Levonorgestrel

Emergency Contraception

Levonorgestrel is used as emergency contraception to prevent pregnancy after unprotected sexual intercourse or when a primary birth control method fails. It is most effective when taken as soon as possible after the event and is intended for backup use rather than as a regular form of contraception.

Long-Term Pregnancy Prevention

This medication is used for ongoing pregnancy prevention in several different forms:

• Intrauterine System: A small device placed in the uterus by a healthcare provider that releases the hormone over several years to provide continuous contraception.
• Oral Contraceptives: It is often used in combination with estrogen in daily birth control pills to prevent ovulation.

Heavy Menstrual Bleeding

The intrauterine form of levonorgestrel is also used to treat heavy menstrual bleeding. This application is typically for individuals who also desire a long-term, reversible method of birth control.

Mechanism of Action

Levonorgestrel belongs to a class of medications known as progestins. It works in several ways to prevent pregnancy, depending on the specific form of the medication and when it is used:

• Preventing Ovulation: The primary way levonorgestrel works is by preventing or delaying the release of an egg from the ovary. If an egg is not released, fertilization cannot occur.
• Thickening Cervical Mucus: It increases the thickness of the mucus at the cervix (the opening of the uterus). This creates a physical barrier that makes it difficult for sperm to travel into the uterus to reach an egg.
• Altering the Uterine Lining: Levonorgestrel may change the lining of the uterus (the endometrium). This change can make the environment less favorable for a fertilized egg to attach to the uterine wall.

It is important to note that levonorgestrel is intended to prevent pregnancy before it begins. It is not effective if a person is already pregnant and it will not terminate an existing pregnancy.

Common Side Effects

The most frequently reported side effects of levonorgestrel are generally mild and temporary. They may include:

• Nausea and vomiting
• Stomach or abdominal pain
• Tiredness or fatigue
• Headache
• Dizziness
• Breast tenderness

Menstrual Cycle Changes

Levonorgestrel can alter your next menstrual period. Common changes include:

• Spotting or bleeding between periods
• Heavier or lighter menstrual flow
• A period that arrives earlier or later than expected

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Severe pain in the lower abdomen or side, which may be a sign of a pregnancy outside the uterus (ectopic pregnancy)
• Signs of a severe allergic reaction, such as hives, rash, or swelling of the face, lips, or throat
• Difficulty breathing or swallowing

Pregnancy and Ectopic Risk

Levonorgestrel will not terminate an existing pregnancy and is not effective if a person is already pregnant. If pregnancy occurs after use, or if there is persistent or severe lower abdominal pain, medical evaluation is necessary to rule out an ectopic pregnancy, which is a pregnancy located outside the uterus.

Contraindications

• Hypersensitivity to levonorgestrel or any ingredients in the product.
• Known or suspected pregnancy (for certain formulations).
• Undiagnosed abnormal vaginal bleeding.
• Current or history of breast cancer or other progestin-sensitive cancers.
• Active liver disease or liver tumors.

General Precautions

This medication does not provide protection against HIV/AIDS or other sexually transmitted infections (STIs). When used as emergency contraception, it is not intended for routine use and should not replace regular contraceptive methods.

For intrauterine devices (IUDs) containing levonorgestrel, risks include pelvic inflammatory disease (PID), uterine perforation, and device expulsion. Individuals using long-term levonorgestrel implants or IUDs should be monitored for changes in menstrual bleeding patterns and other potential complications.

Pregnancy

Levonorgestrel is not intended for use in individuals who are already pregnant. If taken as emergency contraception, it will not terminate an existing pregnancy. Research indicates that accidental use during early pregnancy does not appear to cause birth defects or harm the developing fetus. However, if pregnancy occurs while using a levonorgestrel-releasing intrauterine system (IUD), there is an increased risk of ectopic pregnancy, which is a medical emergency. If you suspect you are pregnant while using any form of this medication, you should contact a healthcare provider immediately.

Breastfeeding

Levonorgestrel is excreted into breast milk. In general, the use of progestin-only medications is not thought to significantly impact the volume or quality of breast milk or the health and development of the nursing infant. Some healthcare providers may suggest waiting until six weeks postpartum to begin certain hormonal contraceptives to ensure breastfeeding is well-established. You should discuss the benefits and potential risks with a healthcare professional to determine the best timing for your situation.

Available Forms

Levonorgestrel is manufactured in various forms to provide both short-term and long-term contraception:

• Oral Tablets: These are typically used for emergency contraception and are taken by mouth.
• Intrauterine Systems: This is a small device that a healthcare professional places inside the uterus to provide continuous hormone release for long-term pregnancy prevention.
• Subdermal Implants: These are flexible rods placed under the skin of the upper arm by a medical provider.

Levonorgestrel is also used as a component in combination oral contraceptive pills alongside other hormones.

FDA Approval and Indications

Levonorgestrel is approved by the FDA in multiple forms for reproductive health. The 1.5 mg oral tablet is approved for emergency contraception to be taken within 72 hours of unprotected sex or contraceptive failure. In 2013, the FDA transitioned this specific dosage to over-the-counter status for all ages without a prescription.

The FDA has also approved levonorgestrel-releasing intrauterine systems (IUDs) for long-term contraception. Depending on the specific device, these are approved for use ranging from three to eight years. One intrauterine system is also indicated for the treatment of heavy menstrual bleeding in patients who choose intrauterine contraception.

Labeling and Safety Updates

In December 2022, the FDA updated the labeling for levonorgestrel emergency contraception to clarify its mechanism of action. The revised labeling states that the drug works by preventing or delaying ovulation and does not affect the implantation of a fertilized egg. The FDA confirmed that these products are not abortifacients and will not terminate an existing pregnancy.

Regulatory Requirements

Levonorgestrel products do not currently require a Risk Evaluation and Mitigation Strategy (REMS). While combination oral contraceptives containing levonorgestrel and estrogen carry boxed warnings regarding the risks of cigarette smoking and cardiovascular events, progestin-only levonorgestrel products generally do not include these specific boxed warnings.

How Plan B Works

Plan B is a progestin-only emergency contraceptive pill containing levonorgestrel. It is intended to prevent pregnancy after unprotected sexual intercourse or when a primary method of birth control has failed. It works by stopping the release of an egg from the ovary. It may also prevent fertilization of an egg or prevent a fertilized egg from attaching to the uterus. It is not an abortion pill and will not work if you are already pregnant.

Timing and Effectiveness

For the best results, Plan B should be taken as soon as possible, preferably within 72 hours (3 days) after unprotected sex. While it may still be used up to 120 hours (5 days) later, its effectiveness decreases significantly over time.

Common Side Effects

• Nausea and vomiting
• Lower abdominal pain
• Fatigue or tiredness
• Headache
• Dizziness
• Breast tenderness
• Changes in menstrual bleeding, such as spotting or a heavier or lighter next period

If you vomit within two hours of taking the medication, contact a healthcare professional to determine if you need to take another dose.

Important Considerations

Plan B does not provide long-term protection against pregnancy and should not be used as a regular form of birth control. It also does not protect against HIV infection or other sexually transmitted diseases. If your period is more than one week late after taking Plan B, you should take a pregnancy test to confirm you are not pregnant.