Yes, opioids can be passed in breast milk but at very low levels. In fact, many medications are delivered at low levels through breast milk and are still considered “safe” during breastfeeding.
Buprenorphine is a “category C'' medication in pregnancy, which means that the benefits may outweigh the risks of using buprenorphine while pregnant or breastfeeding. Buprenorphine is actually delivered at lower levels to the fetus through breast milk than in-utero.
It is definitely safe to breastfeed while on Suboxone for any mother that was already on Suboxone during their pregnancy. If you are on Suboxone and plan to breastfeed, talk to your doctor for more information.