Yes, you can take the morning after pill while breastfeeding. The most common type, containing levonorgestrel (sold as Plan B and generics), is considered safe for nursing mothers and their babies. A fully breastfed infant receives only about 0.1% of the mother’s dose through breast milk, and studies have found no measurable effects on infant health, growth, or development.
That said, the two types of morning after pill have different recommendations for breastfeeding, and the timing of your next feeding matters. Here’s what you need to know.
Levonorgestrel (Plan B) Is the Preferred Option
Levonorgestrel is the active ingredient in Plan B One-Step and its generic equivalents. It’s available over the counter without a prescription and is the go-to choice for breastfeeding women who need emergency contraception. The CDC classifies it as Category 2 for use during lactation, meaning the benefits generally outweigh any theoretical risks.
Drug levels in breast milk peak between one and three hours after you take the pill, then drop quickly. After a standard dose, milk levels fall to very low concentrations by about four hours. To minimize what your baby receives, you can wait 3 to 4 hours after taking the pill before your next feeding. This isn’t strictly required for safety, but it’s a simple precaution if you want to reduce exposure further.
A study comparing breastfed infants whose mothers used levonorgestrel emergency contraception with infants whose mothers did not found no significant differences in weight, length, head circumference, or developmental milestones. Mothers in the study also reported no noticeable change in their milk supply.
Ulipristal (Ella) Requires a Longer Break
The other morning after pill, ulipristal acetate (sold as Ella), works differently and requires a prescription. It’s more effective than levonorgestrel, especially between 72 and 120 hours after unprotected sex, but it comes with a bigger trade-off for breastfeeding mothers.
The manufacturer recommends avoiding breastfeeding for 7 days after taking ulipristal. Some lactation databases suggest a shorter window of 24 hours may be sufficient, but the more conservative one-week recommendation is what most prescribers follow. During that time, you would need to pump and discard your milk to maintain supply, then resume nursing once the waiting period is over.
If you’re exclusively breastfeeding and don’t want to interrupt nursing for a full week, levonorgestrel is the simpler choice. But if you’re past the 72-hour window where levonorgestrel works best, ulipristal may still be worth considering since it remains effective up to five days after unprotected sex.
The Copper IUD: A Hormone-Free Alternative
If you want to avoid hormones entirely, the copper IUD is the most effective form of emergency contraception available. It prevents pregnancy in more than 99.9% of cases when placed within five days of unprotected sex, which is roughly ten times more effective than either pill. Because it’s hormone-free, it has no effect on breast milk composition or supply.
The copper IUD does require a clinic visit for insertion, which makes it less convenient in a time-sensitive situation. But it doubles as long-term contraception for up to 10 years, which can be appealing for someone who also wants reliable birth control while breastfeeding.
Body Weight Can Affect How Well the Pills Work
This is worth knowing regardless of breastfeeding status: both morning after pills become less effective at higher body weights. Levonorgestrel starts losing efficacy at a lower weight threshold than ulipristal. For women with a BMI of 25 or above, ulipristal tends to be the more reliable oral option. For women with a BMI of 30 or above, the copper IUD is the most dependable choice.
That said, the American College of Obstetricians and Gynecologists is clear that overweight and obese women should not be discouraged from using levonorgestrel if it’s what’s available. Reduced effectiveness is still better than no emergency contraception at all.
Practical Timing Tips
If you choose levonorgestrel (Plan B), here’s a straightforward approach: take the pill right away, since it works best the sooner you use it. If you can, nurse your baby just before taking it or plan to wait about 3 to 4 hours before the next feeding. If your baby needs to eat sooner than that, the amount of drug in your milk is still extremely small and unlikely to cause any harm.
If you choose ulipristal (Ella), pump and store enough milk beforehand to cover feedings during the waiting period, or plan to use formula temporarily. Pump on your regular nursing schedule during the break to protect your supply, but discard that milk. Resume breastfeeding after the recommended waiting period has passed.
Neither pill has been shown to cause a lasting drop in milk production. Any temporary fluctuation you notice is more likely related to stress, hydration, or changes in feeding frequency during a pumping break than to the medication itself.