Microlut

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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 Microlut

Property Description
Active ingredient Levonorgestrel
Form Coated Tablet (Oral contraceptive preparation)
Pharmacological class Progestogen-only pill (POP), Hormonal contraceptive
Common use Birth control, Prevention of pregnancy
Origin Synthetic progestin

Identity, Classification, and Unique Form

Microlut is a prescription-only medication classified as a Progestogen-only pill (POP), frequently referred to as the minipill. This product, historically associated with Bayer AG (Germany) manufacture, is delivered via the oral route for systemic delivery in the form of a coated tablet. Its defining characteristic is its structure as a monophasic formulation containing a single active ingredient, a progestin, which structurally distinguishes it from combined oral contraceptives that contain estrogen. This single-hormone structure is clinically recognized as a key option for women of reproductive age who require or prefer to avoid estrogen due to specific health concerns.

Active Ingredient and Synthetic Origin

Providing the essential contraceptive action is the active ingredient, Levonorgestrel (INN). This substance is an established synthetic progestin belonging to the Gonane progestin family. Its vital role in public health is confirmed by its inclusion on the World Health Organization (WHO) List of Essential Medicines. Levonorgestrel functions as the progestin-dominant compound in the tablet, maintaining its concentration throughout the continuous dosing schedule.

General Purpose and Contraceptive Role

The primary general therapeutic purpose of Microlut is to reliably facilitate birth control and the prevention of pregnancy. This is achieved through the Levonorgestrel's influence on the female reproductive tract. Its action results in two main effects: inducing profound cervical mucus thickening, thereby creating a barrier to sperm, and causing endometrial alteration that changes the uterine lining to prevent the attachment of a fertilized egg. This consistent action fulfills the drug's core purpose as a trusted contraceptive agent.

Regulatory References

  1. Levonorgestrel on WHO Essential Medicines List
  2. WHO Essential Medicines List for Levonorgestrel

What side effects are possible with Microlut?

Possible Side Effects and Safety Information

Official regulatory documentation classifies the possible side effects of Levonorgestrel, the active ingredient in Microlut, into frequency categories based on clinical data. The most frequently observed safety characteristic is irregular bleeding patterns.

Frequency-Classified Adverse Reactions

Adverse effects are formally categorized based on their incidence in clinical use:

  • Very Common (Affects 1 or more in 10 users): Irregular bleeding, which may manifest as spotting, infrequent bleeding, or the complete absence of bleeding (amenorrhea). This pattern is often noted to be more frequent at the start of treatment.
  • Common (Affects 1 to 10 in 100 users): Side effects affecting various systems, including headache, nausea, breast tenderness, mood changes, depressed mood, acne, and weight change or gain.
  • Uncommon (Affects 1 to 10 in 1,000 users): Reactions such as vomiting, dizziness, and rash.

Serious Safety Considerations and Restrictions

Regulatory sources document a set of rare but serious risks, as well as definitive constraints on use:

  1. Vascular and Hepatic Risks: The medicine is restricted for use in individuals with pre-existing or a history of severe hepatic disease or hepatic tumours (benign or malignant). The potential for Venous Thromboembolism (VTE) is documented, as is the need to evaluate for ectopic pregnancy if pregnancy occurs.
  2. Malignancy Constraint: Microlut is contraindicated in cases of known or suspected sex hormone-dependent malignancies, such as breast cancer, and in the presence of undiagnosed vaginal bleeding.

Overdose and Emergency Response

Overdosing on Microlut (a progestogen-only pill containing levonorgestrel) is generally not expected to be life-threatening, even if a large number of tablets are taken. The medication has low acute toxicity. However, an overdose may still lead to uncomfortable or concerning symptoms.

Potential Overdose Symptoms

Symptoms following an accidental or deliberate overdose are typically hormonal side effects seen in a higher concentration. These may include:

  • Gastrointestinal Effects: Nausea and vomiting.
  • Vaginal Bleeding: Withdrawal bleeding, often heavy, may occur two to seven days after the overdose.
  • Other Symptoms: Breast tenderness, headache, discolored urine, or mood changes.

When to Seek Medical Help

Immediate professional assistance is warranted in specific situations, regardless of the cause:

  • Serious Intent: If the overdose was deliberate, seeking immediate help for a mental health evaluation is crucial.
  • Severe Symptoms: Call emergency services immediately if you experience signs of a serious reaction, such as difficulty breathing, severe chest pain, sudden or severe abdominal pain, or loss of consciousness.
  • Guidance: For any suspected overdose, contact a poison control center or a healthcare provider for advice on monitoring symptoms and appropriate next steps. If symptoms like heavy bleeding or persistent vomiting occur, medical evaluation is necessary.

Therapeutic Uses of Microlut

What Microlut Treats: Main Uses and Benefits

Microlut is commonly used within therapeutic areas involving fertility management and patient health needs where estrogen is medically restricted. Its application is relevant in managing symptomatic concerns related to the avoidance of pregnancy, excessive menstrual bleeding, and cyclical uterine discomfort.

The primary purpose of the medication is to provide scheduled birth control and prevention of pregnancy. This is a relevant option for patient groups for whom estrogen is restricted, such as women with certain cardiovascular concerns, a history of vascular events, or specific types of migraine, and may assist with maintaining functional stability in these symptomatic contexts. Furthermore, it is a relevant option for hormonal contraception in the postpartum phase for women who are actively breastfeeding.

“The progestogen-only composition provides a supportive therapeutic benefit, offering assistance when avoiding estrogen is a medical necessity.”

Beyond contraception, it is used in situations involving patterns of heavy menstrual bleeding and associated cyclical uterine discomfort, supporting the patient during difficult episodes by easing distress.


Quick Fact: Support for Menstrual Symptom Management Microlut may be part of symptomatic management during periods of excessive blood loss and painful cramping, assisting with maintaining functional stability.

Eligibility and Restrictions for Use

Microlut (levonorgestrel 30mu g) is a progestogen-only contraceptive pill (POP) and is contraindicated for use in specific populations as defined by regulatory documents.

Populations Who Must Not Use Microlut (Contraindications)

Contraindicated Condition/Status Eligibility Classification
Known or suspected pregnancy Absolute exclusion
Active or past thromboembolic disorders (e.g., DVT, PE, stroke, myocardial infarction) Absolute exclusion
Severe hepatic disease (until liver function is normal) or hepatic tumors Absolute exclusion
Known or suspected sex hormone-dependent malignancies (e.g., breast cancer) Absolute exclusion
Undiagnosed vaginal bleeding Absolute exclusion
Known hypersensitivity to levonorgestrel or any excipients Absolute exclusion

Special Eligibility Rules

Microlut is not intended for use in women who are pre-menarcheal (before their first period) or who are postmenopausal.

Pregnancy and Lactation: Use is prohibited during pregnancy. The product is frequently used in breastfeeding women, as it minimally affects milk supply, though small amounts of the drug are known to pass into breast milk.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Some medicines may interfere with the effectiveness of Microlut, potentially reducing protection against pregnancy. Conversely, Microlut may also affect the action of other medicines. Patients must inform their healthcare provider of all prescription and non-prescription medicines, supplements, or herbal products they are taking.

Products that may affect Microlut

The following categories and specific medicines are known to have clinically significant interactions, primarily due to enzyme-inducing properties which may reduce the concentration of the active substance (levonorgestrel):

Product Category Examples of Interacting Medicines
Tuberculosis treatments Rifampicin, Rifabutin
Epilepsy (Anticonvulsants) Phenytoin, Primidone, Barbiturates, Carbamazepine, Topiramate, Lamotrigine
HIV/HCV treatments Ritonavir, Nevirapine, Boceprevir, Telaprevir
Antifungals Griseofulvin, Ketoconazole
Antibiotics Penicillins, Tetracycline, Macrolides (e.g., Erythromycin)
Herbal Medicine St John's Wort

Other Notable Interactions

  • Cyclosporin: Microlut may affect the way the immunosuppressant cyclosporin works.
  • Diabetes Medication: For women with diabetes, the required dose of anti-diabetic medication may need to be adjusted, as Microlut can have a slight effect on peripheral insulin resistance and glucose tolerance.
  • Blood Tests: Microlut may interfere with the results of certain blood tests. The laboratory staff should be informed if you are taking this medicine.

Required Precautions

If any of the interacting medicines are taken concurrently, additional non-hormonal barrier methods of contraception (such as condoms) must be used. This additional protection is required not only while taking the interfering medicine but also for a period of time after stopping it, as advised by a healthcare professional.

Mechanism of Action

The action of Microlut is governed by its single active ingredient, Levonorgestrel, which functions as an agonist at the Progesterone Receptor (PR). This molecular interaction modifies genetic activity within target reproductive cells, initiating a series of physiological changes focused on creating barriers to conception.

Targeting the Progesterone Receptor

This interaction modulates key physiological processes by influencing steroid hormone signaling patterns.

Peripheral Contraceptive Barriers

By acting on the cervix and endometrium, the mechanism initiates signaling sequences that lead to the thickening of cervical mucus and the structural modification of the uterine lining. These actions create physical local barriers to sperm penetration and implantation.

Modulating the Hormonal Control Axis

Levonorgestrel exerts a systemic negative feedback influence on the Hypothalamic-Pituitary-Ovarian (HPO) axis. This action partially suppresses the release of key hormones, including LH and FSH, engaging mechanisms that regulate the timing of ovarian activity, which may result in **variable suppression of ovulation.***>>

Dosage and Administration Information

Official Administration Guidelines: Levonorgestrel 30 mug Tablet

Microlut is an oral contraceptive delivered as a coated tablet containing a single active ingredient, 30 mu g Levonorgestrel. The administration protocol is characterized by a precise, continuous daily schedule without any tablet-free interval.

Dosing and Scheduling

The standard regimen is one tablet daily, which represents the maximum recommended dose per 24-hour interval. To maintain consistent efficacy, the tablet must be taken at the same time each day. General instructions emphasize that the interval between two consecutive tablets must not exceed 27 hours (i.e., being more than three hours late). Tablets are swallowed whole with a little liquid, and intake is not dependent on meals (may be taken with or without food).

When one pack of 28 tablets is finished, the next pack is started immediately on the following day, supporting the drug’s long-term continuous use.

Procedural Constraints

Clinical guidelines outline critical rules for managing the start of treatment or missed doses:

Administration Scope Official Instruction
Starting Use If initiated later than Day 1 of the menstrual cycle, an additional non-hormonal barrier method must be used for the first seven days of tablet intake.
Missed Dose If the tablet is taken more than three hours late ( >27 hours elapsed), the missed dose should be taken immediately. An additional barrier method of contraception must be used for the subsequent seven days.

These instructions define the standardized approach to using the medicine, strictly adhering to the continuous daily oral regimen and its associated critical timing requirements.

Recent Clinical Evidence

Microlut is an oral progestogen-only contraceptive (POP), commonly known as the mini-pill. Its active ingredient is levonorgestrel (30 micrograms per tablet). As a POP, it differs from combined oral contraceptives by containing only one hormone and no estrogen.

Efficacy and Mechanism of Action

Clinical research has demonstrated that when used correctly, progestogen-only pills like Microlut are highly effective at preventing pregnancy. Typical-use effectiveness rates are reported to be approximately 93%.

The mechanism of action is primarily achieved through several biological effects, without consistently inhibiting ovulation, unlike combined pills:

Primary Contraceptive Effect Description
Cervical Mucus Thickening Makes the mucus at the entrance of the uterus (cervix) thicker, creating a barrier that restricts sperm movement.
Endometrial Changes Alters the lining of the uterus (endometrium), making it less receptive to the implantation of a fertilized egg.

Safety and Trial Population

Microlut is often a suitable option for individuals who cannot use contraceptives containing estrogen, such as those with a history of certain circulatory conditions or those who are breastfeeding.

Studies have shown that the risk of venous thromboembolism (blood clots) associated with progestogen-only pills is lower than the risk associated with combined hormonal contraceptives and is also lower than the risk of blood clots during pregnancy. Trials and clinical use have informed its application across various adult groups and pediatric populations (post-menarche).

Frequently Asked Questions (FAQ)

Common questions about Microlut (FAQ)

Q: How quickly does Microlut start working?

Regulatory guidance indicates that if Microlut is started later than the first day of the menstrual cycle, an additional non-hormonal barrier method is required for the first seven days of tablet intake. This necessity reflects the period required for the full contraceptive effects to become established.

Q: What should I do if I miss a Microlut pill?

Official guidance states that if a tablet is taken less than three hours late, the missed pill should be taken immediately and the user should continue with the next pill at the usual time. If the tablet is taken more than three hours late (over 27 hours elapsed), official documents recommend the use of an additional non-hormonal barrier method for the subsequent seven days.

Q: Is it normal to have irregular bleeding when starting Microlut?

Yes, irregular bleeding patterns are classified as a very common side effect of Microlut, potentially affecting 1 or more in 10 users. This may include spotting, infrequent bleeding, or the absence of bleeding (amenorrhea). This pattern is often noted in official documents to be more frequent during the start of treatment.

Q: Are headaches a common side effect of Microlut?

According to official product information, headaches are listed as a common side effect of Microlut, which affects between 1 and 10 in 100 users. Regulatory information notes that individuals experiencing concerning side effects should consult their healthcare provider.

Q: Can Microlut affect my mood or emotional health?

Official regulatory documents classify both mood changes and depressed mood as common side effects of the medicine. These common effects affect up to 10 in 100 users. Regulatory information notes that individuals experiencing concerning side effects should consult their healthcare provider.

Q: Does Microlut cause weight gain for most people?

Weight change or gain is listed in official documents as a common side effect of Microlut. A common side effect affects between 1 and 10 in 100 users.

Q: Can Microlut be taken indefinitely for a long period?

Official administration guidelines describe a continuous daily schedule for Microlut, supporting long-term, continuous use. The long-term appropriateness of the medication is typically assessed during routine healthcare visits.

Q: Does the time of day I take Microlut matter?

Yes, strict timing is emphasized in the official instructions. The tablet must be taken at the same time each day. Official instructions specify that the interval between two consecutive tablets must not exceed 27 hours for efficacy, emphasizing the need for strict timing.

Q: Can Microlut affect the results of blood tests?

Yes, official product information states that Microlut may interfere with the results of certain blood tests. The medicine's label states that laboratory staff should be informed if the patient is taking this medicine.

Q: What is the difference between Microlut and combined pills?

Microlut is classified as a progestogen-only pill (POP), often called the mini-pill, and contains only one active hormone, levonorgestrel. In contrast, combined oral contraceptives contain two types of hormones: a progestin and an estrogen. This single-hormone structure is often cited as an option for individuals who need to avoid estrogen.

Q: Are there any herbal supplements that interact with Microlut?

Yes, official regulatory documents specifically name St John's Wort as a herbal medicine known to have clinically significant interactions with Microlut. These types of interactions may reduce the concentration of the active substance, which can compromise the medicine’s action.

Q: Can women who are breastfeeding use Microlut?

Official documents note that Microlut is frequently used in breastfeeding women. It is described as having only a minimal effect on milk supply, although small amounts of the active drug are known to pass into breast milk.

Q: Is Microlut suitable for women over 35?

The official product constraints specify that Microlut is not intended for postmenopausal women. Consultation with a healthcare provider is necessary to determine individual eligibility and assess overall health factors.

Q: Can taking antibiotics reduce the effectiveness of Microlut?

Regulatory information indicates that several categories of antibiotics are known to interfere with the effectiveness of Microlut. Listed examples include certain Penicillins, Tetracycline, and Macrolides. In such cases, additional non-hormonal barrier methods of contraception may be necessary, as determined by a healthcare provider.

Q: Is vomiting or severe diarrhea a concern regarding pill absorption?

Official warnings indicate that severe gastrointestinal disturbance, such as vomiting or severe diarrhea, may compromise the absorption of the active ingredient. The medicine's label indicates that such an event may compromise absorption, and a healthcare provider should be consulted for specific guidance on contraceptive measures.

Q: What happens if Microlut is stopped suddenly?

Regulatory information indicates that when the mini-pill is stopped, fertility is expected to return to normal within a very short time. The statement implies the end of the drug’s contraceptive effects.

Q: Can Microlut cause acne or breakouts?

Acne is listed in official regulatory documents as a common side effect of the medicine. A common side effect affects between 1 and 10 in 100 users.

Q: How long does it take for fertility to return after stopping Microlut?

Official patient leaflets indicate that fertility is expected to return to normal within a very short time of stopping the mini-pill.

Q: Does Microlut help regulate my cycle?

Microlut is intended solely for contraception. The most frequently observed side effect of the pill is an irregular bleeding pattern, which is the opposite of cycle regulation. This irregularity may include spotting, infrequent bleeding, or the complete absence of bleeding.

Q: Are mood swings a temporary side effect when starting?

Mood changes and depressed mood are classified as common side effects. While regulatory documents note that irregular bleeding is often more frequent at the start of treatment, official product information does not specify a general timeframe for when these other common side effects might subside.

Q: What research evidence exists regarding Microlut?

Clinical research evidence for Microlut, a progestogen-only pill, demonstrates high effectiveness when used correctly. Studies indicate reported typical-use effectiveness rates of approximately 93% at preventing pregnancy.

How should Microlut be stored and disposed of?

How to Store and Dispose of Microlut?

Storage Requirements

Microlut tablets must be stored in the original blister pack in a cool, dry place where the ambient temperature stays below 30 C.

Regulatory documents explicitly instruct that the product must be kept out of the reach of children. A high, locked cupboard is cited as a suitable child-safe location. Storage environments that expose the medicine to destructive heat and dampness are prohibited; these include bathrooms, window-sills, or vehicles.

Handling and Disposal

The integrity of the packaging is vital; the tablets must not be taken if the pack is torn or shows signs of tampering. Furthermore, the product must not be used past the expiry date printed on the packaging.

Any unused, expired, or damaged Microlut must be returned to a pharmacist for disposal. This procedure ensures adherence to official pharmaceutical waste handling guidelines.

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

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