Plan B Side Effects at 3 Days Post-Intercourse
If a patient took Plan B (levonorgestrel) 3 days after intercourse, she should expect common side effects including menstrual changes, nausea, lower abdominal pain, fatigue, headache, dizziness, and breast tenderness, with these symptoms being generally mild to moderate and self-limited. 1
Expected Side Effects
The FDA-approved labeling for levonorgestrel identifies the following side effects that patients may experience after taking Plan B 1:
- Menstrual changes (most common): Period may be heavier, lighter, earlier, or later than expected 1
- Nausea 1
- Lower abdominal pain 1
- Fatigue/tiredness 1
- Headache 1, 2
- Dizziness 1
- Breast tenderness 1, 2
Timeline and What to Expect
The patient should expect her next period at the expected time or within one week of the expected time. 1 If the period is delayed by more than one week beyond the expected date, pregnancy testing is indicated as the emergency contraception may have failed 1.
Research indicates that levonorgestrel causes less nausea and vomiting compared to combined estrogen-progestin emergency contraceptive regimens, making it better tolerated 3. The side effects are generally mild to moderate in severity 4, 2.
Critical Warning Signs
If the patient develops severe abdominal pain, she requires immediate medical attention to rule out ectopic pregnancy. 1 This is a critical complication that must not be missed if the emergency contraception fails.
Important Counseling Points
- Vomiting within 2 hours of taking the medication: If this occurred, the patient should contact a healthcare provider to determine if a repeat dose is needed 1
- Efficacy considerations: Since the patient took Plan B at 3 days (72 hours) post-intercourse, she is at the outer limit of optimal effectiveness. The CDC guidelines note that pregnancy rates are slightly higher when emergency contraceptive pills are taken after 3 days, with efficacy decreasing at 4-5 days 3
- Follow-up: A pregnancy test is warranted if withdrawal bleeding does not occur within 3 weeks 3
Common Pitfall to Avoid
Do not reassure the patient that Plan B is 100% effective. The medication prevents approximately 7 out of 8 expected pregnancies when taken as directed 1, meaning there is still a pregnancy risk that necessitates follow-up if menses is delayed.