How Ella (Ulipristal Acetate) Works
Ella is a prescription-only emergency contraceptive pill containing ulipristal acetate, a selective progesterone receptor modulator. It is highly effective at preventing pregnancy when taken up to five days (120 hours) after unprotected sex. Unlike some other emergency contraceptives, Ella maintains its effectiveness over the full five-day period. Its primary mechanism is delaying or inhibiting ovulation, the release of an egg from the ovary. By delaying ovulation, Ella ensures that any sperm present—which can survive for up to five days—will have died before an egg is released for fertilization. Because its action is based on preventing ovulation, it does not interrupt an existing pregnancy.
Why Bleeding is Not a Sign of Success
Many people mistakenly believe that bleeding or spotting after taking emergency contraception is a confirmation that it worked. This is a myth. The absence of bleeding is a perfectly normal outcome after taking Ella. The ulipristal acetate in Ella directly impacts hormone levels, and the body's reaction can vary significantly from person to person. Some women may experience some irregular bleeding or spotting, but it is not required for the medication to be effective. The most reliable sign that Ella has worked is the arrival of your next period.
Common Menstrual Cycle Changes After Taking Ella
Ella can significantly affect the timing and characteristics of your next menstrual cycle. While some women's periods arrive on time, others may experience changes. Common changes include:
- Delayed period: It's common for your period to be delayed by a few days, or even up to a week. This is a normal side effect caused by the hormonal shift, and it doesn't necessarily mean the pill failed.
- Earlier period: Some women may experience their period arriving a few days earlier than expected.
- Changes in flow: Your next period could be heavier or lighter than your usual flow.
- Spotting: Light, irregular bleeding or spotting may occur before your next period.
Monitoring for Signs of Efficacy and Failure
Because bleeding is not a reliable indicator, you must look for other signs to confirm Ella's effectiveness. The most important sign is the arrival of your next period.
When to Know Ella Has Worked
- Your period arrives around the expected time, or is only slightly early or delayed.
- A negative pregnancy test result, particularly if your period is more than a week late.
Signs That Ella May Have Failed
- Your period is more than seven days late.
- Your period is unusually light or different from your norm, and you have other early pregnancy symptoms like nausea or breast tenderness.
- A positive pregnancy test.
What to Do If You Don't Bleed and Your Period is Late
If you have taken Ella and your expected period is delayed by more than seven days, it is recommended to take a pregnancy test. It is important to wait until this point for the most accurate results. Pregnancy tests detect the hormone human chorionic gonadotropin (hCG), which is only produced after a fertilized egg has implanted. Taking a test too soon could result in a false negative. If the test is positive, or if you continue to have concerns, you should contact a healthcare provider.
There are also rare but serious side effects to be aware of. If you experience severe lower abdominal pain approximately 3 to 5 weeks after taking Ella, this could be a sign of an ectopic pregnancy. An ectopic pregnancy is a life-threatening condition that requires immediate medical attention. Seek emergency medical care immediately if you suspect an ectopic pregnancy.
Ella vs. Plan B: A Comparison Table
| Feature | Ella (Ulipristal Acetate) | Plan B One-Step (Levonorgestrel) |
|---|---|---|
| Active Ingredient | Ulipristal acetate | Levonorgestrel |
| Availability | Prescription only | Over-the-counter (no prescription) |
| Timeframe for use | Up to 120 hours (5 days) after unprotected sex | Up to 72 hours (3 days) after unprotected sex |
| Effectiveness Window | Consistent effectiveness throughout the 120-hour window | Decreases in effectiveness the longer you wait within the 72-hour window |
| Impact on Ovulation | Delays or prevents ovulation, even when it is imminent | Delays or prevents ovulation; may not work if ovulation has already occurred |
| Body Weight Considerations | More effective for individuals with a higher BMI (over 25) compared to Plan B | Less effective for individuals with a higher BMI (over 25 or 30) |
| Breastfeeding | Manufacturer advises against use or requires pumping and discarding milk | May be compatible with breastfeeding, but consult a doctor |
Conclusion
It is important to remember that not bleeding after taking Ella is normal and does not mean the medication was unsuccessful. Ella works by delaying ovulation, and its hormonal effects can alter your next menstrual cycle. The most accurate way to know if Ella has worked is to wait for your next period, which may be slightly delayed. If your period is more than a week late, take a pregnancy test. If you experience any severe symptoms, such as severe abdominal pain, seek immediate medical attention. For ongoing contraception, consult a healthcare provider to find a method that best suits your needs.
For more information on emergency contraception, you can visit the Mayo Clinic website.
