Learn about many of the available medications in our database.
levonorgestrel (emergency contraceptive)
How does this medication work? What will it do for me?
Levonorgestrel belongs to the family of medications known as progestins. Progestins are female sex hormones that are used in birth control pills and often in combination with the hormone estrogen.
Levonorgestrel is a progestin-only emergency birth control pill intended for use within 72 hours of unprotected sexual intercourse. It should only be used by women whose regular birth control methods have failed or who may have had intercourse without birth control. It is not a substitute for correct use of regular birth control.
This medication is believed to prevent pregnancy primarily by delaying ovulation or preventing fertilization of the egg. It may also prevent implantation of the egg by altering the endometrium (inner lining of the uterus). It is important to realize that once implantation has occurred and pregnancy is established, levonorgestrel cannot cause an abortion or harm the fetus. No serious complications have been reported with this medication.
This medication reduces the risk of pregnancy among users from around 8% to around 1% after unprotected sexual intercourse. It is most effective in the first 24 hours after intercourse.
It should be noted that this medication does not protect against HIV infection (AIDS) or other sexually transmitted infections.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
Each round, white-to-off-white, uncoated, flat tablet debossed with "251" on one side contains 1.5 mg of levonorgestrel. Nonmedicinal ingredients: colloidal silicon dioxide, corn starch, lactose monohydrate, magnesium stearate, and polyvinyl pyrrolidone K-25.
How should I use this medication?
The 1.5 mg tablet contained in the kit should be taken as soon as possible within 72 hours of unprotected sexual intercourse. The medication is most effective if taken within 12-24 hours of unprotected sexual intercourse.
Because this medication is often associated with nausea, your doctor may also want you to take medication to prevent nausea at the same time as taking these pills. If you vomit within 2 hours of taking the tablet, you should contact your health care provider as you may need to take another dose. This medication can be used at any time during the menstrual cycle. It can be taken with or without food. Taking it with food may help reduce the nausea.
Most women have their expected menstrual period within 7 days of their normal time after using this medication. If you don’t have your menstrual period within 7 days of when it is expected, you should have a pregnancy test done.
Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
It is important to take this medication exactly as recommended by your doctor. Levonorgestrel is not intended to be used routinely as birth control.
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Do not take this medication if you:
- are allergic to levonorgestrel or any ingredients of this medication
- are or may be pregnant
- have undiagnosed abnormal vaginal bleeding
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abdominal pain
- breast tenderness
- irregular, altered, or heavier menstrual bleeding
Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- cramping or severe abdominal pain before your next normal period
- painful menstruation
- skin rash
- vaginal discharge
- very heavy vaginal bleeding
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Decreased effectiveness: This medication may be less effective for women who weigh more than 165 pounds (75 kg) . Regardless of body weight, this medication should be taken as soon after unprotected intercourse as possible to ensure the most reliable outcome. If you weigh more than 165 pounds, you may wish to contact your doctor or pharmacist for advice about emergency contraception.
Diabetes: Although few women have experienced loss of blood glucose control when taking progestin-only pills, women with diabetes should monitor their blood glucose carefully after taking this medication.
Liver problems: The safety of using this medication has not been established for people with liver disease. If you have liver disease, discuss with your doctor whether any special monitoring is needed.
Migraine: After taking a dose of levonorgestrel, you may experience a severe headache or a migraine.
Sexually transmitted infections: This medication does not protect against sexually transmitted infections, including HIV or AIDS. For protection against these infections, latex condoms should be used.
Pregnancy: This medication should not be used during pregnancy. It will not terminate a pregnancy that has already been established.
Breast-feeding: Small amounts of progestin pass into the breast milk of women taking progestin-only pills. No adverse effects have been found with taking this medication while breast-feeding, either in the quality and quantity of milk or in the growth and development of the infant.
What other drugs could interact with this medication?
There may be an interaction between levonorgestrel and any of the following:
- antibiotics (ampicillin, cotrimoxazole, tetracycline, clarithromycin)
- barbiturates (e.g., pentobarbital, phenobarbital)
- diabetes medications (e.g., canagliflozin, glyburide, insulin, metformin, rosiglitazone)
- HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
- low-molecular-weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
- lumacaftor and ivacaftor
- St. John’s wort
- tranexamic acid
Because only one tablet of levonorgestrel is taken, the effects of these medications on how the levonorgestrel works is likely to be minimal. If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.
All material copyright MediResource Inc. 1996 – 2022. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/drug/getdrug/Contingency-One