Is wart remover (40% salicylic acid pad) safe while breastfeeding? any side effects for baby?

Topical tx is safe: This should be safe since it is a topical treatment. Just curious where are you using this? If not on the breast near the nipples I do not see an issue

Pads are safe to use: while breast feeding, unless, of course, the wart is on your breast, and I would not recommend using the acid for warts there anyway. Salicylic acid pads are most effective where the skin is somewhat thickened, such as the sole of the foot. The acid works locally and is not significantly absorbed.

General rule BF: Topical agents you use on skin will not have meds absorbed into the blood that could enter the BM. As long as the agent (including wart med) is not used on the breast where the kid would have contact, it is fine to use while BF.