Are sulfur ointments bad for babies' skin in treating insect bites?

It depends on the intensity of the sulphur's content in the ointment. If you use an ointment specifically made for baby's skin (usually 5%-10%), it will not be dangerous. In fact, it is one of the most safest options that doctors will prescribe for babies and pregnant women. My friend mixes a tiny bit of Scabisil sulphur ointment with baby lotion for her baby's insect bites and scabies.