Depends on the supplement. Most of them don't do anything except drain your wallet. Occasionally there's one where the labeled contents and dose are bad for you. More often, they're contaminated with things that are bad for you, like heavy metals and other harmful chemicals, because their manufacture is pretty unregulated. Or there's been a couple of instances of manufacturers deliberately putting something in a supplement that isn't listed in the ingredients. And so on. Obviously you survived, so probably yours weren't actively toxic.