If sperm entered your vagina and you’re not trying to get pregnant, the most important thing to know is that you have up to five days to act, but sooner is better. Emergency contraception can significantly reduce your chance of pregnancy, and several options are available depending on how quickly you can access them. Here’s what to do, step by step.
Don’t Try to Wash It Out
The urge to rinse or clean inside the vagina is understandable, but it doesn’t work. Sperm swim fast, and many reach the uterus before any washing could begin. Douching, using vinegar, vaginal cleansers, or any other home remedy will not prevent pregnancy. In fact, washing inside the vagina can actually push sperm further toward the uterus and increase the risk of pelvic infection. Urinating afterward also has no effect on pregnancy risk, since urine exits from a separate opening.
Emergency Contraception: Your Main Options
Four types of emergency contraception are available in the United States, and all can be used within five days of unprotected sex. The sooner you use any of them, the more effective they are.
Levonorgestrel Pills (Plan B and Generics)
This is the most widely available option. You can buy it over the counter at most pharmacies without a prescription or age restriction. It works best when taken within the first 24 hours but can be used up to five days after sex. Effectiveness drops noticeably with each passing day.
One important limitation: body weight affects how well this pill works. People with a BMI of 30 or higher experience failure rates about four times higher than those with a BMI under 25. Research from Oregon Health & Science University found that blood levels of the active ingredient were 50% lower in people with a BMI of 30 after taking a standard dose, meaning the pill may never reach the level needed to prevent ovulation. Doubling the dose does not solve this problem. If your BMI is 30 or above, one of the other options below will be more reliable.
Ulipristal Acetate (Ella)
This pill requires a prescription but maintains its effectiveness better over the full five-day window. Within the first three days, it performs similarly to levonorgestrel. Between days three and five, it’s notably more effective. If you can’t get to a pharmacy right away, or if you’re past the 72-hour mark, this is the better pill option. Some telehealth services can prescribe it quickly.
The Copper IUD
A copper IUD placed within five days of unprotected sex is the most effective form of emergency contraception available, preventing pregnancy more than 99% of the time. It requires a clinic visit for insertion, but it then doubles as long-term birth control for up to 10 years. If the day of ovulation can be estimated, a copper IUD can sometimes be placed even beyond five days after sex, as long as it’s inserted within five days of ovulation. This is the strongest option for anyone concerned about the pill’s effectiveness, especially at higher body weights.
How Your Cycle Affects Pregnancy Risk
Not every instance of unprotected sex leads to pregnancy. Your risk depends heavily on where you are in your menstrual cycle. The fertile window is the few days around ovulation, which typically occurs 10 to 16 days before your next period starts. For someone with a regular 28-day cycle, that’s around day 14.
But cycles vary, and ovulation timing isn’t always predictable. Sperm can survive inside the fallopian tubes for up to seven days, which means sex that happens days before ovulation can still result in pregnancy. It’s also possible, though less likely, to get pregnant from sex right after a period ends if you ovulate early or have a short cycle. Because of this uncertainty, emergency contraception is worth considering regardless of where you think you are in your cycle.
What to Expect After Taking Emergency Contraception
Emergency contraception pills commonly cause a few temporary side effects. Your next period may come earlier or later than usual. Light spotting between periods is normal. Some people experience nausea or, less commonly, vomiting. These effects typically resolve on their own within a day or two.
If your period is more than a week late after taking emergency contraception, take a pregnancy test. Home pregnancy tests are most reliable starting on the first day of a missed period. If you’re unsure when your period is due, wait at least 21 days after unprotected sex before testing.
Cost and Access
Under federal rules, health insurance plans are required to cover emergency contraception without a copay when it’s prescribed by a provider. Some states extend this coverage even without a prescription. If you’re paying out of pocket, generic levonorgestrel pills are the least expensive and most accessible option, available at pharmacies, some grocery stores, and online. Ulipristal acetate costs more and requires a prescription, but telehealth consultations can speed up the process. A copper IUD has a higher upfront cost but is often fully covered by insurance, and it provides years of ongoing contraception.
STI Testing After Unprotected Sex
Pregnancy isn’t the only concern after unprotected sex. If there’s any chance of exposure to a sexually transmitted infection, testing is important, but timing matters. Testing too early can produce a false negative because infections need time to become detectable.
- Chlamydia and gonorrhea: Detectable in most cases after one week, with nearly all infections caught by two weeks.
- Syphilis: A blood test catches most infections after one month. Testing at three months catches nearly all.
- HIV (blood test): Detectable in most cases after two weeks with newer antigen/antibody testing. A six-week test catches nearly all infections. Oral swab tests take longer, with most detected at one month and nearly all by three months.
If you’re concerned about HIV specifically and the exposure was very recent, post-exposure prophylaxis (PEP) is a medication that can reduce the risk of HIV infection if started within 72 hours. This is available through emergency rooms and some clinics.
Going Forward: Ongoing Contraception
Emergency contraception is designed as a backup, not a regular method. If you find yourself needing it more than occasionally, it may be worth exploring a daily or long-acting contraceptive method. The copper IUD used for emergency purposes can seamlessly become your ongoing birth control. Hormonal IUDs, implants, pills, and other methods each have their own advantages depending on your health, preferences, and lifestyle. A provider can help you find the right fit based on your situation.