
Emergency contraceptives offer the last chance to stop an unintended pregnancy before it happens. They can be used after having unprotected sex, if the contraceptive method fails (for example, the condom breaks or you miss a birth control pill), or after a sexual assault.
There are two types of emergency contraceptives: the morning-after pill and the copper IUD.
Read on to find out more about emergency contraceptives and whether they may be right for you.
First things first: what’s the risk of getting pregnant if you have unprotected sex or if your contraceptive method fails?
This will totally depend on where you are in your cycle.
You’re not fertile every day of your cycle. You’re only fertile for an average of 6 days each cycle, during your ovulatory phase—this is from about five days before ovulation until 24 hours after ovulation occurs. While an egg can only be fertilized by sperm for 12–24 hours after ovulation, sperm can survive in the cervix for up to five days after entering your body, potentially leading up to a pregnancy.
This means that there are several days in your cycle in which, even if you have unprotected intercourse, you’re not at risk of getting pregnant.
Whether you need emergency contraception or not will depend on where you are in your cycle when you have intercourse.
How does the morning-after pill work?
The morning-after pill works by blocking or delaying ovulation. It stops the production of the LH hormone, which then prevents the egg from being released to the fallopian tubes. If ovulation doesn’t happen, sperm can’t come in contact with an egg.
The morning-after pill is more effective in the pre-ovulatory part of your fertile window (before ovulation has occurred). If you ovulate before taking the pill, it’s significantly less likely to work. This is why it should be taken as quickly as possible after unprotected intercourse.
There are currently two types of morning-after pills on the market sold under different brand names.
- Levonorgestrel, which is a single-tablet, progestin-only pill (progestin is a form of synthetic progesterone). It’s the most used, and it’s highly effective if you take it up to 96 hours after sexual intercourse (the sooner you take it, the more effective it will be). In most countries, it’s available over-the-counter from a pharmacist without a prescription.
- The ulipristal acetate pill (aka anti-progestin pill) is considered the most effective type of emergency contraceptive pill. It can work if taken up to 120 hours after sex (again, the sooner, the better). It’s available by prescription in more than 50 countries.
What are the side effects of the morning-after pill?
Generally, there are no severe or long-term side effects from taking the emergency contraceptive pill, but it can cause:
- Fatigue
- Nausea
- Vomiting (if it occurs within 2 hours of taking the pill, talk to a healthcare provider, as you may need another dose)
- Breast pain
- Headache
- Mid-cycle bleedings
- Changes to your next period – it can be earlier, later, or more painful than usual
- Anovulatory cycles
- In some cases, the appearance of cysts has been reported.
Talk to your medical practitioner if your symptoms don’t go away after a few days, if you experience very heavy bleeding, or your next period is more than 7 days late, as it can be a sign of pregnancy.
How often can I take the morning-after pill?
The morning-after pill is not intended to be taken as a regular form of birth control. According to the World Health Organization, frequent use of emergency contraception can result in increased side effects, such as menstrual irregularities.
Talk to a health care professional for advice on what birth control methods may be more appropriate and more effective for you.
Please consider that the morning-after pill doesn’t offer continuous protection against pregnancy. If you have unprotected sex at any time after taking the pill (and you are in your fertility window), you can become pregnant.
The copper IUD: another alternative for emergency contraception

The intrauterine device (IUD) is a small, T-shaped plastic and copper device that’s inserted into your uterus by a doctor or nurse.
Copper IUDs are the most effective form of emergency contraception. Unlike the morning-after pill, they can prevent pregnancy both before and after ovulation.
They work by a) preventing sperm from fertilizing an egg or b) preventing a fertilized egg from implanting in the uterus. You can choose to have the IUD left in as an ongoing birth control method.
The IUD shouldn’t be inserted if there’s a chance that you may already be pregnant. Side-effects are rare but can include pain and spotting, infection, damage to the uterus, the IUD expelled through the vagina, and heavier, longer, or more painful periods if you continue to use it as your birth control method.
Please note that hormonal IUDs, which are different from copper ones, don’t work as emergency contraception.
Talk to your OBGYN or primary care provider to get more information about your options and how to make emergency contraception as effective and as safe as possible.

New to Menstrual Cycle Awareness and not sure where to start?
Download my free guide with 3 simple steps to get to know your cycle.
You’re signing up to receive emails from Carmen Lorenzana