Emergency contraception from Nurx costs as little as $0 with insurance or $45 per pill without insurance.
If you’ve taken Plan B® One-Step emergency contraception (Levonorgestrel 1.5 mg), it’s natural to wonder whether it was effective. The only way to know for sure is to take a pregnancy test if your period is more than a week late. Signs that Plan B® may not have worked include a missed period, a positive pregnancy test, or pregnancy symptoms such as breast tenderness, nausea, or fatigue appearing several weeks after taking the pill.
What are the signs that Plan B® didn’t work?
The most reliable sign that Levonorgestrel (generic Plan B®) may not have worked is a missed period that’s more than 7 days late. You may also notice signs of early pregnancy, which usually appear 2–8 weeks after unprotected sex, such as:
- Breast tenderness or swelling
- Nausea or morning sickness
- Fatigue or unusual tiredness
- Increased urination
- Food cravings or aversions
- Light spotting or mild cramping
If your period is late, the best way to know for sure is to take a pregnancy test.
How rare is it for Plan B® not to work?
Levonorgestrel (generic Plan B®) is highly effective, but not perfect. When taken within 72 hours of unprotected sex, it reduces the chance of pregnancy by about 87% overall. The sooner you take it, the better it works:
- Within 24 hours: about 95% effective
- Within 72 hours: about 87% effective
That means about 1 in 8 people may still become pregnant even after taking it, depending on timing and other factors.
What does discharge look like after Plan B®?
Changes in discharge after Plan B® are usually related to hormonal shifts. You may notice discharge that is:
- Thicker, white, or creamy
- Slightly different in texture or amount
This is typically normal and not a sign of pregnancy. If your discharge is clear, stretchy, and egg-white-like, it may indicate ovulation, which could mean Plan B® was less effective at preventing egg release.
What cancels out a Plan B® pill?
Several factors can lower how well Plan B® works:
- Taking it more than 72 hours after unprotected sex, though it may still be effective for up to five days
- Vomiting within 2 hours of taking the pill (before it’s absorbed)
- Certain medications or supplements (like some HIV medicines, barbiturates, or St. John’s Wort)
- Having unprotected sex again after taking emergency contraception
- Body weight over 165 pounds (effectiveness may be reduced)
- Already being pregnant when you take it (Plan B® won’t end an existing pregnancy)
What are some signs that Plan B® is working?
It’s not always obvious, but some people may notice mild side effects that suggest the medication is doing its job. These can include:
- Nausea or stomach upset within 24–48 hours
- Breast tenderness, headache, dizziness, cramping or spotting shortly after taking emergency contraception
- Changes in your next period (earlier, later, lighter, or heavier than usual)
These symptoms are usually temporary and should resolve on their own.
How to manage failed Plan B®
If you’re worried that Plan B® didn’t work:
- Wait at least 3 weeks after unprotected sex, then take a pregnancy test for accurate results.
- If your period is more than a week late, test sooner.
- Reach out to a healthcare provider if you’re unsure what’s normal for you.
At Nurx, our medical team can help you understand your emergency contraception options, answer questions about how Levonorgestrel (generic Plan B®) works, and support you in choosing ongoing birth control that fits your life.
The information provided is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon this content for medical advice. If you have any questions or concerns, please talk to a medical professional.
Services not offered in every state. Medications prescribed only if clinically appropriate, based on completion of the required consultation. Individual results may vary.
Ella® (Ulipristal Acetate tablet, 30mg), Rx only, is an emergency contraceptive used to prevent pregnancy up to five days (120 hours) after unprotected sex. Ella® may cause side effects, including headache, nausea, and stomach pain. If you would like to learn more about Ella®, please see the full prescription information here.
Levonorgestrel (generic Plan B®) tablet 1.5 mg, intended to reduce the chance of pregnancy after unprotected sex, may cause side effects, including dizziness, abdominal pain, diarrhea, headache, fatigue, irregular menstruation, breast tenderness, nausea or spotting. If you would like to learn more about Levonorgestrel tablet 1.5 mg, please see product information here.