Emergency contraception using levonorgestrel 1.5 mg (Plan B) is most effective when taken within:

• A 72 hours of unprotected intercourse ✓
• B 12 hours of unprotected intercourse
• C 120 hours of unprotected intercourse
• D 96 hours of unprotected intercourse

Explanation

Levonorgestrel emergency contraception (EC) is licensed for use up to 72 hours after unprotected intercourse, with efficacy declining with time: 95% if taken within 24 hours, 85% within 25-48 hours, 58% within 49-72 hours. It is NOT effective after 72 hours. The Cu-IUD is effective as EC up to 120 hours (5 days) after unprotected sex and provides ongoing contraception. Ulipristal acetate (ella) is also effective up to 120 hours. The mechanism of LNG-EC is primarily inhibition/delay of ovulation — NOT abortifacient (does not disrupt established implantation).

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.