Take emergency contraception as soon as possible after unprotected sex: levonorgestrel pills are labeled for use within 72 hours, ulipristal acetate works up to 120 hours, and a copper IUD placed within 5 days is the most effective option of all. Every hour of delay lowers your odds, so act now rather than waiting for a “better” method. None of these options will end an existing pregnancy.
TL;DR:
- Taking emergency contraception as soon as possible maximizes effectiveness, with levonorgestrel within 72 hours, ulipristal within 120 hours, and copper IUD within five days.
- Ulipristal acetate remains more effective later in its window and is less impacted by higher body weight compared to levonorgestrel.
- Both pills primarily delay ovulation and do not terminate an existing pregnancy, making timing critical for success.
- Vomiting within a few hours of taking the dose requires prompt re-administration, and delayed periods over seven days late should prompt pregnancy testing.
- Accessing contraception through pharmacy stock or same-day telehealth options can significantly reduce delay and increase chances of success.
Table of Contents
- Types of emergency contraception and their timing windows
- How timing affects effectiveness and what your weight has to do with it
- How emergency contraception works and what it does not do
- What to do right now and in the days that follow
- Getting it fast: pharmacy, clinic, and telehealth options
- Side effects, period changes, and when to call a doctor
- Getting a same-day prescription without the wait
- A clinician’s take on acting fast
- Same-day care when timing matters most
- FAQ
- Sources
Types of emergency contraception and their timing windows
Three main options exist, and each has a different window and a different way to get it.
- Levonorgestrel (OTC pill): Available without a prescription at most pharmacies, labeled for use within 72 hours of unprotected sex, though some clinicians discuss its use slightly past that window when nothing else is available.
- Ulipristal acetate (UPA, prescription only): Works up to 120 hours and is generally the better choice the closer you are to the five-day mark, since it holds its effectiveness longer than levonorgestrel.
- Copper IUD: Insertion within five days of unprotected sex is the most effective emergency method, with the added benefit of ongoing contraception afterward, though it requires a same-day or next-day clinic visit for placement.
The pill you can get fastest is often the right call. Waiting two extra days to track down a prescription for UPA when levonorgestrel is sitting on a pharmacy shelf can work against you, especially early in the window.
How timing affects effectiveness and what your weight has to do with it
Emergency contraception works best when taken immediately, and effectiveness declines with every passing hour rather than dropping off sharply at a single cutoff.
One in five pregnancies after unprotected sex may still be prevented by taking emergency contraception promptly, but clinical guidance is consistent that delay reduces that protection, which is why reproductive health organizations frame advance provision, keeping a dose on hand before you need it, as a meaningful way to close the gap.
- Ulipristal acetate maintains higher effectiveness later in its window than levonorgestrel does in its own window.
- Evidence suggests levonorgestrel may be less effective in people with higher body weight, while UPA appears to delay ovulation more consistently across weight ranges.
- If you are past the first day or two, or you know your BMI falls in a higher range, UPA or a copper IUD is generally the stronger choice when either is reachable in time.
If neither is quickly accessible and you are still within 72 hours, taking levonorgestrel now is usually better than waiting for a prescription. For a deeper look at how the pill and the IUD stack up for emergency use, see our comparison of pill versus IUD options.
How emergency contraception works and what it does not do
Levonorgestrel and ulipristal acetate work primarily by delaying or inhibiting ovulation, which means they only help before an egg has been released. Once ovulation has already happened, oral emergency contraception is not effective, which is part of why timing matters so much.
- Neither pill interrupts or ends a pregnancy that has already been established.
- The copper IUD works differently, likely affecting the egg and sperm directly, and its mechanism is part of why it remains effective even later in the five-day window.
- If you think you might already be pregnant from an earlier encounter, emergency contraception will not change that outcome.
What to do right now and in the days that follow
- Take the levonorgestrel pill you have on hand immediately if you are within 72 hours; if you can reach a prescriber or clinic quickly, ask about ulipristal acetate or a copper IUD instead.
- If you vomit within 2 to 3 hours of taking the dose, contact a clinician about repeating it, since the medication may not have fully absorbed.
- Watch your next period. If it is more than seven days late, take a pregnancy test and follow up with a provider.
- Avoid further unprotected sex and talk with a clinician about starting or resuming regular birth control, since UPA can interact with hormonal methods started too soon afterward.
- Seek care right away for severe abdominal pain, which can signal a different medical issue, or for persistent vomiting that prevents you from keeping a dose down.
Pro Tip: Keep a dose of emergency contraception at home before you need it. Advance provision removes the scramble to find a pharmacy or appointment at the worst possible moment.
Getting it fast: pharmacy, clinic, and telehealth options
Levonorgestrel sits on pharmacy shelves without a prescription, which makes it the fastest option for most people. Ulipristal acetate requires a prescription, and that single extra step is often what costs people the most time.
- Most pharmacies stock levonorgestrel over the counter, no appointment or ID required for purchase.
- A telehealth visit can produce a same-day prescription for ulipristal acetate, cutting out the wait for an in-person appointment.
- Coverage varies by plan, but many insurance plans cover emergency contraception at low or no out-of-pocket cost, and it is worth checking before paying full price.
- If your local pharmacy is out of stock or a clinic has no same-day openings, an urgent care visit, a telehealth prescriber, or a clinic that places copper IUDs are all reasonable backup routes.
Side effects, period changes, and when to call a doctor
Most people tolerate emergency contraception well, with nausea, headache, abdominal discomfort, dizziness, and temporary changes to the timing of your next period being the most commonly reported effects.
If your period is more than 7 days late, take a pregnancy test rather than assuming the delay is just a side effect.
- Your next period may arrive earlier or later than usual, and flow can be lighter or heavier than normal.
- Mild nausea is common and usually passes within a day; persistent vomiting is not typical and deserves a call to your clinician.
- Severe or worsening abdominal pain needs prompt medical attention, since it can occasionally point to a different condition such as an ectopic pregnancy. If nausea is the main issue, this guide to managing morning sickness-style nausea covers remedies worth trying before you decide a repeat dose is needed.
Getting a same-day prescription without the wait
A virtual visit for emergency contraception typically takes a short conversation about your timing, your medical history, and whether vomiting or a missed dose has come up, after which a clinician can send a prescription for ulipristal acetate or talk through repeat dosing if your first dose did not stay down.
- Same-day appointments are available, so a prescription for ulipristal acetate does not have to wait for the next open slot at a local clinic.
- Licensed clinicians on the platform can also answer timing questions, advise on vomiting within the critical window, and arrange prescription delivery.
- Follow-up contraception counseling is part of the same visit, so you are not left guessing about next steps once the emergency dose is handled.
Pro Tip: If you know access near you is unreliable, ask your provider about advance provision so you already have emergency contraception on hand before you need it.
A clinician’s take on acting fast
The single biggest factor in whether emergency contraception works is not which pill you take. It is how quickly you take it. I would rather see someone take whatever is in reach within the first day than wait for a “perfect” option two days later. If your period is late or something feels off afterward, do not wait that out either: get checked.
— Bryan
Same-day care when timing matters most
When every hour counts, waiting days for an appointment is its own kind of risk. We built our platform around same-day virtual visits so you can get a prescription for ulipristal acetate, ask about repeat dosing after vomiting, or start planning your ongoing birth control without sitting on a waitlist.
- A same-day telehealth visit can get you a prescription for ulipristal acetate sent for delivery rather than requiring an in-person pharmacy trip.
- The same visit covers follow-up questions about starting or resuming regular contraception once the emergency dose is handled.
If you want same-day help, our birth control page is the place to start.
This article is general information, not a substitute for advice from a qualified doctor. Consult a qualified healthcare professional about your own circumstances before acting on anything here.
FAQ
How late is too late for the morning after pill?
Levonorgestrel is labeled for use within 72 hours of unprotected sex, while ulipristal acetate remains effective up to 120 hours. Past five days, a copper IUD is the option to ask about, since oral emergency contraception is not labeled for use beyond that window.
What cancels out the morning after pill?
Vomiting within a few hours of taking the dose can prevent full absorption, and product labeling advises contacting a clinician about repeating the dose in that case. Starting certain hormonal contraception too soon after taking ulipristal acetate can also reduce its effectiveness, so timing the switch matters.
What causes the morning after pill to fail?
Taking it too long after unprotected sex is the most common reason it fails, since effectiveness declines the longer you wait. Higher body weight has also been linked to reduced effectiveness for levonorgestrel specifically, which is one reason some clinicians recommend ulipristal acetate or a copper IUD when either is accessible.
How many hours does the morning after pill cover?
Levonorgestrel is labeled for 72 hours, and ulipristal acetate covers 120 hours. Both work best the sooner you take them rather than at any point right up against the labeled limit.
Sources
- Morning After Pill: Emergency Contraception & Side Effects — Cleveland Clinic
- Emergency Contraception — CDC
- ella (ulipristal acetate) FDA labeling
- DailyMed - levonorgestrel tablet label
- Morning-after pill — Mayo Clinic
.svg)
.svg)
.svg)
.svg)
