Even if you make it a point to always practise safe sex, sh*t happens. Maybe the condom broke. Or maybe you forgot to take your contraceptive pill the past week. Either way, should you find yourself in these scenarios, don’t freak out—you’re not necessarily on the road to motherhood just yet. There’s time to call on emergency contraception, otherwise known as the morning-after pill.

However, you can only get it via prescription in Singapore and there are two types available: ulipristal acetate and levonorgestrel. But before we get into why you might choose one over the other, here’s the low-down on how the morning-after pill generally works.

It won’t work if you’ve already ovulated

A brief recap of biology class: ovulation occurs when a mature egg is released from your ovary and moves down the fallopian tube. It takes place about two weeks before the start of your period and you become pregnant if the egg gets fertilised by a sperm.


The morning-after pill works by delaying ovulation for at least five days, but its effectiveness depends on where you are in your menstrual cycle.

“It’s not effective if ovulation has already happened. Also, because you’re just ovulating later on in your cycle, you’ll still be at risk of pregnancy if you have unprotected sexual intercourse again,” says Dr Lim Min Yu, an obstetrician and gynecologist at the Advanced Centre for Reproductive Medicine, Gleneagles Hospital.

Levonorgestrel is more commonly prescribed as it’s up to 10 times cheaper than ulipristal acetate. However, the latter works up to 120 hours (five days) after an ‘accident’, while levonorgestrel is only effective up to 72 hours (three days) after.

Its effectiveness also depends on several external factors

Just like any other contraceptive method, the morning-after pill isn’t 100 percent effective at preventing pregnancy. Also, certain factors can affect its success rate.

“It may not work as well if you’re taking enzyme-inducing medications such as anti-epileptic drugs, antibiotics such as rifampicin or [herbs such as] St John’s Wort. Its effectiveness will also be reduced if you’re overweight or have a BMI above 26,” says Dr Lim.


If you’re on the birth control pill, the effectiveness of the morning-after pill may also be reduced. Birth control pills contain a hormone called progestogen, and according to Dr Lim, taking progestogens five days before or after consuming ulipristal acetate can reduce its effectiveness. So if you’re on the pill, you’ll be better off taking levonorgestrel.

And there are side effects

Headaches and nausea are common side effects of the morning-after pill. If you find yourself vomiting within three hours of taking it, Dr Lim recommends that a repeat dose be taken. Other side effects include a disruption to your menstrual cycle, so you may find your period arriving earlier or later by up to seven days.

The good news? The morning-after pill doesn’t have a long-term effect on your fertility and you can take it more than once per menstrual cycle. However, you should not depend on it as a form of ongoing birth control as it doesn’t offer lasting protection from pregnancy.

For more specific information, read the instructions thoroughly and be sure to follow up with your doctor if you have any questions.