Comprehensive Guide to Levonorgestrel: Uses, Dosage, Side Effects, and More

What is Levonorgestrel?

Overview of Levonorgestrel

Generic Name: Levonorgestrel

Brand Name: Plan B One-Step, Mirena, Kyleena, generics

Drug Group: Progestin (contraceptive, emergency contraception)

Commonly Used For

• Prevent pregnancy after unprotected intercourse.
• Provide long-term contraception via IUD.
• Manage heavy menstrual bleeding.

Key Characteristics

Form: Oral tablets (0.75 mg, 1.5 mg), intrauterine devices (52 mg, 19.5 mg), or implants (detailed in Dosage section).

Mechanism: Suppresses gonadotropin release, preventing ovulation and fertilization.

Approval: FDA-approved (1999 for Plan B) and EMA-approved for contraception.

Indications and Uses of Levonorgestrel

Levonorgestrel is indicated for a variety of reproductive health conditions, leveraging its potent progestogenic effects:

Emergency Contraception: Prevents pregnancy within 72–120 hours after unprotected sex, per gynecology guidelines, supported by clinical trials showing 85–95% efficacy when taken within 24 hours.

Long-Term Contraception: Provides up to 3–8 years of pregnancy prevention via IUD (Mirena, Kyleena), recommended in family planning protocols with evidence of reduced unintended pregnancies.

Heavy Menstrual Bleeding (HMB): Manages menorrhagia by reducing menstrual blood loss, improving quality of life, with gynecologic data.

Endometriosis: Investigated off-label to alleviate pelvic pain and lesion progression, with reproductive endocrinology studies.

Dysmenorrhea: Used off-label to reduce painful periods, supported by pain management research.

Hormone Replacement Therapy (HRT): Applied off-label in postmenopausal women with a uterus, with endocrinology evidence.

Polycystic Ovary Syndrome (PCOS): Explored off-label to regulate cycles and reduce androgen levels, with endocrinology-gynecology data.

Postpartum Contraception: Initiated off-label via IUD insertion post-delivery, with obstetrics studies.

Ovarian Cyst Prevention: Investigated off-label to reduce functional cyst formation, with gynecologic research.

Adenomyosis: Managed off-label to decrease uterine pain and bleeding, with imaging-supported evidence.

Dosage of Levonorgestrel

Dosage for Adults

Emergency Contraception:

• Oral: 1.5 mg as a single dose or 0.75 mg within 72 hours followed by another 0.75 mg 12 hours later, taken within 120 hours of unprotected intercourse.

Long-Term Contraception (IUD):

• Mirena (52 mg): Inserted into the uterus, effective for up to 8 years.
• Kyleena (19.5 mg): Inserted, effective for up to 5 years.

Heavy Menstrual Bleeding:

• Mirena (52 mg): Inserted, reduces bleeding within 3–6 months, maintained for up to 5 years.

Dosage for Adolescents (≥15 years)

Emergency Contraception: Oral: 1.5 mg as a single dose, under gynecologic supervision.

Long-Term Contraception: Mirena or Kyleena: Inserted with parental consent and monitoring.

Dosage for Pregnant Women

Pregnancy Category X: Contraindicated if pregnancy is confirmed; consult an obstetrician for removal if IUD is in place, with fetal monitoring if exposure occurs.

Dosage Adjustments

Renal Impairment: No adjustment needed; monitor for systemic effects in severe cases.

Hepatic Impairment: Mild to moderate (Child-Pugh A or B): Use cautiously; severe (Child-Pugh C): Avoid due to metabolism concerns.

Concomitant Medications: Adjust if combined with enzyme inducers (e.g., rifampin), reducing efficacy; monitor.

Elderly: Not typically indicated; assess for contraindications if used.

Body Weight: Efficacy may decrease in women >75 kg for emergency use; consider copper IUD as an alternative.

Additional Considerations

• Take this active ingredient orally with or without food for emergency use; IUD insertion requires a trained provider.
• Check IUD strings monthly to ensure proper placement.
• Use backup contraception for 7 days after emergency use if ovulation is possible.

How to Use Levonorgestrel

Administration:

• Oral: Swallow tablet whole with water, taken as soon as possible after unprotected sex.
• IUD: Inserted by a healthcare provider into the uterine cavity using a sterile technique.

Timing: Take emergency dose within 120 hours; IUD provides continuous release over years.

Monitoring: Watch for abdominal pain, irregular bleeding, or signs of infection (e.g., fever); report changes immediately.

Additional Tips:

• Store at 20–25°C (68–77°F), protecting from light and moisture.
• Keep out of reach of children; dispose of unused tablets per local regulations.
• Educate patients on IUD removal signs (e.g., expulsion, pain) and emergency contact protocols.
• Schedule follow-up visits at 4–6 weeks post-IUD insertion and annually to assess placement and side effects.
• Avoid douching or using tampons immediately after IUD insertion to reduce infection risk.

Contraindications for Levonorgestrel

Hypersensitivity: Patients with a known allergy to Levonorgestrel or IUD components.

Pregnancy: Contraindicated if pregnancy is confirmed due to teratogenic risk.

Undiagnosed Abnormal Uterine Bleeding: Avoid until etiology is determined to prevent masking serious conditions.

Breast Cancer: Contraindicated in current or recent breast cancer due to hormonal stimulation risk.

Liver Tumors or Disease: Avoid in active hepatic adenoma or severe liver disease (Child-Pugh C).

Uterine Abnormalities: Contraindicated in distorted uterine cavity or acute pelvic inflammatory disease (PID).

Recent Septic Abortion: Avoid within 3 months due to infection risk.

Congenital Heart Disease: Contraindicated in patients with Eisenmenger syndrome due to hemodynamic concerns.

Side Effects of Levonorgestrel

Common Side Effects

• Irregular Bleeding (20–30%, stabilizes over months)
• Abdominal/Pelvic Pain (10–20%, managed with rest)
• Headache (5–15%, relieved with hydration)
• Nausea (5–10%, decreases with food)
• Breast Tenderness (3–8%, subsides with time)

These effects may subside with adaptation.

Serious Side Effects

Additional Notes

• Regular monitoring with pelvic exams and ultrasound every 6–12 months is advised for IUD users.
• Patients with a history of depression should be watched for mood changes, with psychiatric referral if needed.
• Report any unusual symptoms (e.g., severe pelvic pain, chest pain) immediately to a healthcare provider.
• Long-term IUD use (>5 years) requires assessing for expulsion or embedment with imaging.

Warnings & Precautions for Levonorgestrel

General Warnings

Ectopic Pregnancy: Increased risk if pregnancy occurs; monitor for abdominal pain or missed periods.

Ovarian Cysts: Risk of functional cysts with IUD use; perform pelvic exams if suspected.

Uterine Perforation: Rare risk during IUD insertion; assess post-procedure.

Infection: Risk of PID within first 20 days post-IUD insertion; monitor for fever or discharge.

Mood Changes: Risk of depression or anxiety; assess mental health.

Additional Warnings

Thromboembolic Disorders: Rare risk; discontinue if sudden chest pain or leg swelling occurs.

Liver Function: Risk of enzyme elevation; monitor in hepatic impairment.

Breast Tenderness: Common side effect; reassure patients.

Weight Gain: Possible with long-term use; monitor BMI.

Hypersensitivity Reactions: Rare anaphylaxis; stop if severe.

Use in Specific Populations

• Pregnancy: Category X; remove IUD if pregnancy occurs.
• Breastfeeding: Use caution; monitor infant for hormonal effects.
• Elderly: Not typically indicated; assess risks if used.
• Adolescents: Safe for IUD with consent and monitoring.
• Renal/Hepatic Impairment: Adjust or avoid in severe cases.

Additional Precautions

• Inform your doctor about liver disease, recent pregnancy, or bleeding disorders before starting this medication.
• Avoid smoking to reduce thrombotic risk during IUD use.
• Use condoms if STI risk is present to complement IUD protection.

Overdose and Management of Levonorgestrel

Overdose (from excessive oral intake) may cause:

• Nausea, vomiting, or vaginal bleeding.
• Severe cases: Hormonal overload (e.g., breast tenderness, dizziness) or liver strain.
• Abdominal pain or fatigue as early signs.
• Rare coma or profound hormonal imbalance with extremely high doses.

Immediate Actions

Contact the Medical Team: Seek immediate medical help if overdose is suspected.

Supportive Care: Monitor vital signs, provide antiemetics if needed, and observe for 24 hours.

Specific Treatment: No specific antidote; supportive care and observation are sufficient.

Monitor: Check liver function and hormone levels (e.g., progesterone) for 24–48 hours.

Patient Education: Advise against taking multiple doses and to store safely.

Additional Notes

• Overdose risk is low with proper use; systemic absorption from IUD is minimal.
• Report persistent symptoms (e.g., severe abdominal pain, irregular bleeding) promptly.

Drug Interactions with Levonorgestrel

This active ingredient may interact with:

• CYP3A4 Inducers: Reduces efficacy (e.g., rifampin, St. John’s Wort); use backup contraception.
• Anticonvulsants: Decreases levels (e.g., phenytoin); monitor.
• Antiretrovirals: Alters metabolism (e.g., ritonavir); adjust dose.
• Hormonal Therapies: Potentiates effects (e.g., estrogen); monitor.
• Antibiotics: Minor effect (e.g., ampicillin); use caution.

Action: Provide your healthcare provider with a complete list of medications.

Patient Education or Lifestyle

Pharmacokinetics of Levonorgestrel

Absorption: Oral, peak at 1–2 hours; IUD provides sustained release (10–20 µg/day initially).

Distribution: Volume of distribution ~1.8 L/kg; 50% protein-bound.

Metabolism: Hepatic via CYP3A4 to inactive metabolites.

Excretion: Primarily renal (as glucuronides); half-life 24–36 hours.

Half-Life: 24–36 hours, with prolonged effect from IUD.

Pharmacodynamics of Levonorgestrel

This drug exerts its effects by:

• Inhibiting ovulation by suppressing LH surge via hypothalamic-pituitary axis.
• Thickening cervical mucus to block sperm penetration.
• Altering endometrial lining to prevent implantation.
• Exhibiting dose-dependent risks of irregular bleeding and hormonal side effects.

Storage

• Temperature: Store at 20–25°C (68–77°F); protect from light and moisture.
• Protection: Keep in original packaging, away from heat.
• Safety: Store in a secure location out of reach of children and pets.
• Disposal: Dispose of unused tablets or IUD packaging per local regulations or consult a pharmacist.

Frequently Asked Questions (FAQs)

Q: What does Levonorgestrel treat?
A: This medication prevents pregnancy and manages heavy periods.

Q: Can this active ingredient cause irregular bleeding?
A: Yes, irregular bleeding is common; consult if persistent.

Q: Is Levonorgestrel safe for adolescents?
A: Yes, with supervision.

Q: How is this drug taken?
A: Orally or via IUD, as directed.

Q: How long is Levonorgestrel effective?
A: Up to 8 years with IUD, or 120 hours for emergency use.

Q: Can I use Levonorgestrel if pregnant?
A: No, it’s contraindicated; consult a doctor.

Regulatory Information

This medication is approved by:

U.S. Food and Drug Administration (FDA): Approved in 1999 (Plan B) for emergency contraception.

European Medicines Agency (EMA): Approved for contraception and menorrhagia.

Other Agencies: Approved globally for reproductive health; consult local guidelines.

References

1. U.S. Food and Drug Administration (FDA). (2023). Plan B One-Step (Levonorgestrel) Prescribing Information.
   • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
2. European Medicines Agency (EMA). (2023). Levonorgestrel Summary of Product Characteristics.
   • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
3. National Institutes of Health (NIH). (2023). Levonorgestrel: MedlinePlus Drug Information.
   • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
4. World Health Organization (WHO). (2023). WHO Model List of Essential Medicines: Levonorgestrel.
   • WHO’s inclusion of Levonorgestrel for emergency contraception.
5. Contraception Journal. (2022). Levonorgestrel IUD Efficacy.
   • Peer-reviewed article on Levonorgestrel efficacy (note: access may require a subscription).