What to do after unprotected sex to prevent pregnancy?

Emergency Contraception After Unprotected Sex

Take emergency contraception as soon as possible, ideally within 120 hours (5 days) of unprotected intercourse, with the copper IUD being the most effective option and ulipristal acetate (30 mg) being the best oral choice. 1, 2

Immediate Action Required

Act quickly—effectiveness decreases with time. Emergency contraception should be taken as soon as possible after unprotected intercourse, though options remain available up to 5 days later. 1, 3

Best Emergency Contraception Options (In Order of Effectiveness)

1. Copper IUD (Most Effective)

• The copper IUD is the single most effective emergency contraception method, with the highest efficacy rate. 1, 2
• Can be inserted within 5 days of unprotected intercourse (or up to 5 days after ovulation if that day can be estimated). 1
• Provides the added benefit of ongoing long-term contraception after insertion. 2, 4
• No hormonal interactions with existing contraceptive methods. 2

2. Ulipristal Acetate (UPA) - 30 mg Single Dose

• UPA is the most effective oral emergency contraception option, particularly when taken 3-5 days after unprotected intercourse. 1, 2
• Maintains consistent effectiveness throughout the full 120-hour (5-day) window. 1, 2, 3
• More effective than levonorgestrel in women who are overweight or obese. 2
• Available by prescription only. 3, 4
• Take one 30 mg tablet orally as soon as possible within 120 hours of unprotected intercourse. 3

3. Levonorgestrel - 1.5 mg Single Dose or Split Dose

• Take 1.5 mg as a single dose OR 0.75 mg followed by another 0.75 mg 12 hours later. 1, 5
• Most effective within 72 hours (3 days) of unprotected intercourse. 1, 4
• Effectiveness significantly decreases after 72 hours, making it less reliable at 4-5 days. 2
• Available over-the-counter without prescription. 5
• May be less effective in obese women compared to UPA. 1

4. Combined Estrogen-Progestin Pills (Yuzpe Method) - Least Recommended

• Less effective than UPA or levonorgestrel. 1
• Associated with more frequent side effects, particularly nausea and vomiting. 1, 6
• Generally not recommended given better alternatives. 1

Critical Timing Considerations After Taking Emergency Contraception

After Levonorgestrel:

• Resume or start regular hormonal contraception immediately. 2
• Use barrier contraception (condoms) or abstain for 7 consecutive days after restarting hormonal contraception. 2

After Ulipristal Acetate (UPA):

• Do NOT start hormonal contraception for at least 5 days after taking UPA, as progestin-containing contraceptives may impair UPA's ability to delay ovulation. 2, 3
• After 5 days, any contraceptive method can be started. 2, 3
• Use barrier contraception or abstain for 14 consecutive days (or until next menstrual period) after UPA use. 2, 3

After Copper IUD:

• No waiting period required—provides immediate ongoing contraception. 2

Important Warnings and Follow-Up

If Vomiting Occurs:

• If vomiting occurs within 3 hours of taking the emergency contraception pill, consider repeating the dose. 1, 3

Pregnancy Testing:

• If your period is more than 1 week late, take a pregnancy test and contact your healthcare provider. 3, 7
• Emergency contraception may cause your next period to come earlier or later than expected. 3

Ectopic Pregnancy Warning:

• If you develop severe lower abdominal pain 3-5 weeks after taking emergency contraception, seek immediate medical attention to rule out ectopic pregnancy. 3

Subsequent Intercourse:

• Emergency contraception does NOT protect against future acts of unprotected intercourse. 2, 3
• Use barrier contraception (condoms) for any subsequent intercourse until your next menstrual period and regular contraception is established. 2, 3

Common Pitfalls to Avoid

• Do not delay taking emergency contraception—effectiveness decreases significantly with time, especially for levonorgestrel beyond 72 hours. 1, 2, 7
• Do not start hormonal contraception immediately after UPA—wait at least 5 days to avoid reducing UPA's effectiveness. 2, 3
• Do not assume emergency contraception is 100% effective—pregnancy can still occur, requiring follow-up if menses is delayed. 3, 7
• Do not use emergency contraception as routine contraception—it is less effective than regular contraceptive methods. 3, 4, 6
• Emergency contraception does not protect against sexually transmitted infections. 1, 3