I had come across a post on another board about a horrible happening to a baby due to unregulated amounts of belladonna in the tablets. I don't know if it's against the rules to post a quote from another board so unless told otherwise I won't do that. But if you want to pm me I can give you a link.
There is no belladonna in homeopathic tablets. There is no ANYTHING measurable in them. That's the whole point of homeopathy, and the reason that skeptics are, well, skeptics. You can "prove" a remedy (DS got ahold of the chamomile pellet tube and for over a year it didn't work on him, it caused him to get hyper instead of calm) but it's not going to poison you.
So OP, I take it you're talking about Hyland's? They worked for DS about half the time I used them. The other half, it just wasn't right for that moment of teething. So I would look at what his current symptoms were, consult my homeopathy books, and find a SINGLE remedy for him. When I did that and when I actually had what he needed, it always worked. Even if that single remedy was in the "shotgun" approach of the Hyland's.
Homeopathy is miraculous, weird, difficult to understand, and a bit wild. But it's also terrific and wonderful! It works on babies and animals (even PetSmart recommends Rescue Remedy to put into the water of skittish animals for fireworks days) so it's not mind over matter...it's just a really cool way of helping people.
And if you ask me about arnica, I could talk all day, that stuff has saved us more than once. Especially me and DS, b/c we are prone to nasty bone-deep leg aches (they were so bad when I was a child that I was tested for juvenile RA just to get an explanation), and the arnica cream (from Salmon Creek Therapeutics) and pellets for pains you can take care of from the outside have changed my life, and have made DS's life much better.