What Is Plan B? Your Complete Guide to Emergency Contraception

Alan Lucks | MD

Medically reviewed by Alan Lucks | MD, Alan Lucks MDPC Private Practice - New York on January 24th, 2026.

Key Takeaways

  • Plan B is an over-the-counter emergency contraception pill

  • Most effective when taken within 72 hours of unprotected sex

  • Works by delaying ovulation, not terminating an existing pregnancy

  • Available without prescription for all ages and genders

Emergency contraception is an important reproductive health option for individuals seeking to prevent unintended pregnancy. Plan B, also known as the morning-after pill, offers a time-sensitive solution for those who have had unprotected sexual intercourse or experienced contraceptive failure.

Plan B is a levonorgestrel-based emergency contraceptive designed to help prevent pregnancy when taken shortly after unprotected sexual activity. Unlike abortion medication, this pill works by temporarily stopping the release of an egg from the ovary, making fertilization less likely. Refill a prescription through Doctronic if you need ongoing contraceptive support.

The medication is widely available and does not require a prescription, making it accessible to individuals of all ages and genders. When used correctly, Plan B can significantly reduce the chance of unintended pregnancy.

How Plan B Works

Plan B functions by preventing ovulation, which means it stops an egg from being released from the ovary. If no egg is available for fertilization, pregnancy cannot occur. The medication is most effective when taken as soon as possible after unprotected intercourse. Taking adapalene or other medications may not interfere with Plan B's effectiveness.

The pill contains a high dose of levonorgestrel, a synthetic hormone similar to progesterone. By mimicking natural hormonal processes, it temporarily disrupts the reproductive cycle and prevents fertilization. Effectiveness ranges from 75-89% when taken within the recommended timeframe.

Effectiveness and Timing

Timing is crucial when using Plan B. The pill is most effective when taken within 72 hours (3 days) of unprotected sex, with effectiveness declining the longer you wait. While the medication can be taken up to 120 hours (5 days) after intercourse, the chances of preventing pregnancy decrease significantly after the first 72 hours.

Timeframe

Effectiveness Rate

Within 24 hours

95%

24-72 hours

89%

72-120 hours

75%

Side Effects and Considerations

Most individuals experience minimal side effects when taking Plan B. Common temporary symptoms include:

  • Slight changes in menstrual cycle

  • Mild headaches

  • Temporary nausea

  • Potential breast tenderness

  • Possible fatigue

  • Dizziness

Avoid when you're taking Bactrim or other medications that might interact with emergency contraception. Consulting a healthcare professional can help you understand potential interactions.

Availability and Cost

Plan B and its generic equivalents are available over-the-counter at most pharmacies. Prices typically range from $11 to $50, depending on the brand. Some health insurance plans and clinics offer reduced or free access to emergency contraception.

Frequently Asked Questions

Is Plan B an abortion pill?

No, Plan B prevents pregnancy by delaying ovulation and is not designed to terminate an existing pregnancy.

Can anyone purchase Plan B?

Yes, it's available without prescription for all ages and genders.

How often can I use Plan B?

While safe, it's not recommended as a regular form of birth control. Consult a healthcare provider about consistent contraceptive methods.

Does weight affect Plan B's effectiveness?

Individuals weighing over 165 pounds may experience reduced effectiveness and should consult a healthcare provider.

Are there long-term side effects?

Current medical research indicates no significant long-term health risks from occasional Plan B use.

The Bottom Line

Emergency contraception provides an important option for reproductive health management. Taking baloxavir marboxil or other medications should not prevent you from accessing emergency contraception when needed.

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