What is the recommended emergency contraception after unprotected sex, specifically using Plan B (levonorgestrel)?

Emergency Contraception with Plan B (Levonorgestrel)

Plan B (levonorgestrel 1.5 mg) should be taken as soon as possible within 72 hours after unprotected sex, as effectiveness decreases significantly with each passing day. 1, 2, 3

Recommended Emergency Contraception Options

Emergency contraception options in the United States include:

1. Levonorgestrel (Plan B):

   • Single 1.5 mg dose OR two 0.75 mg doses taken 12 hours apart 1, 3
   • Most effective when taken within 72 hours (3 days) of unprotected sex 1, 2, 3
   • Reduces pregnancy risk by approximately 75-88% when used correctly 2
   • Effectiveness decreases with time - take as soon as possible 3, 4

2. Ulipristal acetate (Ella):

   • Single 30 mg dose 1
   • Can be used up to 5 days (120 hours) after unprotected sex 1
   • More effective than levonorgestrel between 3-5 days after unprotected sex 1, 5
   • Better option for overweight or obese women 1, 2

3. Copper IUD:

   • Most effective emergency contraception method overall 1, 2
   • Can be inserted up to 5 days after unprotected sex 1, 2
   • Can be continued as regular contraception 1

Effectiveness of Plan B (Levonorgestrel)

• Effectiveness decreases with time:

  • When taken within 24 hours: highest effectiveness (up to 91%) 2, 4
  • When taken within 72 hours: approximately 75-88% effective 2, 3
  • When taken between 72-120 hours: significantly reduced effectiveness 1, 4
  • Taking on day 5 (96-120 hours) increases pregnancy risk five-fold compared to taking within 24 hours 4

• About 7 out of 8 women who would have become pregnant will not become pregnant when using Plan B correctly 3

Important Clinical Considerations

1. Timing is critical:

   • Take Plan B as soon as possible after unprotected sex 1, 3
   • Each 24-hour delay reduces effectiveness 4

2. Administration:

   • No pelvic examination required 6
   • Can be taken as a single 1.5 mg dose or two 0.75 mg doses 12 hours apart 1, 7
   • If vomiting occurs within 2 hours of taking Plan B, contact healthcare provider about repeating the dose 3

3. Follow-up:

   • Expect menstruation within 1 week of expected time 3
   • Pregnancy test recommended if period is more than 1 week late 3
   • Evaluate for pregnancy if menses have not begun within 21 days following treatment 6

4. Post-Plan B contraception:

   • Regular contraceptive methods can be started immediately after using Plan B 1
   • Abstain from sex or use barrier contraception for 7 days after Plan B use 1

5. Common side effects:

   • Changes in menstrual cycle (heavier/lighter or early/late period)
   • Nausea, abdominal pain, tiredness, headache, dizziness, breast tenderness 3

Important Caveats

• Plan B is not for regular contraception - it's less effective than regular birth control methods 2, 3

• Plan B will not affect an existing pregnancy and is not an abortion pill 2, 3

• Plan B does not protect against HIV or other sexually transmitted infections 2

• Advance provision of Plan B may be provided so it's available when needed 1

• Plan B may be less effective in women who are overweight or obese 1, 2

• Plan B should not be used if:

  • Already pregnant (it won't work) 3
  • Allergic to levonorgestrel or other ingredients 3

• Certain medications may reduce effectiveness:

  • Efavirenz (HIV medication)
  • Rifampin (tuberculosis treatment)
  • Seizure medications 3

In these cases, consider alternative emergency contraception options like copper IUD or consult with a healthcare provider.