You can breastfeed immediately after taking Plan B. No waiting period is medically necessary. The amount of levonorgestrel (the active ingredient in Plan B) that passes into breast milk is minimal, and major health organizations including the Academy of Breastfeeding Medicine and the World Health Organization consider it compatible with breastfeeding.
What the Package Insert Says vs. What the Evidence Shows
This is where the confusion starts. Some product packaging suggests avoiding breastfeeding for 8 hours after taking levonorgestrel emergency contraception. However, the Breastfeeding Network, a UK-based clinical charity, states directly that this recommendation “is not supported by research and breastfeeding can continue as normal.” The FDA’s own prescribing information for Plan B One-Step notes that small amounts of progestin pass into breast milk but does not specify any required waiting period.
A pharmacologic study of 12 breastfeeding mothers who took the standard 1.5 mg dose of levonorgestrel found that the estimated infant exposure was just 1.6 micrograms on the day of treatment. For context, that is a trace amount, far below any level associated with harmful effects. No adverse outcomes in infants have been reported in the clinical literature from this exposure.
Effects on Milk Supply
A single dose of Plan B does not appear to reduce milk supply. A CDC safety review found that breastfeeding outcomes did not differ between women who took levonorgestrel emergency contraception and those who did not. The FDA label does mention isolated post-marketing reports of decreased milk production with progestin-only pills, but those reports relate to daily, long-term progestin use rather than a one-time emergency dose. The NHS Specialist Pharmacy Service similarly confirms that no changes in milk supply have been reported following emergency contraception use.
No Need to Pump and Dump
Pumping and discarding your milk after taking Plan B is not medically necessary. Because the drug passes into milk in such small quantities, there is no clinical reason to discard any expressed milk. If you’ve already pumped and dumped out of caution, that milk loss won’t affect your supply long-term, but you don’t need to continue doing so.
Why Plan B Is Preferred Over Other Options While Breastfeeding
If you’re breastfeeding and need emergency contraception, levonorgestrel (Plan B) is generally considered the best hormonal option. The Academy of Breastfeeding Medicine recommends it over combined estrogen-containing emergency contraceptives because estrogen can suppress milk production. Plan B also tends to cause less nausea, which matters when you’re caring for an infant.
There is another type of emergency contraceptive pill called ella (ulipristal acetate). Older guidance recommended discarding breast milk for up to a week after taking ella, but the Faculty of Sexual and Reproductive Healthcare has since reversed that position, stating that no interruption of breastfeeding is necessary after a single dose of ulipristal acetate either. The risk of infant side effects from ella is considered extremely low given its low toxicity profile. Still, if you have a choice between the two and are breastfeeding, Plan B remains the more commonly recommended first option.
Timing and Effectiveness
Plan B works best when taken within 72 hours of unprotected sex, though it retains some effectiveness up to 120 hours (5 days). Its effectiveness decreases with each passing day, so taking it sooner matters more than timing it around a feeding schedule. If you’re delaying the pill to create a gap before your next breastfeeding session, that delay could reduce the contraceptive benefit without providing any meaningful safety advantage for your baby.
The bottom line: take Plan B when you need it and continue breastfeeding on your normal schedule.