Kelnor (Ethynodiol Diacetate and Ethinyl Estradiol) - Oral


Smoking cigarettes can increase the risk of serious cardiovascular side effects while using oral contraceptives. People who are especially at risk include heavy smokers (15 or more cigarettes per day) and those over 35. For this reason, people who use oral contraceptives should be strongly advised not to smoke.

What Is Kelnor?

Kelnor is a combined hormonal contraceptive pill. Each pill contains 1 milligram of ethynodiol diacetate and 35 micrograms of ethinyl estradiol. These are synthetic forms of progestin and estrogen, respectively, which are hormones found naturally in your body that regulate your menstrual cycle.

Kelnor works to prevent pregnancy via several mechanisms, including inhibiting ovulation (which means no egg for sperm to fertilize) and thickening your cervical mucus (making it harder for sperm to enter the uterus).

Each pack of Kelnor comes with 21 yellow active pills containing these hormones, taken once daily for 21 days, followed by seven days of white placebo pills that do not have any hormones or active ingredients. The placebo pills are there as reminders so that you stay in the habit of taking one pill at the same time each day.

Kelnor is a prescription product, so your healthcare provider needs to write you an order for it. You will get the drug filled by a pharmacy rather than purchasing it over-the-counter from a drugstore or grocery store.

Drug Facts

Generic Name: Ethynodiol diacetate and ethinyl estradiol

Brand Name: Kelnor, Demulen, Zovia

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: Combined hormonal contraceptive

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Ethynodiol diacetate and ethinyl estradiol

Dosage Form: Tablet

What Is Kelnor Used For?

Kelnor is used to prevent pregnancy. It is a combined hormonal contraceptive (CHC) containing synthetic forms of two types of hormones that your body produces naturally: a progestin and an estrogen. Taking birth control pills each day maintains consistent hormone levels in your body that are sufficient to prevent pregnancy.

Kelnor (Ethinyl Estradiol and Ethynodiol Diacetate) Drug Information - Showing a female reproductive system and a red circle around areas affected

Verywell / Zoe Hansen

How to Take Kelnor

Take one pill from your Kelnor pack at the same time each day. You can take it with or without food, at whatever time you can most easily remember to take it. Taking pills as close to 24 hours apart as possible will ensure the best results and the most stable hormone levels.

Once you’ve taken active pills for 21 days, you’ll reach your placebo pills. You may take one of these white pills each day for all seven days to remain in the habit of taking a daily pill. It is also OK to skip these white pills and not take any for seven days since they do not contain active ingredients.

You will likely experience bleeding during these seven days off of active pills. This is not a true period but rather a “withdrawal bleed” or “pill bleed,” which will probably be shorter and lighter than the periods you experience when not on birth control.

How to Start Your First Pill Pack

You can take your first Kelnor pill as soon as it is prescribed to you. However, depending on the timing of your menstrual period, you may or may not be protected from pregnancy right away.

If you start a pill pack within the first five days of your period, you are protected right away and do not need to use any backup form of birth control during sex.

If you start the pack at any other point in relation to your period, or you’re not sure when your last period was, make sure to use an extra form of birth control like a condom, diaphragm, or cervical cap during sex for the first seven days after starting Kelnor to be protected from pregnancy.


Store Kelnor pill packs at room temperature (between 68 F and 77 F) in an area without too much moisture, away from children and pets.

If you’re traveling by plane, keep Kelnor in your carry-on luggage so that you aren’t separated from it if your checked baggage goes missing. If you’re traveling by car, take care not to leave your pill packs in especially hot or cold temperatures for long periods, like overnight in the car.

Off-Label Uses

Some people may have reasons to use hormonal contraception besides or in addition to preventing pregnancy. It can be used to help control irregular menstrual cycles, treat extremely heavy or painful periods, and improve hormonal acne.

How Long Does Kelnor Take to Work?

Whether or not you are immediately protected from pregnancy while taking Kelnor depends on when you start taking it in relation to your period.
If you take your first pill within the first five days of your period, you’re protected right away and don’t need to use a backup method. If you start the pack any other time, you’ll need to use a backup form of birth control like a condom, diaphragm, or cervical cap during sex for the first seven days.

What Are the Side Effects of Kelnor?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at or 1-800-FDA-1088.

Common Side Effects

The following are some of the more common side effects of using Kelnor. If you notice these side effects and think they are severe or do not go away, you should notify your healthcare provider:

  • Headache or migraine
  • Nausea and vomiting
  • Weight gain
  • Bleeding between withdrawal bleeds (breakthrough bleeding)
  • Painful menstruation, typically involving cramps (dysmenorrhea)
  • Breast tenderness/pain/discomfort
  • Bleeding irregularities, including metrorrhagia (bleeding from the uterus)

Certain side effects are more likely to occur with certain birth control pills, such as pills that contain higher or lower ratios of estrogen and progestin hormones. Give your body a couple of months to adjust to the type you’re trying. If you’re still experiencing difficulty with a specific side effect, you can talk to your healthcare provider about switching to a brand that may be more likely to minimize that side effect.

Severe Side Effects

The main severe side effect of using Kelnor and all combined (estrogen-containing) hormonal contraceptives is the risk of blood clots and other vascular or heart-related events.

Estrogen and its synthetic forms like ethinyl estradiol, found in Kelnor, can make your blood form clots more easily. This can lead to an increased risk of heart attack, stroke, and blood clots. The risk is higher in smokers and individuals older than 35 or those with high blood pressure, high cholesterol, diabetes, or obesity. These events and their symptoms include:

  • Venous thromboembolism (VTE): This is a blood clot that forms in your veins and can block blood flow to your heart. VTEs can be life-threatening if not treated. Symptoms include leg pain or swelling, reddish discoloration, and skin that feels warm to the touch.
  • Myocardial infarction (MI): Also known as a heart attack, symptoms of an MI may include chest discomfort like pressure, squeezing, fullness, or pain. They may also cause discomfort in one or both arms, the back, neck, jaw, or stomach.
  • Stroke: A stroke is another medical emergency that occurs when blood flow to your brain gets cut off or interrupted. Symptoms include drooping in the face, arm weakness, and difficulty speaking or walking.

Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Long-Term Side Effects

The vascular risks described above, such as heart attack, stroke, and blood clots that come with taking CHCs like Kelnor, may increase if you take CHCs over time but do seem to gradually disappear after the drug is stopped.

A couple of other potential risks of long-term birth control use are as follows, but how strongly associated they are with taking birth control long-term is unknown:

  • Gallbladder disease: You may have a greater risk of gallbladder disease or gallstones if you use birth control long-term.
  • Liver tumors: Birth control may rarely cause benign but dangerous liver tumors that have the potential to rupture and cause internal bleeding.

The effect of hormonal contraceptives on fertility, or the ability to get pregnant, is a highly discussed topic, and many misconceptions exist. While hormonal birth control is designed to lower your fertility while you take it (so you don’t get pregnant), your fertility will most often return to normal within a matter of weeks to months after stopping the pill.

Report Side Effects

Kelnor may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Kelnor Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Your doctor may ask you to begin your dose on the first day of your menstrual period (called Day 1 start) or on the first Sunday after your menstrual period starts (called Sunday start). When you begin on a certain day it is important that you follow that schedule, even if you miss a dose. Do not change your schedule on your own. If the schedule that you use is not convenient, talk with your doctor about changing it. For a Sunday start, you need to use another form of birth control (eg, condom, diaphragm, spermicide) for the first 7 days.

You should begin your next and all subsequent 28-day regimens of therapy on the same day of the week as the first regimen began and follow the same schedule.

  • For oral dosage form (tablets):
    • For contraception (to prevent pregnancy):
      • Adults and teenagers—One light yellow tablet (active) taken at the same time each day for 21 consecutive days followed by one white (inert) tablet daily for 7 days per menstrual cycle.
      • Children—Use and dose must be determined by your doctor.


Kelnor is indicated for individuals of reproductive age who have started having periods. It can be used safely and effectively in people younger than 18 who have started having periods but not before. Kelnor has not been studied and should not be used in people who have reached menopause.

If you are pregnant, stop taking Kelnor since there is no reason to take hormonal contraceptives while pregnant. Studies have not found a higher risk of birth defects after exposure to hormonal contraceptives during early pregnancy, so don’t panic if you find out you are pregnant but haven’t stopped taking birth control yet.

If you are breastfeeding, wait until your baby is completely weaned before starting or restarting birth control to avoid exposing them to oral contraceptives. Small amounts of contraceptive hormones have been identified in breast milk, and they may also interfere with the quality and quantity of a mother's milk production.

Missed Dose

What to do if you miss birth control pills can become somewhat complicated, but no need to panic. Keep in mind these instructions apply to active pills (the yellow pills) in Kelnor. If you miss placebo pills, you don’t need to do anything. Just make sure you do not take more than seven days off of the active pills.

If you miss one pill, just take it as soon as you remember. This may mean taking two pills on the same day or at the same time. You don’t need to use a backup method if you have sex.

If you miss two pills in week one or week two of your pack, take two pills on the day you remember and two pills the following day. Then take one pill daily as usual until you finish the pack. In this case, you need to use a backup method of birth control for the seven days after you miss pills.

If you miss two pills in week three of your pack OR if you miss three or more pills in a row at any point in the pack and are a day one starter (meaning you started the pack on the first day of your period), throw away the rest of your pack and start a new pack the same day. Take one pill daily as usual. Use a backup birth control method during sex for the next seven days.

If you miss two pills in week three of your pack OR if you miss three or more pills in a row at any point in the pack and are a Sunday starter (meaning you started the pack on a Sunday), keep taking one pill every day until Sunday. Throw out the rest of the pack on that Sunday and start a new pack of pills the same day. Use a backup birth control method during sex for the next seven days.

In these last two scenarios, you may not have a withdrawal bleed that month. But if you miss two withdrawal bleeds in a row during your placebo weeks, call your healthcare provider as you may be pregnant.

Overdose: What Happens If I Take Too Much Kelnor?

If you are using Kelnor as directed, meaning you’re taking one pill per day and you are not taking another form of hormonal birth control at the same time, it is basically impossible to overdose. Taking too many pills at one time may cause nausea and withdrawal bleeding.

What Happens If I Overdose on Kelnor?

If you think you or someone else may have overdosed on Kelnor, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or experiences signs of an overdose after taking Kelnor, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly and does not cause unwanted effects. Your doctor may also want to check your blood pressure while taking this medicine.

Although you are using this medicine to prevent pregnancy, you should know that using this medicine while you are pregnant could harm your unborn baby. If you think you have become pregnant while using the medicine, tell your doctor right away. Make sure your doctor knows if you had given birth within 4 weeks before you start using this medicine.

If you suspect that you may be pregnant, stop using this medicine and check with your doctor right away. You may have a higher risk of an ectopic pregnancy if you get pregnant while using this medicine. An ectopic pregnancy can be a serious and life-threatening condition. It can also cause problems that may make it harder for you to become pregnant in the future.

Do not use this medicine together with medicine to treat hepatitis C virus infection, including ombitasvir/paritaprevir/ritonavir, with or without dasabuvir (Technivie®, Viekira Pak®).

This medicine will not protect you from getting HIV/AIDS, herpes, or other sexually transmitted diseases. Tell your doctor if you or your partner begin to have sexual intercourse with other people, or you or your partner tests positive for a sexually transmitted disease. If this is a concern for you, talk with your doctor.

You might have some light bleeding or spotting when you first start using this medicine. This is usually normal and should not last long. However, if you have heavy bleeding or the bleeding lasts more than a few days in a row, call your doctor.

Do not use this medicine if you smoke cigarettes or if you are over 35 years of age. If you smoke while using ethinyl estradiol and norgestrel combination, you increase your risk of having a blood clot, heart attack, or stroke. Your risk is even higher if you are over age 35, if you have diabetes, high blood pressure, high cholesterol, or if you are overweight. Talk with your doctor about ways to stop smoking. Keep your diabetes under control. Ask your doctor about diet and exercise to control your weight and blood cholesterol level.

Using this medicine may increase your risk of having blood clotting problems. Check with your doctor right away if you have pain in the chest, groin, or legs, especially the calves, difficulty with breathing, a sudden, severe headache, slurred speech, a sudden, unexplained shortness of breath, a sudden loss of coordination, or vision changes while using this medicine.

Using this medicine may increase your risk of having cancer of the breast or your reproductive organs (eg, endometrium, ovaries, cervix). Talk with your doctor about this risk. Check with your doctor right away if you experience abnormal vaginal bleeding.

Check with your doctor right away if you have pain or tenderness in the stomach, dark urine, pale stools, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Check with your doctor immediately if blurred vision, difficulty in reading, or any other change in vision occurs during or after treatment. Your doctor may want an eye doctor (ophthalmologist) to check your eyes.

This medicine may increase your risk of having gallbladder disease. Check with your doctor if you start to have stomach pains, nausea, and vomiting.

Make sure any doctor or dentist who treats you knows that you are using this medicine. The results of some medical tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn't Take Kelnor?

You should not take Kelnor if any of the following applies to you:

  • You are at high risk for blood clots, such as if you are a smoker over age 35, have a current or history of blood clots, uncontrolled high blood pressure, or have diabetes and are over age 35
  • If you get migraine headaches with aura (which causes a change in your vision), or are over age 35 with any migraine headaches
  • If you currently have or have a history of breast cancer
  • If you have any liver disease, such as tumors, hepatitis, or cirrhosis (scarring of the liver that is usually permanent)
  • If you have abnormal uterine bleeding (menorrhagia) that hasn’t been addressed by a healthcare provider
  • If you have chest pain that hasn’t been addressed by a healthcare provider

What Other Medications Interact With Kelnor?

There are a few drugs that can interrupt how well Kelnor works and vice versa.

Drugs that may decrease your exposure to Kelnor, thereby lowering its effectiveness, include:

  • Barbiturates like phenobarbital and secobarbital
  • Drugs used to prevent seizures (anticonvulsants), such as Tegretol (carbamazepine), Lamictal (lamotrigine), and Dilantin (phenytoin)
  • Fulvin P/G, Fulvin-U/F, Gris-PEG (griseofulvin), a drug used to treat fungal infections
  • Rifampin, an antibiotic used to treat tuberculosis
  • Products containing St. John’s Wort, a plant that is often marketed to treat depression and other mental health conditions

Drugs that may not work as well because of Kelnor include:

  • Lamotrigine
  • Thyroid hormone or corticosteroid replacement therapy, such as levothyroxine, prednisone, or dexamethasone
  • Painkillers like Tylenol (acetaminophen) and morphine
  • Restoril (temazepam), a drug used for anxiety and sleep

Finally, you should avoid Kelnor completely if you are taking medications for hepatitis C containing ombitasvir/paritaprevir/ritonavir, with or without dasabuvir. Some brand names that contain these drugs are Viekira Pak and Technivie, both discontinued regimens. Using these while taking Kelnor increases the risk for alanine aminotransferase (ALT) elevations. ALA is an enzyme that can indicate problems with your liver.

What Medications Are Similar to Kelnor?

Many types of birth control exist that work similarly to Kelnor. There are hormonal and non-hormonal options. Among the hormonal options, there are progestin-only contraceptives and combined hormonal contraceptives, like Kelnor and the following:

  • Zovia 1/35E contains the same progestin and estrogen hormones as Kelnor at the same ratio.
  • Ethynodiol 1/50 contains the same progestin and estrogen hormones as Kelnor but with a higher estrogen level.
  • Nortrel 0.5/35 contains the same amount of estrogen as Kelnor but a different progestin hormone called norethindrone.
  • Femynor is another product that contains 35 micrograms of estrogen-like Kelnor but uses a progestin called norgestimate.

This list is NOT a list of drugs recommended to take with Kelnor. You should not take these drugs together. Ask your pharmacist or a healthcare provider if you have questions.

Frequently Asked Questions

  • How does Kelnor work?

    Kelnor is a pill taken daily containing 1 milligram of ethynodiol, a progestin hormone, and 35 micrograms of synthetic estrogen called ethinyl estradiol. These hormones prevent pregnancy by preventing ovulation and thickening cervical mucus.

  • What are the side effects of Kelnor?

    The most common side effects of hormonal birth control, like Kelnor, include headache, nausea or vomiting, breakthrough bleeding, abdominal pain, and breast tenderness.

  • What drugs should not be taken with Kelnor?

    Some drugs may make Kelnor less effective at preventing pregnancy. Anticonvulsant drugs (seizure drugs) and some antibiotics like rifampin are a couple of examples. You may need to use a backup method of birth control while on these drugs.

How Can I Stay Healthy While Taking Kelnor?

Deciding to start taking birth control and which birth control option is the best fit for you is a very personal choice. Sometimes, finding an effective option convenient for you with the fewest side effects can require trial and error. Whichever form you decide on, the most important thing is that you fully understand how it works and how to take it. This will be your best bet at preventing an unwanted pregnancy.

Don’t be embarrassed to ask your healthcare provider anything you do not understand about a particular method of birth control. Any question you have has been asked of them many times before. You have the power to make your own choices regarding your sexual and reproductive health.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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