Plan B versus Ella: How Are They Different and Which Emergency Contraception Is Better?

Plan B versus Ella: How Are They Different and Which Emergency Contraception Is Better?

At a glance

So what exactly is Plan B? Is it a type of emergency contraception or a brand name? Why does every morning-after pill get referred to as “plan B” so often? What is the difference between Plan B and Ella, which one is better?  

All of these are valid questions and we hope to clear some of the confusion up.

In this article, we will be discussing the major differences between Plan B and Ella and which emergency contraceptive is best for you.

Differences Between Plan B and Ella

Here are the 3 main differences between Plan B and Ella:

1. Main Active Ingredient

The most significant difference between Plan B and Ella is the main active ingredient present in the emergency contraception pill.

The main active ingredient in Plan B is levonorgestrel, a synthetic form of progesterone. As a synthetic hormone, levonorgestrel is able to mimic progesterone which tricks the body into thinking that it is pregnant. This stops the ovaries from releasing an egg and prevents ovulation from happening.

The main active ingredient in Ella is ulipristal acetate, a form of Selective Progesterone Receptor Modulator (SPRM). While ulipristal acetate achieves the same goal as levonorgestrel, which is to prevent or delay ovulation from occurring, it takes a different route to the same destination. Instead of mimicking progesterone, ulipristal acetate suppresses progesterone instead which can delay ovulation for up to 5 days - this gives the sperm plenty of time to die off before the egg is released.

Depending on what stage you are at in your menstrual cycle, Ella® can also thin your uterine slightly which can further decrease the likelihood of pregnancy as it makes it harder for the fertilized egg to implant itself.

2. Effectiveness And Time Frames

Another difference between Plan B and Ella is its effectiveness rates and how long you would have to take the emergency contraceptive before its effectiveness begins to diminish

If you choose to take Plan B (or any other levonorgestrel-based emergency contraception pill), it is recommended that you take the pill within 72 hours (or 3 days) of having  unprotected sex. In a study carried out by Princeton University, it was found that Plan B had an effectiveness rate of 95% when taken within 24 hours of having unprotected sex, and an average effectiveness rate of 88% within 72 hours.

Ella, on the other hand, beats Plan B in terms of its effectiveness rates and has a longer time frame that retains its high effectiveness rates. In a study carried out by the World Health Organisation, Ella (and other ulipristal acetate-based emergency contraception pills) were found to have an effectiveness rate of 98.8% when within 24 hours of having unprotected sex, and can be still be as effective when taken between 72 to 120 hours (or 5 days) after having unprotected sex.

It is still recommended that all emergency contraceptive pills be taken as soon as possible, to ensure that unwanted pregnancy does not occur.  

3. BMI Restrictions

Another important difference between Plan B and Ella is the possible limitation of its effectiveness when it comes to treating women with higher BMIs (Body Mass Index).

According to Princeton University, there was evidence to suggest that Plan B (or other levonorgestrel-based emergency contraception pills) were less effective for women with a BMI of 26 and above.

Ella on the other hand still retained its effectiveness rates for women with BMIs up to 35.  

Where To Get Emergency Contraception In Singapore

While emergency contraception or morning after pills can often be referred to as “plan B pills”, the sale of the branded medication Plan B or Plan B One-Step is not available in Singapore as an over-the-counter medication.

If you require emergency contraception pills in Singapore, you will need to consult a doctor and get a prescription. Commonly prescribed emergency contraception pills in Singapore are usually Postinor-2 (a levonorgestrel-based emergency contraception pill similar to Plan B One Step) and Ella.

The Takeaway

If you’ve recently had unprotected sex and require emergency contraceptive pills, you can consult one of our doctors. Here at Zoey, we understand that emergency contraception is a time-sensitive prescription and will have your prescription delivered to you within the 4-hour delivery promise at no additional cost.

Find out what your BMI indicates

Your BMI indicates that you may be
BMI provides an estimate of weight classification. For a thorough analysis of your weight and medical options, arrange a teleconsult with a Noah doctor.

*Medical treatment may not be appropriate for you even if you have a high BMI
Your estimated weight loss in 1 year*
*In a 56-week trial with 3,731 non-diabetic overweight (BMI ≥27) or obese (BMI ≥30) participants, those who finished (1,812 patients) lost an average of 9.2% body weight with Saxenda, alongside diet and exercise.
medically reviewed by
Written by our
Editorial Team
last updated
April 29, 2024

Articles featured on Zoey are for informational purposes only and should not be constituted as medical advice, diagnosis or treatment. If you have any medical questions or concerns, please talk to your healthcare provider. If you're looking for a healthcare provider, click here.


“Emergency Contraception.” World Health Organization, World Health Organization, (Link) 2021. Emergency contraception: Effectiveness of emergency contraceptives. [online] Available at: <*> (Link) 2021. Emergency Contraception: ella or progestin-only?. [online] Available at: <> (Link)

Emergency Contraception
Sexual Health
Emergency Contraception
From $25/Month