Levonorgestrel vs EllaOne are two of the most popular and effective emergency contraceptive pills available today. When unprotected sex or contraceptive failure happens, knowing which pill to choose can make all the difference. Both help prevent pregnancy safely, but they differ in timing, effectiveness, and how they work in your body.

When it comes to emergency contraception, having clear and accurate information is crucial for making a timely and informed decision. The need for it can arise unexpectedly, and knowing your options ahead of time can reduce stress and ensure you choose the most effective method for your situation. Two of the most common oral emergency contraceptive pills available are those containing Levonorgestrel and ulipristal acetate, sold under the brand name EllaOne. While both are designed to prevent pregnancy after unprotected sex or contraceptive failure, they have key differences in how they work, their effectiveness windows, and who can use them. This guide will provide a detailed comparison to help you understand the nuances between these two options.

What Is Emergency Contraception?

Before diving into the specifics of each pill, it’s important to understand what emergency contraception (EC) is—and what it isn’t. EC, often called the “morning-after pill,” is a safe and effective way to prevent pregnancy after sex. It works primarily by delaying or preventing ovulation, the release of an egg from the ovary. If an egg isn’t released, sperm cannot fertilize it, and pregnancy cannot occur.

It’s a common misconception that EC is an abortion pill. This is incorrect. Emergency contraception works before a pregnancy is established. It will not harm an existing pregnancy or cause an abortion. It is a backup method, not a regular form of birth control, and it does not protect against sexually transmitted infections (STIs).

An Introduction to Levonorgestrel

Levonorgestrel is a synthetic hormone that has been used in various forms of contraception for decades. As an emergency contraceptive, it is the most widely available and well-known option. You might recognize it under brand names like Plan B One-Step, Aftera, My Way, and others.

How Does Levonorgestrel Work?

The primary mechanism of action for Levonorgestrel is delaying or inhibiting ovulation. When you take the pill, the dose of progestin hormone signals your body to hold off on releasing an egg. For it to be effective, it must be taken before the luteinizing hormone (LH) surge begins—the hormonal signal that triggers ovulation within the next 24 to 36 hours. If the LH surge has already started or ovulation has occurred, it is unlikely to be effective.

Additionally, some research suggests it may also work by thickening cervical mucus, making it more difficult for sperm to travel and reach an egg if one has been released.

The Window of Effectiveness

Timing is critical when using this form of emergency contraception. It is approved for use up to 72 hours (3 days) after unprotected intercourse. However, its effectiveness is highest when taken as soon as possible.

• Within 24 hours: It is most effective, preventing an estimated 95% of expected pregnancies.
• Between 24 and 48 hours: Effectiveness decreases slightly.
• Between 48 and 72 hours: Effectiveness drops further, though it still offers a significant chance of preventing pregnancy compared to taking no action.

After the 72-hour mark, its ability to prevent pregnancy diminishes significantly, and an alternative method should be considered if possible.

Factors That Can Affect Effectiveness

One of the most important factors influencing the effectiveness of Levonorgestrel is body weight and Body Mass Index (BMI). Studies have shown that its efficacy may be reduced in individuals with a BMI of 25 or higher, and it may be ineffective in those with a BMI over 30. This is a crucial consideration for many people when choosing an emergency contraceptive. While it may still offer some protection, individuals with a higher BMI should be aware of this potential limitation and may want to consider other options.

An Introduction to EllaOne (Ulipristal Acetate)

EllaOne is a newer generation of emergency contraceptive pill. Its active ingredient is ulipristal acetate, which is a selective progesterone receptor modulator (SPRM). This means it works on the progesterone receptors in the body but in a different way than Levonorgestrel.

How Does EllaOne Work?

Like its counterpart, EllaOne’s primary function is to delay or prevent ovulation. However, its key advantage lies in its ability to remain effective even after the LH surge has begun. While Levonorgestrel loses its efficacy once the LH level starts to rise, ulipristal acetate can still postpone ovulation, providing a longer and more reliable window of opportunity to prevent pregnancy. It works by blocking the effects of progesterone, which is essential for ovulation and for preparing the uterine lining for pregnancy. By interfering with this process, it effectively puts ovulation on hold.

The Window of Effectiveness

EllaOne has a longer approved window of use compared to Levonorgestrel. It is effective for up to 120 hours (5 days) after unprotected sex. Importantly, its effectiveness does not decline significantly over this five-day period, making it a more consistent option if you are unable to take a pill immediately. This extended window makes it a valuable choice for individuals who may not realize they need EC right away or face delays in accessing it.

Factors That Can Affect Effectiveness

EllaOne is also impacted by body weight, but to a lesser degree than Levonorgestrel. Research indicates that it remains more effective than Levonorgestrel in individuals with a higher BMI. While its efficacy may see a slight reduction in those with a BMI over 30, it is still considered the more effective oral option for this group compared to Levonorgestrel, which may be completely ineffective. For individuals with a BMI over 35, the copper IUD is recommended as the most effective form of emergency contraception.

Comparing Side Effects

Both medications can cause side effects, though most people experience them mildly, if at all. The side effects are quite similar for both pills because they both work on the body’s hormonal systems.

Common side effects for both include:

• Headache
• Nausea and vomiting
• Abdominal or menstrual-like cramps
• Dizziness
• Fatigue
• Breast tenderness
• Changes to your next period (it may come earlier, later, or be heavier than usual)

A crucial point regarding side effects: if you vomit within three hours of taking either pill, you should contact a healthcare provider or pharmacist. You may need to take another dose, as the initial one may not have been fully absorbed.

Availability and Accessibility

How you can get these pills is another key difference between them.

Levonorgestrel Availability

Levonorgestrel-based emergency contraception is widely available over-the-counter (OTC) in many countries, including the United States. This means you can purchase it directly from a pharmacy or drugstore shelf without a prescription and with no age restrictions. This ease of access is a major advantage, as it allows for immediate action without needing to schedule a doctor’s appointment.

EllaOne Availability

In contrast, EllaOne is available by prescription only in the United States and many other countries. This means you must consult with a healthcare provider to get it. This can be a significant barrier, especially when time is of the essence. However, the rise of telehealth services has made it easier to obtain a prescription quickly online. A doctor can assess your situation, determine if EllaOne is the right choice, and send the prescription to a local pharmacy for you. In some countries, like the UK, it may be available from a pharmacist after a brief consultation without needing to see a doctor first.

Which Pill Should You Choose? A Head-to-Head Summary

Choosing between the two depends on three main factors: how long it has been since the unprotected intercourse, your BMI, and accessibility.

When to Choose Levonorgestrel:

• It has been less than 72 hours since unprotected sex.
• You have a BMI under 25.
• You need to get a pill immediately and cannot wait for a prescription.

When to Choose EllaOne:

• It has been between 72 and 120 hours since unprotected sex.
• You are closer to your ovulation time (though this can be hard to predict).
• You have a BMI of 25 or higher.
• You want the most effective oral option available within the 5-day window.

Important Considerations After Taking EC

After taking any emergency contraceptive pill, it’s wise to take a pregnancy test if your period is more than a week late or if you experience any signs of pregnancy. Remember that your next cycle may be irregular, which is normal.

It’s also important not to use hormonal birth control (like the regular pill, patch, or ring) for at least five days after taking EllaOne, as it can reduce its effectiveness. Your doctor or pharmacist can advise you on when to restart your regular contraception and the need for a backup method, like condoms, in the meantime.

The Most Effective EC: The Copper IUD

While this guide focuses on oral contraceptives, it’s worth noting that the most effective form of emergency contraception is the copper IUD. When inserted within five days of unprotected sex, it is over 99% effective at preventing pregnancy. It works by creating an inflammatory reaction in the uterus that is toxic to sperm and eggs, preventing fertilization. As an added benefit, it can remain in place and provide highly effective, long-term contraception for up to 10-12 years. This option is ideal for those seeking the most reliable EC method that also doubles as ongoing birth control.

Conclusion: Making an Empowered Choice

Understanding the differences between Levonorgestrel and EllaOne empowers you to make the best decision for your health and circumstances. While Levonorgestrel offers the benefit of immediate, over-the-counter access, its shorter time window and reduced effectiveness at higher body weights are important limitations. For many, the superior and more consistent efficacy across a longer time frame makes the prescription-based EllaOne a more reliable choice, provided you can access it in time. Consulting with a healthcare provider or a telehealth service can quickly help you determine the most appropriate and effective method for your specific situation, ensuring you have peace of mind when you need it most.