being treated, as defined in official guidelines. Regimens can range from a short course of 10 days for acute issues to continuous use for four to six months or more for conditions like endometriosis.

Q: Is Primolut usually taken daily or only as needed?

The medication is generally administered in a daily dose, according to the specific treatment regimen. For most indications, it is taken as divided daily doses (once to three times daily) rather than only as needed.

Q: Is there a risk of withdrawal bleeding after stopping the medicine?

Yes, the expected hormonal effect of the medicine is the occurrence of a withdrawal bleed, which is similar to a period. This is generally cited as expected to occur within a few days after stopping the medication, usually two to seven days.

Q: Can I take Primolut if I have diabetes?

Individuals with non-vascular diabetes mellitus are included in patient groups that require strict medical supervision and careful observation by a healthcare professional during therapy.

Q: Is Primolut known to cause hair loss or growth?

Regulatory documents list both changes in hair growth as possible side effects. Specifically, both loss or thinning of the hair and increased hair growth (known as hirsutism), particularly on the face, have been documented.

Q: Does Primolut affect cholesterol levels?

Regulatory documents note that progestin therapy may have adverse effects on lipid metabolism. For this reason, patients with hyperlipidemias (high cholesterol) are advised to be monitored closely during therapy.

Q: Can Primolut be used to make periods lighter?

Yes, based on official labeling, one of the primary uses of the medication is the management of heavy menstrual flow, which is known as menorrhagia, and other abnormal uterine bleeding.

Q: Does the efficacy of Primolut change over time?

Research has focused primarily on the short-term patterns related to cycle control and acute bleeding cessation. Official information notes that for continuous, long-term use, such as for reducing recurrence, the available evidence is often observational.

Q: What is the evidence base for using Primolut for premenstrual syndrome (PMS)?

While research has explored the medicine’s use for symptoms related to cyclical pain and discomfort, dedicated, large-scale studies focusing solely on the evidence base for premenstrual syndrome (PMS) are generally less integrated into the core regulatory documentation.

Q: How is the action of Primolut described in official medical texts?

Official documents describe the medicine’s action across three mechanistic domains: it acts as an agonist for progesterone receptors in the uterine lining, modulates the HPO axis to suppress ovulation, and alters local barrier mechanisms like cervical mucus.

How should Primolut be stored and disposed of?

Storage and Disposal Requirements

Official regulatory labeling dictates specific conditions for the storage and disposal of Primolut (norethisterone) tablets to ensure stability and safety.


Storage Requirements

  • Temperature and Protection: The medicine must be stored at a temperature that is typically specified to be below 30 C or 25 C and must be kept in a dry place, protected from excess heat and moisture.
  • Packaging: Tablets must remain in their original pack and the container should be kept tightly closed to maintain product quality.
  • Child-Safety: The medication must be stored securely out of the sight and reach of children.

Disposal Instructions

  • Unused Product: Expired or unused Primolut must be returned to a pharmacist or a designated pharmaceutical waste collector for proper disposal.
  • Environmental Protection: Regulatory guidance advises against flushing the tablets down the toilet; if a take-back program is unavailable, U.S. guidance recommends mixing the product with an undesirable substance before discarding it in the household trash.

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

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