Well if it were me, I wouldn't put anything on a baby's butt that contained boric acid. It is very toxic and has been known to cause death in infants, particularly if the skin is abraded. As far as I know, it's use has been discontinued in baby ointments in Canada. It does do a good job killing roaches though, if you can hold the buggers still long enough to smear their little bottoms.

I am usually a fan of old remedies. When one of my daughters was small, our doctor gave us a prescription for an expensive steroidal cream for a persistant sore on her arm, that looked a bit like ringworm but wasn't.

We went through a tube of the stuff and it still hadn't cleared up. A while later, I was digging around in the medicine chest and found an ancient tin of Watkin's petro-carbo salve. A couple of dabs and the sore cleared it up immediately.

I figured it worked so well, I tracked down a new tin of the ointment and carefully read the label to compare it to the old tin. Even though it still retained the same name, the new stuff no longer contained carbolic acid and wasn't particularly effective for anything.

I sitll use a large tube of Hibitane horse ointment for first aid for us and the animals. It was cheap, effective, used in hospitals and I believe widely available for human use in the UK and Oz, but you can't get it easily in Canada any longer, even for horses. It's probably been found to be as risky as ointment containing boric acid.