Plan B contains levonorgestrel as its active component. Levonorgestrel is a synthetic progestogen used globally as an emergency contraceptive. In Hong Kong, Plan B is classified as a prescription-only medication and is regulated by the Hong Kong Department of Health. The product is supplied as a single oral pill with a strength of 1.5 mg.
Levonorgestrel mimics the hormone progesterone, which regulates the menstrual cycle and prepares the uterine lining for implantation. When taken after unprotected intercourse, the drug can:
These actions are most effective when levonorgestrel is taken as early as possible after intercourse, ideally within 72 hours. The drug does not terminate an already established pregnancy.
Plan B is approved in Hong Kong for emergency contraception. Specifically, it is indicated to:
It is not intended for routine contraception and should not replace regular birth-control methods.
There are no widely accepted off-label uses for levonorgestrel in the context of emergency contraception that are supported by robust clinical guidelines. Consequently, this section is omitted.
If any of the above conditions apply, a healthcare professional should evaluate suitability before use.
These effects are generally short-lived and do not require medical intervention unless they persist.
Plan B carries a black-box warning in many jurisdictions for the rare risk of ectopic pregnancy if fertilization has already occurred.
No interaction data specific to Plan B beyond the class effects of levonorgestrel have been identified; patients should disclose all concurrent medications, supplements, and herbal products.
Routine laboratory monitoring is not required after a single dose of levonorgestrel. However, patients should:
If special storage instructions are printed on the package (e.g., “store below 25 °C”), follow those directives.
This article provides educational information about Plan B and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
Plan B is designed for single-use, post-coital emergency contraception and does not provide continuous protection. Regular contraceptive methods (e.g., oral pills, IUDs) are recommended for ongoing pregnancy prevention.
All levonorgestrel emergency pills contain the same active dose (1.5 mg) and share identical mechanisms. Brand-specific differences are limited to packaging, imprint codes, and manufacturer.
Yes, but effectiveness declines with time. While the drug remains more than 50 % effective up to 72 hours, earlier administration yields higher success rates.
Levonorgestrel passes into breast milk in small amounts and is not known to cause harm to a nursing infant. Short-term use for emergency contraception is generally considered safe, but discuss any concerns with a healthcare professional.
Plan B may cause the next period to arrive earlier or later than expected, and the flow may be lighter or heavier. These changes are temporary and typically resolve by the following cycle.
If vomiting occurs within 2 hours of ingestion, contact a healthcare provider. A repeat dose may be recommended to ensure adequate drug absorption.
Yes. Anticonvulsants (e.g., carbamazepine), antibiotics like rifampin, and herbal remedies such as St. John’s wort can lower levonorgestrel levels, potentially reducing effectiveness. Discuss all current medications with a pharmacist or prescriber.
Plan B is a prescription medication in many countries, including Hong Kong. Carry the original packaging, a copy of the prescription, and a doctor’s note if traveling to jurisdictions that may require documentation for hormonal products.
Some studies suggest reduced efficacy in individuals with higher body mass index (BMI > 30 kg/m²). While levonorgestrel remains an option, an alternative emergency contraceptive containing ulipristal acetate may be recommended for higher-BMI patients.
Do not flush tablets down the toilet. Follow local medication-take-back programs or return the product to a pharmacy for proper disposal.
