Emergency contraception is a safe way to reduce the chance of pregnancy after sex when your regular birth control was not used, failed, or something unexpected happened. It is not meant to replace regular birth control, but it can be an important backup option.
1. What Emergency Contraception Is (and Is Not)
Emergency contraception (EC) is any method used after unprotected sex to lower the chance of getting pregnant. It works best when used as soon as possible, usually within 5 days of sex.
EC is:
- A way to help prevent pregnancy after unprotected sex or birth control failure.
- Safe for most teens and adults, including people who have never been pregnant.
- A one-time backup method, not an everyday birth control plan.
EC is not:
- An abortion pill – it does not end a pregnancy that has already started.
- A protection against sexually transmitted infections (STIs).
- A guarantee that pregnancy will not happen, though it greatly lowers the risk.
2. When Someone Might Need Emergency Contraception
Someone might consider EC after any situation where pregnancy could be possible, such as:
- Sex without any birth control.
- A condom that broke, slipped off, or was used incorrectly.
- Missing birth control pills, patch, or ring for more than the recommended time.
- Forgetting to get a birth control shot on time.
- Sex after a sexual assault, if pregnancy is a concern.
The sooner EC is used, the more effective it will be, especially in the first 24–72 hours.
3. Types of Emergency Contraception
There are two main categories of emergency contraception:
- Pills taken after sex (often called the “morning-after pill”).
- Copper IUD placed in the uterus by a health care provider.
| Method | What It Is | Time Limit After Sex | Typical Effectiveness |
|---|---|---|---|
| Levonorgestrel pill (LNG) | Over-the-counter hormone pill to delay ovulation | Up to 72 hours; can be used up to 120 hours but less effective over time | Reduces pregnancy risk by about 75–89% when taken promptly |
| Ulipristal acetate pill (UPA) | Prescription pill that blocks or delays ovulation | Up to 120 hours (5 days) after sex | More effective than levonorgestrel, especially 3–5 days after sex |
| Copper IUD | Small device placed in uterus; uses copper to prevent pregnancy | Up to 120 hours after sex | More than 99% effective; most effective EC option |
4. How Each Method Works
4.1 Levonorgestrel Emergency Pills
Levonorgestrel pills are often sold as single-dose tablets at pharmacies. They contain a form of the hormone progestin.
They work mainly by:
- Delaying or stopping ovulation (release of an egg from the ovary).
- Possibly changing cervical mucus or the lining of the uterus, making it harder for sperm to meet an egg.
If ovulation has already happened, levonorgestrel may not work as well. Effectiveness also drops the longer someone waits after sex.
4.2 Ulipristal Acetate Emergency Pills
Ulipristal acetate is a prescription-only emergency pill that can be taken up to 5 days after unprotected sex.
It works by:
- Blocking the hormone progesterone so that ovulation is delayed or prevented even when the body is close to releasing an egg.
- Remaining effective later in the 5-day window compared with levonorgestrel.
Studies show ulipristal is more effective than levonorgestrel, especially between 72 and 120 hours after sex.
4.3 Copper IUD as Emergency Contraception
The copper IUD is a small, T-shaped device placed into the uterus by a trained clinician. When used as EC, it must be inserted within 5 days of unprotected sex.
It prevents pregnancy by:
- Releasing copper ions, which are toxic to sperm and make it difficult for them to move and fertilize an egg.
- Possibly preventing implantation if fertilization were to occur.
When used correctly within the time limit, copper IUDs are more than 99% effective in preventing pregnancy as emergency contraception.
5. How Effective Is Emergency Contraception?
Effectiveness depends on the method used and how quickly it is taken after sex:
- Levonorgestrel pills
- Can prevent most pregnancies if taken within 72 hours, with estimates around 75–89% risk reduction.
- Effectiveness decreases as more time passes and may be lower in people with higher body weight.
- Ulipristal acetate pills
- Have pregnancy rates around 0.9–2.1% in studies, making them more effective than levonorgestrel pills.
- Maintain better effectiveness from day 3 to day 5 after sex.
- Copper IUD
- Has a pregnancy rate below 1%, often quoted under 0.1% in reviews, making it the most effective EC method.
- Also provides long-term birth control for up to 10–12 years, depending on the device.
6. Safety, Side Effects, and What to Expect
6.1 Common Side Effects of EC Pills
Most side effects are mild and go away on their own within a few days. Possible effects include:
- Nausea or upset stomach.
- Feeling tired or dizzy.
- Headache.
- Breast tenderness.
- Changes in the next period (earlier, later, or heavier than usual).
Some people may have light spotting or bleeding before their next full period. If vomiting happens within a few hours of taking the pill, a health care provider may recommend taking another dose.
6.2 Safety of EC Pills
- Emergency pills are considered safe for most people, including teens.
- They do not affect long-term fertility or the ability to get pregnant in the future.
- They do not harm an existing pregnancy if taken by someone who is already pregnant.
6.3 Side Effects and Risks of the Copper IUD
Possible short-term effects after IUD insertion include:
- Cramping during and shortly after insertion.
- Spotting or irregular bleeding.
- Heavier periods and more cramping in the first months.
Serious complications like infection or uterine perforation are rare when the IUD is placed by an experienced provider.
7. Access: How Teens Can Get Emergency Contraception
7.1 Getting EC Pills
Availability can vary by country, region, and local laws, but generally:
- Levonorgestrel pills are often sold without a prescription at pharmacies, drugstores, and some clinics.
- Ulipristal acetate usually requires a prescription from a doctor, nurse practitioner, or clinic.
- Some clinics and health centers may provide EC at low or no cost for teens.
7.2 Getting a Copper IUD for EC
To use a copper IUD as emergency contraception, someone must:
- See a clinician (such as a doctor or nurse practitioner) who can insert IUDs.
- Schedule the insertion within 5 days of unprotected sex.
- Discuss ongoing birth control options once the IUD is in place.
Because an appointment and procedure are required, planning and quick contact with a clinic are important for this option.
8. Myths and Facts About Emergency Contraception
- Myth: Emergency contraception is the same as an abortion pill.
Fact: EC works by preventing or delaying ovulation and fertilization. It does not end an existing pregnancy. - Myth: Using EC once can make you infertile.
Fact: Research shows that EC does not harm future fertility or make it harder to get pregnant later. - Myth: EC pills only work if taken the morning after sex.
Fact: Many EC pills can be used up to 3–5 days after sex, though they are most effective the sooner they are taken. - Myth: EC protects against STIs.
Fact: EC does not prevent infections. Condoms and regular STI testing are still important for sexual health.
9. Planning Ahead and Next Steps
9.1 After Using Emergency Contraception
After taking EC or having a copper IUD inserted, it is helpful to:
- Monitor your next period. If it is more than a week later than expected, consider taking a pregnancy test.
- Use condoms or another backup method until starting or restarting regular birth control.
- Talk with a health care provider about long-term birth control options.
9.2 Choosing Ongoing Birth Control
Emergency contraception is not meant to be a regular method of birth control. More reliable ongoing options include:
- Long-acting reversible contraception (LARC) like hormonal IUDs or implants.
- Birth control pills, patch, ring, or shot.
- Condoms, which also protect against many STIs.
A clinician, school-based health center, or sexual health clinic can help explain choices and find something that fits your health needs and lifestyle.
10. Frequently Asked Questions (FAQs)
Q1: How soon should I take emergency contraception after sex?
Emergency contraception works best when used as early as possible. Levonorgestrel pills are most effective within 72 hours, ulipristal acetate and copper IUDs can be used up to 120 hours (5 days) with good effectiveness.
Q2: Can I use emergency contraception more than once?
Yes, EC pills can be used again if needed, and there is no set maximum number of times in a lifetime. However, relying on EC repeatedly is less effective than using a regular birth control method, so it is better to talk with a provider about ongoing contraception.
Q3: Will emergency contraception harm a baby if I’m already pregnant?
Current evidence shows that EC pills do not harm an existing pregnancy and will not cause birth defects. They simply will not work if pregnancy has already started.
Q4: Do I need my parents’ permission to get emergency contraception?
In many places, teens can get EC pills without parental consent, especially over-the-counter levonorgestrel pills. Laws differ by country and region, so it is important to check local rules or speak with a health clinic for guidance.
Q5: What if my BMI or weight is higher?
Some research suggests levonorgestrel pills may be less effective in people with higher body weight or BMI. Ulipristal acetate or a copper IUD may be better options in this situation, so talking with a clinician as soon as possible is important.
Q6: Do I still need condoms if I use other birth control?
Yes. Condoms help protect against many sexually transmitted infections, which hormonal methods and IUDs do not prevent. For both pregnancy and STI protection, many experts recommend using condoms along with a reliable birth control method.
References
- Emergency contraception — World Health Organization. 2021-02-25. https://www.who.int/news-room/fact-sheets/detail/emergency-contraception
- Emergency Contraception — Centers for Disease Control and Prevention (CDC). 2024-01-10. https://www.cdc.gov/contraception/hcp/usspr/emergency-contraception.html
- Emergency contraception review: evidence-based recommendations for clinicians — Glasier AF et al., International Journal of Women’s Health. 2014-10-07. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4216625/
- Emergency Contraception: Safety and Effectiveness — American Family Physician (AAFP). 2020-06-01. https://www.aafp.org/pubs/afp/issues/2020/0601/p651.html
- The facts about emergency contraception — Massachusetts Department of Public Health (Mass.gov). 2023-05-18. https://www.mass.gov/info-details/the-facts-about-emergency-contraception
- Morning After Pill: Emergency Contraception & Side Effects — Cleveland Clinic. 2022-06-30. https://my.clevelandclinic.org/health/treatments/23386-morning-after-pill
