Kelnor

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Kelnor

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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 Kelnor

Quick Facts

Property Description
Active Ingredient(s) Ethinyl Estradiol, Etynodiol Diacetate
Form Oral Tablet (Monophasic)
Pharmacological Class Estrogen and Progestin Combination
Common Use Prevention of Pregnancy (Contraception)
Origin Synthetic Hormonal Compound

What Type of Medicine Is Kelnor? (Definition and Classification)

Kelnor is a prescription-only combination hormonal contraceptive formulated for oral use as a tablet. It belongs to the high-level pharmacological category of Estrogen and Progestin Combinations, a class of medicine clinically recognized for its role in family planning. The drug is classified as a monophasic oral contraceptive pill, which means each active tablet contains a consistent, constant dose of the synthetic hormones throughout the cycle. This classification confirms that the medicine is fundamentally designed to modulate reproductive hormones for birth control.

What Hormones Does Kelnor Contain? (Composition and Origin)

The medicine contains two synthetic active ingredients: Ethinyl Estradiol and Etynodiol Diacetate. Ethinyl Estradiol acts as the estrogen component, and Etynodiol Diacetate is a progestin, specifically a prodrug that the body converts into the active progestin Norethisterone. This dual-hormone combination is the defining feature of Kelnor and its generic counterparts, such as Zovia and Demulen. The active ingredients are combined with various solid excipients, such as anhydrous lactose and microcrystalline cellulose, to create the final oral dosage form.

What Is the General Purpose of Kelnor? (High-Level Benefit)

The singular general purpose of Kelnor is the reliable prevention of pregnancy in females of reproductive age. The combined hormonal input achieves this primarily by inhibiting ovulation—the monthly release of an egg—a contraceptive effect supported by pharmacological studies. Additionally, the hormones cause the cervical mucus to thicken and the uterine lining (endometrium) to thin. These actions establish multiple, highly effective barriers, ensuring the medication's foundational role in fertility control.

Regulatory References

  1. DailyMed Label for Kelnor
  2. MedlinePlus Drug Information on Ethinyl Estradiol and Ethynodiol Diacetate

What side effects are possible with Kelnor?

Possible Side Effects and Safety Information

The safety profile of Kelnor, a combination hormonal contraceptive, is formally documented in government regulatory sources, detailing both common reactions and rare but serious risks, classified by organ system and frequency.

Category Regulatory Documentation
Common Adverse Reactions Nausea, Vomiting, Breast tenderness or enlargement, Weight change (increase or decrease), Headaches, Spotting, Breakthrough bleeding, and Fluid retention. Nausea and irregular bleeding may be more prominent during the first few cycles of treatment.
System-Organ Classes Effects are documented across Vascular, Gastrointestinal, Nervous System, Reproductive System and Breast, and Hepatobiliary Disorders (e.g., gallbladder disease, liver tumors).
Serious Adverse Reactions Officially highlighted risks include Thromboembolic Events (Deep Vein Thrombosis, Pulmonary Embolism), Arterial Thromboembolism (Myocardial Infarction, Stroke), and Hepatic Neoplasia (liver tumors). The risk of thrombotic events is highest during the first year of use.
Safety-Related Restrictions The medicine is contraindicated (must not be used) in individuals with a history of or current thromboembolic disease, known or suspected estrogen-dependent cancers, certain liver diseases, or uncontrolled hypertension.
Population-Specific Risk Smoking significantly increases the risk of serious cardiovascular events, and the medicine is officially contraindicated in smokers over 35 years of age due to this heightened risk.

Regulatory Safety Summary

  • The official safety profile focuses on the potential for rare but critical vascular risks and the incidence of common, less severe adverse reactions affecting multiple bodily systems.
  • Safety documents establish clear constraints by listing specific pre-existing conditions (contraindications) and noting that the risk for certain serious events, such as thromboembolism, is highest during the initial phase of treatment.
  • Official regulatory labeling requires a specific safety warning regarding the elevated cardiovascular risk for smokers, particularly those over 35.

This structure ensures that the officially documented safety information is communicated in a neutral manner, separating frequent, expected effects from rare, high-risk conditions described in government-mandated labeling.

Overdose and Emergency Response

Overdose and When to Seek Help

This section outlines the officially documented manifestations and required emergency actions in the event of an overdose of Kelnor (ethinyl estradiol and etynodiol diacetate), based strictly on government regulatory documents.

Overdose Scope Official Regulatory Statement
Documented Manifestations Overdosage may cause nausea, vomiting, and vaginal bleeding (as withdrawal bleeding) in females.
Emergency Action Required Patients must seek emergency medical attention immediately, or contact a Poison Help Line.
Antidote Information No specific antidote is documented or described in the regulatory prescribing information.
Population-Specific Risk Reports document serious ill effects following the ingestion of large doses by young children.

Official Overdose Statements

The official drug profile is established by explicit statements in regulatory labeling, such as the U.S. Food and Drug Administration (FDA) Prescribing Information. The primary, expected clinical manifestations of an overdose are generally limited to nausea, vomiting, and withdrawal bleeding.

Immediate medical help is required upon suspected overdosage or ingestion of a large dose. This emergency-response instruction is mandatory, and the labeling does not describe supportive procedures like gastric lavage, as the priority is immediate professional medical care. The regulatory documents specifically caution that the pediatric population faces a distinct risk of serious ill effects upon ingesting large quantities.

Therapeutic Uses of Kelnor

Main Uses of Kelnor

Kelnor is a combination hormonal medication primarily used for the prevention of pregnancy. It contains two types of female hormones: an estrogen (ethinyl estradiol) and a progestin (ethynodiol diacetate). When taken as directed, it functions as an oral contraceptive to inhibit ovulation and alter the reproductive environment to prevent fertilization.

Primary Mechanism of Action

This medication works through several biological pathways to provide contraceptive protection:

  • Inhibition of Ovulation: The primary function is to suppress the release of an egg from the ovaries during the menstrual cycle.
  • Cervical Mucus Alteration: It increases the thickness of vaginal fluid, which helps prevent sperm from reaching an egg.
  • Endometrial Changes: It modifies the lining of the uterus, making it less receptive to the implantation of a fertilized egg.

Secondary Benefits and Uses

Beyond its primary use as a contraceptive, healthcare providers may prescribe Kelnor for various gynecological reasons related to hormonal regulation. These secondary benefits are often a result of the stabilization of hormone levels throughout the month.

Menstrual Cycle Regulation

For individuals with irregular cycles, Kelnor can help establish a more predictable monthly pattern. It is often utilized to manage:

  • Heavy Menstrual Bleeding: By thinning the uterine lining, the medication can reduce the volume and duration of menstrual flow.
  • Menstrual Cramps: It can decrease the production of prostaglandins, often resulting in less painful periods.
  • Cycle Consistency: It helps regulate the timing of withdrawal bleeding for those with frequent or infrequent periods.

Management of Hormonal Conditions

The hormonal balance provided by Kelnor may assist in managing other conditions influenced by the menstrual cycle, such as:

  • Acne Treatment: The medication can reduce the activity of sebaceous glands, which may lead to clearer skin in some individuals.
  • Endometriosis Symptoms: By suppressing the monthly growth and shedding of the uterine lining, it may alleviate the pelvic pain associated with endometriosis.
  • Polycystic Ovary Syndrome (PCOS): It is sometimes used to manage the hormonal imbalances and cycle irregularities associated with this condition.

Eligibility and Restrictions for Use

Kelnor (ethynodiol diacetate and ethinyl estradiol) is an oral contraceptive restricted to females of reproductive potential for pregnancy prevention. Its use is determined by official contraindications concerning vascular risk, hormone-sensitive cancer, and liver function.

Contraindicated Populations and Conditions

Use of Kelnor is prohibited in individuals with a high risk of arterial or venous thrombotic diseases. This includes women who smoke and are over 35 years of age, and those with a history of deep vein thrombosis (DVT), pulmonary embolism (PE), stroke, or coronary artery disease. It is also contraindicated in females with known or suspected breast cancer or other estrogen-dependent tumors, undiagnosed abnormal uterine bleeding, or liver tumors/disease.

Age and Physiological Restrictions

  • Age-Related: The medicine is not for use prior to menarche (the first menstrual period). Its use is not established in geriatric patients.
  • Pregnancy/Lactation: Kelnor is contraindicated in pregnancy. It is also not recommended while breastfeeding as it may diminish the quantity and quality of breast milk.
  • Conditional Use: Following delivery, Kelnor should not be started until at least four weeks postpartum due to an elevated risk of thromboembolism. Use must also be discontinued prior to and after major surgery that requires prolonged immobilization.

What should I know about interactions with other medicines?

Kelnor Interactions with other medicines and products

Official regulatory information for Kelnor (Ethinyl Estradiol and Etynodiol Diacetate) documents specific interactions that can affect its efficacy or increase the risk of adverse effects.


Formally Contraindicated Combinations

Kelnor is prohibited for co-administration with certain medicinal products due to unacceptable risks as specified in regulatory labeling.

  • Hepatitis C Virus (HCV) Drug Regimens: Combinations containing Ombitasvir/Paritaprevir/Ritonavir, with or without Dasabuvir, are contraindicated due to the potential for significant increases in liver enzymes (ALT).

Interactions Affecting Efficacy (Enzyme Inducers)

Some medicines can cause hepatic enzyme induction, increasing the clearance of Kelnor's hormonal components and potentially leading to reduced contraceptive efficacy.

Product Category Example Substances
Anticonvulsants Phenytoin, Carbamazepine, Topiramate
Antibiotics/Antifungals Rifampin, Griseofulvin
HIV/AIDS Medications Nelfinavir, Ritonavir
Herbal Products St. John's Wort

Other Significant Exposure-Altering Interactions

Kelnor can also affect the plasma levels of co-administered medicines, increasing the concentration of drugs such as corticosteroids (e.g., Prednisolone) and Theophylline. Conversely, the levels of Lamotrigine are documented to be significantly reduced.


Population and Lifestyle Restrictions

Use is formally contraindicated in females over 35 years of age who smoke, as this combination significantly increases the risk of serious cardiovascular events. Furthermore, the medicine is required to be discontinued at least 4 weeks prior to major surgery associated with high thromboembolism risk.

Mechanism of Action

Kelnor is a selective estrogen receptor modulator (SERM) that exhibits tissue-specific agonist and antagonist activity towards estrogen receptors ( ERalpha and ERbeta). It achieves its effects by binding to the ligand-binding domain of the estrogen receptor, inducing a specific conformational change in the receptor-ligand complex. This altered conformation modulates the recruitment of co-activator and co-repressor proteins at target gene promoters.

In bone tissue, Kelnor acts as an ER agonist, influencing the transcription of genes critical for osteoblast and osteoclast function. Specifically, it alters cellular dynamics related to pathological progression by suppressing osteoclast differentiation and activity. This action influences the balance between bone resorption and formation, affecting the net mineralization rate of bone tissue.

Dosage and Administration Information

Official Administration Guidelines

Kelnor (ethynodiol diacetate and ethinyl estradiol) is an oral tablet regimen taken daily for 28 consecutive days. The administration must be completed precisely as instructed, following the route, dosage, and sequence specified in the official labeling.


Core Dosing and Schedule

Administration Aspect Official Instruction
Route of Administration Oral tablet, taken by mouth
Dosing Frequency One tablet taken daily
Timing Must be taken at the same time every day

The standard 28-day regimen requires taking 21 light yellow (active) tablets first, followed by 7 white (inactive) tablets. After the last inactive tablet, a new pack must be started the next day.


Starting the First Pack

The start of the first pack is defined by two options:

  • Day 1 Start: Take the first active tablet on the first day of the menstrual period.
  • Sunday Start: Take the first active tablet on the first Sunday after the menstrual period begins.

If the medication is started later than Day 1 of the menstrual cycle, a non-hormonal back-up contraceptive method (e.g., condoms) must be used for the first 7 consecutive days of the first cycle.


Missed Active Dose Procedures

If the daily schedule is disrupted, specific steps are required to minimize the risk of failure:

  • Missed 1 Active Tablet: Take the missed tablet as soon as remembered, even if it means taking two tablets on the same day, then continue taking the rest of the pack one per day.
  • Missed 2 or More Active Tablets (Week 1 or 2): Take 2 tablets on the day remembered and 2 tablets the next day. A back-up contraceptive method must be used for the next 7 days. The pack is then continued at one tablet per day.
  • Missed 2 or More Active Tablets (Week 3): The rest of the pack must be thrown out, and a new pack should be started that same day (Day 1 Start) or the following Sunday (Sunday Start). A back-up contraceptive method must be used for the next 7 days.

Recent Clinical Evidence

Research evidence / Overview of Studies for Kelnor

This section provides a summary of the available clinical evidence, derived from official regulatory documents and peer-reviewed scientific literature, concerning the types of studies conducted for Kelnor (Ethinyl Estradiol and Etynodiol Diacetate). The text focuses only on the structure of the research and what it was designed to measure, without offering clinical recommendations or making claims about guaranteed personal outcomes.


Evidence for use in Preventing Pregnancy (Contraception)

Research for Kelnor and other combination oral contraceptives involves studies exploring the rate of unintended pregnancy. Research for this indication has consisted of registrational clinical trials designed to examine the rate of use and associated outcomes, and large-scale observational cohort studies that monitor the experience of thousands of individuals over many years. The main outcome that research examined was the rate of unintended pregnancy, which is commonly calculated using the Pearl Index (a measurement of pregnancies per 100 woman-years of use). Studies also monitor differences between the outcome rates achieved with perfect adherence and the rates seen with typical use in daily life.

Trials describe patterns where failure rate measurements varied in relation to the degree of adherence reported in the study. This evidence contributes to the broader scientific understanding of the method's use in the population.

Evidence for use in Menstrual Cycle Management

Studies have also explored outcomes related to physical discomfort and functional imbalance associated with the menstrual cycle. This area of research is often covered by Randomized Controlled Trials (RCTs) that focus on contraception but include secondary endpoints, or observational studies focused on women experiencing symptoms.

Research has explored outcomes related to physical discomfort. Investigators measured menstrual cycle regularity (e.g., consistency of cycle length) and monitored changes in menstrual blood loss and the occurrence of dysmenorrhea (painful menstruation). These findings describe patterns observed in the studies, where participants reported more consistent and predictable scheduled bleeding across observed cycles.


What is Still Uncertain About the Research Base

While an extensive body of research exists, scientific literature acknowledges several limitations and areas where evidence is still being developed. For instance, real-world compliance is a substantial variable that studies acknowledge can alter the measured rate compared to highly controlled trial settings. The evidence quality varies across studies, particularly between highly controlled clinical trials and large-scale, sometimes less granular, observational studies. Furthermore, long-term comparative data and subgroup findings for specific formulations remain insufficient or limited in certain clinical trials. Research provides context but not individual predictions, and it is important to remember that study results reflect the specific conditions under which they were conducted.

Key Studies & References

  1. Ethynodiol Diacetate and Ethinyl Estradiol Tablets USP, 1 mg/35 mcg (Official Product Labeling)

Frequently Asked Questions (FAQ)

Common questions about Kelnor (FAQ)

Q: What is the main condition Kelnor is approved to treat?

A: According to official regulatory documents, the main approved indication for Kelnor is for the prevention of pregnancy. It is a prescription option used for birth control.


Q: What is the official classification of the drug Kelnor?

A: The drug is officially classified as a Progestin/Estrogen combined contraceptive (COC). This classification describes its composition of two types of hormones used together for birth control.


Q: How does Kelnor compare to other medicines in the same drug class?

A: Kelnor is classified as a monophasic combined oral contraceptive. This means that all of the active tablets in the pack contain the same fixed doses of the two hormones. This differs from multiphasic pills, where hormone levels change throughout the active phase.


Q: What should be clarified about how Kelnor is described in its official mechanism of action?

A: The official mechanism is complex, but the medication works primarily by inhibiting ovulation (egg release), thickening cervical mucus, and thinning the uterine lining to help prevent pregnancy.


Q: Is Kelnor an older or newer type of medicine?

A: While the specific brand name may vary, information suggests that the estrogen component, Ethinyl Estradiol, was granted initial FDA approval in the 1940s, making it a well-established ingredient.


Q: What official organization first approved Kelnor for use?

A: While the specific brand approval date is not immediately available, the estrogen component, Ethinyl Estradiol, was granted initial approval by the FDA (U.S. Food and Drug Administration).


Q: How quickly can someone expect to notice the effects of Kelnor?

A: The primary contraceptive mechanism begins upon administration. However, official guidelines suggest using a non-hormonal back-up method for the first 7 days if the pack is started after the first day of the menstrual cycle.


Q: How long does Kelnor typically need to be taken before its full effects are seen?

A: Regulatory instructions note that if the patient initiates use after Day 1 of the menstrual cycle, a back-up contraceptive method is advised for the first seven consecutive days to support the intended effectiveness.


Q: Does Kelnor carry a Boxed Warning, and what does that mean?

A: The regulatory labeling includes a Boxed Warning that highlights the most serious risks associated with the drug. This warning specifically calls attention to the elevated risk of serious cardiovascular events for women over 35 who smoke.


Q: Can people with liver or kidney issues generally use Kelnor?

A: The labeling specifies exclusion (contraindication) in cases of certain liver diseases or liver tumors. It is noted that the drug is used with caution and careful monitoring in patients with renal dysfunction (kidney problems).


Q: Is Kelnor considered appropriate for use by older adults?

A: The primary age restriction noted in official labeling is for women over 35 who smoke, due to a significantly increased cardiovascular risk. There is no specific guidance regarding older non-smoking women outside of the general contraindications.


Q: Is the use of Kelnor studied in research involving children or adolescents?

A: Official patient guidance specifies an exclusion for use in children who have not yet had their first menstrual period (menarche).


Q: Does Kelnor affect sleep patterns, either causing insomnia or drowsiness?

A: Difficulty sleeping (insomnia) is listed as a potential side effect. Drowsiness, however, is noted in documentation related to accidental overdose symptoms.


Q: Why do some users report that Kelnor made them feel emotionally different?

A: Official prescribing information lists mental/mood changes as possible side effects. These reported changes can include new or worsening depression and nervousness.


Q: Is it common to feel tired or dizzy when first taking Kelnor?

A: Official prescribing information lists both dizziness and tiredness (loss of energy) as possible reported side effects. The possibility exists for such effects to occur, particularly when beginning the medication.


Q: Is it necessary to have routine check-ups or blood tests while on Kelnor?

A: Official guidance notes that annual physical examinations are generally performed for all women using oral contraceptives. These exams typically include blood pressure checks, breast exams, and may involve relevant laboratory tests.


Q: Do regulators require any specific patient monitoring while taking Kelnor?

A: Official monitoring guidelines focus on tracking blood pressure and observing patients for the recurrence or worsening of depression. Specific lab tests may be necessary for patients with certain pre-existing conditions like diabetes.


Q: Does Kelnor cause long-term side effects that people should know about?

A: Official guidance notes that annual physical examinations are considered good medical practice while using the medication. This monitoring covers checks of blood pressure, breast and pelvic organs, and may involve laboratory tests related to lipid and liver function.


Q: Is it true that certain foods can interfere with Kelnor’s absorption?

A: Official prescribing information notes that consuming grapefruit or grapefruit juice while using this medication can increase the level of estrogens in the body.


Q: Are there any known interactions between Kelnor and common over-the-counter pain relievers?

A: Regulatory data notes that the risk or severity of adverse effects may be increased when the generic components of Kelnor are combined with Acetaminophen, a common over-the-counter pain reliever.


Q: Can Kelnor be taken with vitamin supplements or herbal remedies?

A: Official guidance on supplements and herbal remedies should be reviewed with a healthcare provider due to the potential for interactions. Certain herbal products have specific warnings about affecting the drug's efficacy.


Q: Is Kelnor a drug that can be stopped easily or does it require a planned approach?

A: Official guidelines note that discontinuation is necessary at least 4 weeks prior to major surgery associated with high thromboembolism risk. Additionally, the drug is advised to be stopped if depression recurs to a serious degree.


Q: What happens if someone accidentally takes more Kelnor than the usual regimen allows?

A: Overdose symptoms are not typically expected to be life-threatening. Symptoms reported may include nausea, vomiting, breast tenderness, and unusual vaginal bleeding.


Q: Does the official guidance for Kelnor mention any effects on fertility?

A: Guidance for starting the medication mentions that the possibility of ovulation and conception prior to initiation should be considered. Regulatory documents do not detail the long-term impact on fertility after cessation.

How should Kelnor be stored and disposed of?

How to Store and Dispose of Kelnor?

The stability and effectiveness of Kelnor (ethynodiol diacetate and ethinyl estradiol tablets) are maintained by strict adherence to officially documented storage conditions.

Required Storage Conditions

Condition Requirement
Temperature Store at Controlled Room Temperature (20 C to 25 C or 68 F to 77 F).
Protection Keep the container tightly closed and protect the tablets from freezing, excess heat, and moisture.
Child Safety The medication must be kept out of the reach of children and pets.

Official Disposal Instructions

Unused or expired Kelnor must be discarded according to local waste regulations. Patients are advised to consult a healthcare professional for specific instructions on how to properly dispose of any unused medicine.

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

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