High concentrations of fluoride, sure. It’ll upset your stomach. Can even be toxic if you drink too much, but we’re talking over 10mg a day, when most of the time 1L of water has 0.7mg of fluoride. So unless you’re drinking over 14 liters of water a day, you’ll be just fine. And if you’re drinking that much water, you’re already at risk of water intoxication which is more concerning.

But in order to actually cause real harm you’re going to need to be eating large amounts of toothpaste and such.

Edit: To put this into perspective. Vitamin A, an essential vitamin humans require, which we literally go blind without (among other things) can be toxic when you take more than 3mg of it a day. That’s less than a third of fluoride. Just because something can become toxic in higher doses doesn’t mean it’s toxic when used properly.