Safety

Can I use emergency contraceptive pills if I am breastfeeding?

Yes, using progestin-only emergency
contraceptive pills (like Plan B One-Step, Next Choice One Dose, My Way and Levonorgestrel Tablets) once will probably
not affect either the quantity or quality of the milk your breasts
are producing. Although some hormones may be passed on through a mother’s
breast milk, your child is not likely to experience any adverse effects
from it. However, the label for ella (ulipristal acetate) states that nursing mothers should not use ella, because it is unknown whether there could be risk to the child. European recommendations for ellaOne (the same product as ella) says that breastfeeding women can use it but should pump and discard the milk for a week.

If you are breastfeeding regularly, you might not need to use emergency
contraceptive pills if you had sex under circumstances
that would otherwise put you at risk for getting pregnant. That’s
because in the first 6 months after having a baby, a woman who is
feeding her child only breast milk and who has not had her period
since giving birth is not likely to be ovulating, meaning that your
ovaries are probably not releasing eggs that could be fertilized and
cause a pregnancy. But be careful about relying on this possibility
if you need or want to prevent pregnancy: even if you are breastfeeding,
you could still be at risk for pregnancy if you are also feeding your
baby formula, pumped milk, or other food, your baby is more than 6 months old, or
you have had your period since your baby was born.

A thorough and up-to-date academic review of the medical and social
science literature on emergency contraception is available; click
here for the PDF .