Loading...
Loading...
Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Plan B One-step
Generic Name
Levonorgestrel
Active Ingredient
LevonorgestrelCategory
Progestin [EPC]
Variants
3
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 1.5 mg/1 | TABLET | ORAL | 50090-5978 |
| 1.5 mg/1 | TABLET | ORAL | 69536-162 |
| 1.5 mg/1 | TABLET | ORAL | 69536-146 |
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Plan B One-step, you must consult a qualified healthcare professional.
Detailed information about Plan B One-step
Levonorgestrel is a potent synthetic progestin used in emergency contraception, long-term intrauterine systems, and oral contraceptive pills to prevent pregnancy by inhibiting ovulation and altering cervical mucus.
The dosage of levonorgestrel varies significantly based on the intended use and the delivery system chosen by the patient and their healthcare provider.
For emergency contraception, the standard adult dose is a single 1.5 mg tablet taken as soon as possible after unprotected intercourse. Clinical studies show that efficacy is highest when taken within 24 hours, though it remains effective up to 72 hours. Some providers may suggest use up to 120 hours (5 days) off-label, though efficacy drops significantly after 72 hours. Alternatively, a two-dose regimen of 0.75 mg taken 12 hours apart may be used.
In combined oral contraceptives, levonorgestrel is typically dosed at 0.1 mg to 0.15 mg daily, often in a 21-day active/7-day placebo cycle. In progestin-only pills ('mini-pills'), a lower dose (e.g., 0.03 mg) is taken every single day at exactly the same time without a break.
These are clinical procedures where a device is inserted into the uterus. The initial release rates vary: Mirena releases approximately 20 mcg/day, while smaller devices like Skyla release about 14 mcg/day. These devices are replaced every 3 to 8 years depending on the specific brand and indication.
Levonorgestrel is generally considered safe and effective for use in post-menarcheal female adolescents (those who have started their periods). The dosage for emergency contraception in adolescents is the same as the adult dose (1.5 mg). For long-term contraception, the use of IUDs in 'nulliparous' adolescents (those who have never given birth) is supported by the American College of Obstetricians and Gynecologists (ACOG). It is not indicated for use before the onset of menses.
No specific dosage adjustments are provided in the manufacturer's labeling for patients with renal impairment. Because levonorgestrel is primarily metabolized by the liver, significant accumulation is not typically expected in those with decreased kidney function, though caution is always advised.
Levonorgestrel is contraindicated in patients with acute liver disease or liver tumors. Because the liver is the primary site of metabolism, impaired hepatic function can lead to increased systemic levels of the hormone, potentially increasing the risk of side effects.
Levonorgestrel is not indicated for use in postmenopausal women, except in specific cases of hormone replacement therapy where it is used to prevent endometrial hyperplasia. It is not intended for use in the geriatric population for contraceptive purposes.
If you miss a dose of a daily levonorgestrel-containing pill, take it as soon as you remember. If you are more than 3 hours late for a progestin-only pill, or if you miss an entire day of a combined pill, you must use a backup method of birth control (like condoms) for the next 48 hours to 7 days, depending on the specific product instructions. Consult your patient information leaflet for the 'missed pill' rules specific to your brand.
Symptoms of a levonorgestrel overdose may include severe nausea, vomiting, and unexpected vaginal bleeding (withdrawal bleeding). While levonorgestrel is not associated with life-threatening acute toxicity, you should contact the Poison Control Center or seek emergency medical attention if a large amount is ingested, particularly by a child.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance.
Most patients taking levonorgestrel, particularly for emergency contraception, experience mild to moderate side effects that typically resolve within 48 to 72 hours. Common reactions include:
Levonorgestrel is a highly effective contraceptive, but it is not suitable for everyone. Before using any form of levonorgestrel, it is vital to disclose your full medical history to your healthcare provider. This medication does not protect against HIV infection (AIDS) or other sexually transmitted infections (STIs). Patients should continue to use barrier protection (condoms) if STI protection is required.
There are no specific FDA black box warnings for levonorgestrel when used as a progestin-only medication (e.g., emergency contraception or IUDs). However, when levonorgestrel is combined with estrogen in birth control pills, the following warning applies:
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive (COC) use. This risk increases with age, particularly in women over 35 years of age, and with the number of cigarettes smoked. For this reason, COCs are contraindicated in women who are over 35 years of age and smoke.
While few drugs are strictly contraindicated, the use of Ulipristal acetate (another form of emergency contraception, brand name Ella) alongside levonorgestrel is generally avoided. Because both drugs target the progesterone receptor, they may interfere with each other's efficacy if taken within 5 days of one another. Taking both can potentially reduce the effectiveness of both medications, increasing the risk of unintended pregnancy.
Most serious interactions involve drugs that induce hepatic enzymes, specifically the CYP3A4 system. These 'enzyme inducers' speed up the metabolism of levonorgestrel, significantly lowering its concentration in the blood and potentially leading to contraceptive failure.
In clinical practice, absolute contraindications are conditions where the risk of using levonorgestrel clearly outweighs any possible benefit. Levonorgestrel must NEVER be used in the following scenarios:
Levonorgestrel is not indicated for use during an established pregnancy. However, extensive epidemiological studies have shown that accidental use of levonorgestrel (specifically for emergency contraception) during early pregnancy does not increase the risk of birth defects, miscarriage, or other adverse fetal outcomes. It is not an abortifacient and will not interrupt a pregnancy that has already implanted. If you become pregnant while an IUD is in place, the device should be removed immediately by a professional to reduce the risk of infection and miscarriage.
Levonorgestrel is excreted in breast milk. However, at the doses used for contraception, it is generally considered safe for nursing infants. The World Health Organization (WHO) and ACOG suggest that progestin-only methods (like the 'mini-pill' or IUD) are the preferred hormonal choice for breastfeeding mothers because they do not interfere with milk production as estrogen-containing pills might. Most guidelines recommend waiting 6 weeks postpartum before inserting an IUD to reduce the risk of uterine perforation.
Safety and efficacy have been established in females of reproductive age. Use before the onset of puberty (menarche) is not indicated. In adolescents, levonorgestrel is a first-line recommendation for both emergency and long-term contraception due to its high efficacy rate and the reduction of 'user error' associated with IUDs.
Levonorgestrel is a potent agonist of the progesterone receptor. Once bound, the receptor-ligand complex translocates to the cell nucleus, where it binds to specific DNA sequences known as progesterone response elements. This modulates the transcription of various genes involved in the reproductive cycle. Its primary contraceptive effect is the suppression of the mid-cycle surge of Luteinizing Hormone (LH) from the anterior pituitary, which prevents the rupture of the ovarian follicle and the subsequent release of an egg (ovulation). It also increases the viscosity of cervical mucus by altering the glycoprotein structure, creating a 'sperm-hostile' environment.
The pharmacodynamic effect of levonorgestrel is dose-dependent. At low doses (e.g., in the mini-pill), it may not consistently inhibit ovulation in all women but still prevents pregnancy via mucus changes. At higher doses (e.g., emergency contraception), it is highly effective at blocking the LH surge if taken before it begins. It also has mild androgenic activity, which accounts for some side effects like acne or changes in lipid profiles.
| Parameter | Value |
Common questions about Plan B One-step
Levonorgestrel is primarily used as a hormonal contraceptive to prevent unintended pregnancy. It is the active ingredient in many 'morning-after' emergency contraceptive pills, where it works by delaying or stopping ovulation. It is also used in long-term intrauterine systems (IUDs) like Mirena to provide birth control for several years and to treat heavy menstrual bleeding. Additionally, it is a common component in daily oral contraceptive pills, often combined with estrogen. Your healthcare provider may also prescribe it off-label for conditions like endometriosis or as part of hormone replacement therapy.
The most common side effects, particularly with emergency use, include nausea, abdominal pain, fatigue, and headache. Many women also experience changes in their next menstrual period, such as it being earlier or later than expected, or having heavier or lighter flow. Dizziness and breast tenderness are also frequently reported shortly after taking the medication. These symptoms are usually mild and typically resolve within a few days without medical intervention. If you experience severe vomiting within two hours of taking the pill, you should contact a doctor to see if a repeat dose is needed.
There is no known direct interaction between alcohol and levonorgestrel that reduces the drug's effectiveness. However, consuming large amounts of alcohol can lead to nausea and vomiting. If you vomit within two hours of taking an emergency contraceptive dose of levonorgestrel, the medication may not have been fully absorbed, which could lead to contraceptive failure. Furthermore, alcohol can impair judgment, potentially leading to further instances of unprotected intercourse. It is generally best to avoid excessive alcohol when taking emergency medications to ensure they are tolerated well.
Levonorgestrel is not intended for use during pregnancy and should not be taken if you know you are already pregnant. However, if you take an emergency contraceptive pill and it fails, or if you were already pregnant without knowing it, research indicates that the hormone does not harm the developing fetus or increase the risk of birth defects. It is not an abortifacient and will not end an existing pregnancy. If you become pregnant while using a levonorgestrel IUD, you must see a doctor immediately to have the device removed, as leaving it in place can cause serious complications like infection or miscarriage.
When used for emergency contraception, levonorgestrel begins working within hours to suppress the LH surge and prevent ovulation. However, its effectiveness is highly time-sensitive; it is most effective the sooner it is taken after unprotected intercourse. For daily progestin-only pills, it typically takes about 48 hours for the cervical mucus changes to become fully effective. For intrauterine systems (IUDs), they are effective immediately if inserted during the first seven days of your menstrual cycle; otherwise, a backup method is needed for the first week. Always follow the specific 'start' instructions provided by your healthcare provider.
Yes, you can stop taking levonorgestrel at any time, but you should be aware that your protection against pregnancy will cease almost immediately. Unlike some other medications, there is no need to 'taper' off the dose. If you stop taking daily pills or have an IUD removed, your fertility will typically return to its normal state within your next cycle. If you do not wish to become pregnant, you should begin using another form of contraception immediately upon stopping levonorgestrel. Some women may experience temporary 'withdrawal bleeding' or spotting after stopping the hormone.
If you miss a dose of a daily levonorgestrel pill, take it as soon as you remember. For progestin-only pills (POPs), being more than 3 hours late is considered a missed dose and requires you to use backup contraception (like condoms) for the next 48 hours. For combined oral contraceptives, the 'missed pill' rules depend on how many pills were missed and where you are in your cycle; generally, missing one pill requires taking it immediately, while missing two or more requires backup contraception for 7 days. Always consult the specific patient information leaflet for your brand or call your pharmacist for guidance.
Clinical studies on the link between levonorgestrel and weight gain have shown mixed results, but most large-scale reviews suggest that any weight change is typically minimal. While some patients report weight gain while using the IUD or daily pills, it is often difficult to distinguish between drug-induced changes and natural fluctuations or lifestyle factors. Progestins can sometimes cause temporary fluid retention or increased appetite in some individuals. If you are concerned about significant weight changes, discuss alternative contraceptive options with your healthcare provider to find the best fit for your body.
Levonorgestrel can interact with several other medications, particularly those that affect liver enzymes. Drugs used to treat epilepsy (like carbamazepine), tuberculosis (like rifampin), and HIV can make levonorgestrel less effective by speeding up its breakdown in the body. The herbal supplement St. John's Wort also significantly reduces its efficacy. Because these interactions can lead to unintended pregnancy, it is crucial to tell your doctor about all medications and supplements you are using. They may suggest a non-hormonal contraceptive option, such as a copper IUD, to avoid these interactions.
Yes, levonorgestrel is widely available as a generic medication, which is typically much more affordable than brand-name versions. Generic versions of the 1.5 mg emergency contraceptive pill (such as My Way, Take Action, or Option 2) are therapeutically equivalent to the brand-name Plan B One-Step. Many daily birth control pills containing levonorgestrel are also available as generics. However, the intrauterine systems (like Mirena or Kyleena) are currently only available as brand-name products due to the complexity of the delivery device. Your pharmacist can help you determine if a generic version of your specific prescription is available.
Other drugs with the same active ingredient (Levonorgestrel)
> Warning: Stop taking Levonorgestrel and call your doctor immediately if you experience any of these.
With prolonged use of levonorgestrel (such as IUDs or daily pills), the most significant long-term effect is a change in menstrual patterns. Many patients experience 'amenorrhea' (the complete absence of periods) after one year of IUD use. While medically harmless, this can be a significant change for patients. There is also ongoing research into the long-term effects of progestins on bone mineral density and mood disorders, though levonorgestrel is generally considered to have a favorable safety profile compared to older progestins.
No FDA black box warnings currently exist for levonorgestrel-only products (like Plan B or Mirena). However, combined oral contraceptives that contain levonorgestrel plus estrogen carry a black box warning regarding Cigarette Smoking and Serious Cardiovascular Events. Smoking increases the risk of serious cardiovascular side effects from combination hormonal contraceptives, including myocardial infarction (heart attack) and stroke. This risk increases with age (especially over 35) and with the number of cigarettes smoked.
Report any unusual symptoms to your healthcare provider.
For patients using long-term levonorgestrel delivery systems (IUDs or implants), regular clinical follow-ups are necessary. This typically includes:
Levonorgestrel is not known to impair the ability to drive or operate heavy machinery. However, if a patient experiences dizziness or fatigue (common after emergency contraception), they should wait until these symptoms subside before engaging in such activities.
There is no direct contraindication between alcohol and levonorgestrel. However, alcohol can increase the likelihood of vomiting. If a patient vomits shortly after taking an emergency contraceptive pill, the drug may not have been absorbed, leading to contraceptive failure.
Levonorgestrel does not require a tapering period. When a daily pill is stopped or an IUD is removed, fertility typically returns to the patient's baseline very quickly, often within the first cycle. Patients should be aware that they can become pregnant immediately after stopping the medication.
> Important: Discuss all your medical conditions with your healthcare provider before starting Levonorgestrel.
Levonorgestrel may affect the results of certain laboratory tests, including:
If you must take an enzyme-inducing medication (like an anti-seizure drug or Rifampin) while needing contraception, your doctor may recommend a non-hormonal method, such as a copper IUD, or a higher dose of the progestin if appropriate. For emergency contraception, some guidelines suggest doubling the dose of levonorgestrel (to 3 mg) if the patient has used an enzyme inducer in the last 4 weeks, though this is an off-label recommendation.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking.
These conditions require a careful risk-benefit analysis by a healthcare provider:
Patients who have had allergic reactions to other 19-nortestosterone derivatives (such as norethindrone or norgestrel) may be at an increased risk of cross-sensitivity to levonorgestrel. Always inform your allergist of your contraceptive history.
> Important: Your healthcare provider will evaluate your complete medical history before prescribing Levonorgestrel.
There is no indication for the use of levonorgestrel in the geriatric population (typically defined as those over 65). It is not used for contraception in postmenopausal women. In rare cases, it may be used as part of a hormone replacement therapy (HRT) regimen in younger postmenopausal women to protect the endometrium.
There is limited data on the use of levonorgestrel in patients with significant renal impairment. However, since the drug is primarily cleared by hepatic metabolism, it is generally used without dose adjustment in these populations. Monitoring for fluid retention (a rare side effect of progestins) is advised.
Levonorgestrel is contraindicated in patients with significant hepatic impairment. In patients with mild hepatic issues, the drug should be used with extreme caution, and liver function tests (LFTs) should be monitored. If LFTs worsen, the medication should be discontinued immediately.
There is some clinical evidence suggesting that the efficacy of levonorgestrel emergency contraception may be reduced in patients with a Body Mass Index (BMI) of 30 kg/m² or greater. While the FDA currently maintains that it is safe and effective for all women, some clinical guidelines suggest that a copper IUD or the drug Ulipristal acetate may be more effective choices for individuals with obesity.
> Important: Special populations require individualized medical assessment.
| Bioavailability | ~90% to 100% |
| Protein Binding | 98% (SHBG and Albumin) |
| Half-life | 24 to 45 hours |
| Tmax | 1.6 to 2.0 hours |
| Metabolism | Hepatic (CYP3A4) |
| Excretion | Renal (45%), Fecal (32%) |
Levonorgestrel is classified as a second-generation progestin. It is more potent than first-generation progestins (like norethindrone) and has a different side effect profile than third-generation (desogestrel) or fourth-generation (drospirenone) progestins, particularly regarding the risk of blood clots, which is generally lower for levonorgestrel-based formulations.