The claim is that homeopathic medication contains zero active ingredient, and so it can't harm you.
But just about anyone can set up a factory making this stuff, and there's not much regulation, which means we have no idea what's really in there.
Homeopathic teething gels are linked to possibly 10 deaths, and 400 children harmed. That's after the manufacturers were warned about incorrect dilution.
> Last month, the Food and Drug Administration warned parents to stop using homeopathic teething gels and tablets, which may have been improperly diluted. Yesterday the agency said it is investigating 10 infant deaths and more than 400 reports of seizures, fever, and vomiting that may be connected to the use of the teething treatments in the past six years.
It's a really pernicious myth that homeopathy can't do anything harmful. Skeptics love to talk about the extremely high dilutions because it makes a story that suits their purposes well. But doing so is a bit dishonest; homeopathy generally doesn't use extremely high dilutions, but it doesn't always use extremely high dilutions. Nor are production standards particularly well regulated or enforced in many countries.
As a couple others just pointed out, homeopathic teething drops in particular have come under recent scrutiny in the US for having dangerous concentrations of belladonna.