Postinor 2 works for how many days: Let’s talk about a really common question people have about the emergency contraceptive Postinor-2, which is often called the morning-after pill.
The question is basically: how many days does it work for? This seems like a simple question, but the answer has a couple of parts because the wording is a little tricky. I’ll explain it all in plain language.
Postinor 2 works for how many days
First, it’s crucial to understand what we mean by “work.” Postinor-2 doesn’t work like a vaccine or a course of antibiotics that protects you for a week or two. It’s not a forcefield. Instead, it works as a single, targeted intervention for a single, specific incident.
So, when we ask “how many days does it work for,” we’re really asking two different things: one, what is the time window after sex when you can take it and it will still be effective? And two, once you take it, how long into the future does its protection last? The answers to these two questions are very, very different.
Let’s tackle the first and most important point: the window of time you have to take it after unprotected sex. The short answer is that Postinor-2 is designed to be taken within 72 hours after sex that you’re worried about. Seventy-two hours is three days. So, you have a three-day window, or 72 hours, from the moment you had unprotected sex to take the pill for it to have a chance of preventing a pregnancy.
But here’s the absolutely critical detail that you must understand: it’s not equally effective for all three of those days. This is probably the most important thing to know about how Postinor-2 works over time. Its effectiveness is highest the sooner you take it.
It’s a race against the clock happening inside your body. The pill works primarily by delaying or stopping ovulation, which is the release of an egg from your ovary. If no egg is released, then sperm can’t meet it and fertilization can’t happen.
Think of your body as being on a schedule, getting ready to release an egg. Postinor-2 is like a very strong, sudden signal that tells your body to “stop!” and pause that process. But if your body has already gotten too far along in the process and is just about to release the egg, the pill might not be strong enough to stop it.
The sooner you take the pill after sex, the more likely it is that you are taking it before your body has decided to ovulate. So, within the first 24 hours, it’s extremely effective, around 95% or so. Between 24 and 48 hours, the effectiveness starts to drop a bit. And between 48 and 72 hours, it drops further. After 72 hours, it’s considered unlikely to be effective at all.
So, while you have a three-day window to take it, you should never, ever think, “Oh, I have three days, I can wait.” You should act as if you only have a few hours. The moment you realize you need it, that is the moment you should take it. Every single hour of delay can reduce its chance of success.
Now, let’s address the second part of the question: once you take that single pill, how many days into the future does it protect you? This is where a major misunderstanding happens. The answer is: it protects you for zero days into the future. Let me say that again.
Postinor-2 offers no ongoing protection whatsoever. It only works for the instance of unprotected sex that already happened before you took the pill. It does not protect you from any sex you have after you take the pill. It’s not a regular birth control pill that you take daily to cover you for the weeks ahead.
The hormones in Postinor-2 are a very high dose, but they leave your system relatively quickly. They do their one job—trying to halt ovulation—and then they’re gone. They don’t hang around in your body creating a protective barrier. So, if you take Postinor-2 on a Monday for sex you had on Sunday, and then you have unprotected sex again on Tuesday, you are completely unprotected for that Tuesday incident.
The pill you took on Monday does nothing for Tuesday. In fact, because the pill can mess with your cycle, it might even make you more likely to ovulate at an unpredictable time soon after, so you could be at a high risk of pregnancy from any subsequent unprotected sex. This is a really important point. Postinor-2 is a one-time emergency solution for a one-time mistake. It is not a method for ongoing contraception.
This leads to another common situation. What if you have unprotected sex more than once within a short period, like over a couple of days? The dosage doesn’t change per day; it’s per incident. This is not recommended because taking these high-dose hormones frequently can really disrupt your menstrual cycle and cause more side effects, and it’s just not as effective as a reliable ongoing method.
But if you had unprotected sex on a Friday and again on a Sunday, and you only took the pill on Monday, it would only be effective for the most recent incident (the Sunday sex). It would not “cover” the Friday incident because too much time has passed. For the Friday incident, you’re already outside the 72-hour window. This gets complicated, which is why it’s always best to talk to a doctor or pharmacist if you’re in a complex situation.
Also, a related point is what happens if you vomit. If you throw up within two to three hours of taking the pill, your body might not have absorbed it. In that case, the “clock” hasn’t really started. You would need to take another pill for it to be effective. So, the protection timeline is dependent on the pill actually staying in your system.
Finally, it’s worth mentioning that for some people, specifically those with a higher body weight, there is evidence that levonorgestrel (the hormone in Postinor-2) might not work as well, and its effectiveness window might be even shorter.
For these individuals, a different type of emergency pill called ulipristal acetate (brand name EllaOne) might be a better option, as it has a 120-hour (5-day) window and may be more effective, though it often requires a prescription.
The most effective form of emergency contraception is actually the copper IUD, which can be inserted up to five days after unprotected sex and then continues to protect you for years as ongoing birth control.
Conclusion
So, to sum it all up in simple terms: Postinor-2 “works” in the sense that you can take it up to 3 days (72 hours) after a single instance of unprotected sex, but its power drops significantly with every hour that passes. Once you take it, it does not provide any protection at all for any sex you have after that moment.