Important Disclaimer
This article is for informational purposes only and does not constitute medical advice. Emergency contraception is time-sensitive. Always consult with a qualified healthcare provider or visit a clinic like Planned Parenthood to determine the best and safest option for your individual health circumstances.
The Critical 5-Day Window
After unprotected intercourse, there is a limited window of up to five days (120 hours) to use emergency contraception (EC) to prevent pregnancy [1.2.2]. The effectiveness of different methods varies significantly within this timeframe, especially after the 72-hour (3-day) mark has passed. Acting quickly is crucial, as it provides more options and generally higher success rates [1.2.3].
What Pill Can I Take After 4 Days? Your Primary Option
At 4 days (96 hours) after unprotected sex, the most effective emergency contraception pill available is ulipristal acetate, sold under the brand name ella® [1.2.2, 1.2.4].
Unlike other morning-after pills, such as those containing levonorgestrel (e.g., Plan B One-Step), ulipristal acetate was specifically designed to maintain its effectiveness for up to 120 hours [1.3.2].
How Ulipristal Acetate (ella®) Works
Ulipristal acetate is a selective progesterone receptor modulator. Its primary function is to delay or inhibit ovulation, even when taken close to when ovulation is expected to occur [1.3.1, 1.4.8]. By preventing the release of an egg from the ovary, it prevents fertilization. It is important to note that EC pills like ella® do not terminate an existing pregnancy [1.2.3].
Effectiveness and Access
Studies have shown that ulipristal acetate is significantly more effective than levonorgestrel pills between 72 and 120 hours after unprotected sex [1.3.2]. It is available only by prescription from a healthcare provider [1.2.3, 1.2.7]. You can obtain a prescription from:
- Your primary care doctor or gynecologist
- An urgent care center
- A local family planning clinic, such as Planned Parenthood [1.7.1]
- Online telehealth services, which can send a prescription to a local pharmacy or offer mail delivery [1.7.2, 1.7.3, 1.7.5]
A Non-Pill Alternative: The Copper IUD
The most effective form of emergency contraception overall is the copper intrauterine device (IUD), also known as Paragard [1.2.1, 1.5.4]. It can be inserted by a healthcare professional up to 5 days after unprotected intercourse and is over 99% effective at preventing pregnancy [1.5.4].
The copper IUD works by creating an inflammatory reaction inside the uterus that is toxic to sperm and eggs, preventing fertilization [1.5.2]. A major advantage is that it can remain in place and serve as a highly effective long-term birth control method for up to 10 years [1.2.1]. Unlike hormonal pills, its effectiveness is not reduced by body weight [1.2.1, 1.4.4].
Comparison of Emergency Contraception Options
| Feature | Ulipristal Acetate (ella®) | Levonorgestrel (Plan B, etc.) | Copper IUD (Paragard) |
|---|---|---|---|
| Effective Window | Up to 120 hours (5 days) [1.2.4] | Best within 72 hours (3 days), can be used up to 5 days with reduced efficacy [1.2.2] | Up to 120 hours (5 days) [1.5.4] |
| Effectiveness | Maintains high effectiveness up to day 5 [1.3.2] | Effectiveness decreases significantly after day 3 [1.4.2, 1.4.6] | Over 99% effective [1.5.4] |
| Prescription Needed? | Yes [1.2.7] | No, available over-the-counter [1.2.2] | Yes, requires clinic visit for insertion [1.2.1] |
| Impacted by Weight? | May be less effective in individuals over 195 lbs [1.2.2] | May be less effective in individuals over 165 lbs [1.2.2, 1.2.8] | No [1.2.1, 1.5.2] |
What About Levonorgestrel Pills (Plan B)?
Levonorgestrel-based pills like Plan B One-Step, Take Action, and My Way are widely available over the counter [1.2.8]. While you can technically take them up to five days after intercourse, their effectiveness drops significantly after 72 hours (3 days) [1.4.6]. Therefore, at the 4-day mark, a levonorgestrel pill is not the recommended or most effective oral option [1.4.2]. Ulipristal acetate (ella®) is superior in this later timeframe [1.3.2].
Potential Side Effects
Emergency contraception is generally safe, but some people may experience side effects. For ulipristal acetate (ella®), the most common side effects are mild and may include:
- Headache [1.6.6]
- Abdominal or menstrual pain (cramps) [1.6.1, 1.6.6]
- Nausea [1.6.6]
- Changes to your next menstrual period (it may come earlier or later) [1.6.1]
- Dizziness or tiredness [1.6.6]
If you vomit within three hours of taking the pill, you should contact a healthcare professional to see if you need another dose [1.2.5].
Conclusion: Your Best Options After Day 3
When facing the question of what pill to take after 4 days, the clear answer is ulipristal acetate (ella®), which requires a prescription. It is demonstrably more effective than over-the-counter options in the 72-to-120-hour window. However, the most effective method of all is the copper IUD, which also provides long-term contraception. Given the time-sensitive nature of this decision, it is imperative to contact a healthcare provider or a telehealth service as soon as possible to secure a prescription for ella® or schedule an IUD insertion.
For more information, you can visit Planned Parenthood's page on emergency contraception.
