Plan B and Fertility: Understanding the Safety of Emergency Contraception

Alan Lucks | MD

Medically reviewed by Alan Lucks | MD, Alan Lucks MDPC Private Practice - New York on February 20th, 2026.

Key Takeaways

  • Plan B does not cause long-term fertility issues

  • Emergency contraception temporarily alters hormone levels

  • Multiple uses do not impact future pregnancy potential

  • Consulting a healthcare provider is recommended for ongoing contraception needs

Emergency contraceptive pills like Plan B have become an important option for women seeking to prevent unintended pregnancy. Many women worry about the potential long-term impacts of using emergency contraception multiple times. Understanding how soon after unprotected sex you can take Plan B and its effects is crucial for making informed reproductive health decisions.

Plan B contains levonorgestrel, a synthetic hormone that prevents pregnancy by delaying or stopping ovulation. When taken within 72 hours of unprotected intercourse, it can significantly reduce the risk of pregnancy. Unlike some misconceptions, research on birth control during pregnancy and emergency contraception shows no evidence of long-term fertility damage.

Understanding Plan B's Mechanism

When taken, Plan B works by:

  • Preventing or delaying ovulation

  • Thickening cervical mucus to block sperm

  • Potentially preventing egg implantation

Fertility and Repeated Use

Medical research consistently demonstrates that frequent use of Plan B does not impact a woman's ability to conceive. Reliable online gynecologists confirm that the medication provides a temporary hormonal intervention without causing permanent reproductive changes.

Potential Side Effects and Considerations

Side Effect

Duration

Typical Experience

Irregular Bleeding

1-2 Months

Temporary cycle changes

Nausea

24-48 Hours

Mild to moderate

Breast Tenderness

1-2 Weeks

Variable intensity

Menstrual Cycle Shift

1-2 Months

Timing may vary

When to Seek Professional Guidance

While Plan B is safe, frequent use suggests a need to explore more consistent contraception methods. Gynecological care providers recommend discussing long-term birth control options that offer more reliable pregnancy prevention.

Frequently Asked Questions

No, medical research shows no long-term fertility risks with repeated use.

Most effective when taken within 72 hours of unprotected intercourse.

No, it's designed for emergency use and is less effective than consistent contraception.

Generally available over-the-counter for individuals of all ages.

No, it only prevents pregnancy and does not protect against sexually transmitted infections.

The Bottom Line

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