For many people, the contraceptive injection (most commonly a brand like Depo-Provera) is a highly effective, long-acting, and convenient method of birth control. Administered by a healthcare provider every 12 to 13 weeks, it works by releasing a hormone called medroxyprogesterone acetate into the body. This progestin primarily works by preventing ovulation, but also thickens cervical mucus to block sperm and thins the uterine lining to prevent implantation.
While the birth control shot offers consistent protection when administered on time, there are situations where a user may worry about pregnancy. Concerns might arise from a delayed injection, the timing of a new injection, or other factors. This is where emergency contraception (EC), or the morning-after pill, comes into play as a backup option. However, understanding how the two hormonal methods interact is crucial for making an informed decision.
The Two Types of Morning-After Pills: A Critical Distinction
Not all morning-after pills are the same, and their hormonal composition determines how they interact with an existing hormonal birth control method like the injection. The two main types available are levonorgestrel and ulipristal acetate.
Levonorgestrel (e.g., Plan B One-Step, My Way, Next Choice One Dose)
Levonorgestrel-based pills are the most common type of over-the-counter morning-after pill. They contain a high dose of the synthetic hormone progestin, which works by delaying or preventing ovulation. Numerous sources, including Planned Parenthood, confirm that these pills do not interfere with the effectiveness of a contraceptive injection. The hormones do not counteract each other, and it is safe to use this type of EC if you are on the shot. You can continue your regular injection schedule immediately following its use. The primary side effect to be aware of is the potential for temporary changes in your bleeding patterns.
Ulipristal Acetate (e.g., ella)
This is a different, more potent type of emergency contraception that is available by prescription only. Unlike levonorgestrel, ulipristal acetate is an anti-progestin. Because it acts against the same type of hormone present in the contraceptive injection, there is a risk that it could reduce the effectiveness of both methods. Planned Parenthood advises that if you use ulipristal, you should avoid other hormonal birth control methods for several days after taking it. The CDC recommends using a backup barrier method, such as condoms, for at least two weeks after taking ulipristal before resuming or starting a hormonal method like the injection.
When is Emergency Contraception Necessary with the Injection?
If you are on the contraceptive injection and receive it on a regular schedule (every 12 to 13 weeks for Depo-Provera), you are already highly protected against pregnancy and likely do not need emergency contraception. However, EC is an important safety net in specific circumstances:
- Delayed Injection: If you are more than 15 weeks late for your Depo-Provera injection, you may no longer be protected and should consider EC if you have had unprotected sex.
- Starting the Injection: If you receive your first injection more than seven days after the start of your menstrual period, the CDC recommends using backup contraception for the first week. If you had unprotected sex during this initial unprotected window, EC may be necessary.
- Uncertainty: When in doubt about the timing or effectiveness of your injection, it is safer to use EC than to risk an unwanted pregnancy.
Comparing Emergency Contraception Options
| Feature | Levonorgestrel (Plan B, etc.) | Ulipristal Acetate (ella) | Copper IUD |
|---|---|---|---|
| Effectiveness Window | Up to 72 hours (3 days) after unprotected sex | Up to 120 hours (5 days) after unprotected sex | Up to 120 hours (5 days) after unprotected sex |
| Interaction with Injection | No negative interaction; considered safe | May reduce effectiveness of both; caution advised | No hormonal interaction; most effective EC |
| Accessibility | Over-the-counter; no prescription needed | Prescription required | Requires insertion by a healthcare provider |
| Ongoing Contraception | Can resume injection immediately | Need barrier method for 14 days before resuming injection | Can be kept for up to 10 years for long-term contraception |
| Efficacy | Less effective than IUD; effectiveness decreases over time | More effective than levonorgestrel, especially later | Over 99% effective; most effective EC |
What to Do After Using Emergency Contraception
Following the use of a morning-after pill while on the contraceptive injection, you should take several steps to ensure continued protection and peace of mind:
- Continue your contraception schedule: Take your next contraceptive injection at the scheduled time. If you took ulipristal (ella), follow your healthcare provider's guidance on using backup birth control before your next shot.
- Use backup protection: For at least seven days following the use of EC, it is wise to use a backup barrier method like condoms.
- Expect irregular bleeding: It is common to experience changes in your menstrual cycle, such as spotting or a later period.
- Take a pregnancy test: If you do not get a normal period within three weeks of taking the EC, it is advisable to take a pregnancy test to confirm you are not pregnant.
- Consider a more effective option: While useful, remember that emergency contraception is not as effective as regular birth control. If missed doses are a concern, a highly effective long-acting reversible contraceptive (LARC) like an IUD might be a better fit.
Conclusion: Making the Right Choice for Your Health
Navigating contraception options can be complex, and knowing what to do when things don't go according to plan is vital for reproductive health. It is safe to take a levonorgestrel-based morning-after pill, such as Plan B, while on the contraceptive injection without affecting either method's efficacy. However, the prescription pill ulipristal (ella) should be used with caution, as it can interfere with hormonal contraception. In situations where you are unsure, consulting with a healthcare professional is always the best course of action to determine the most effective path forward. The most effective form of emergency contraception is the copper IUD, which also provides long-term protection.
For more information on emergency contraception options and their use, refer to the CDC's official guidelines on emergency contraception.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Please consult a healthcare professional for personalized guidance.
