I received a warning about comfrey. There are toxicity issues with it for people and animals if ingested. Banned in this country as a dietary supplement. Salves “seem” to be ok - it’s used a lot for that, but some say ‘no’ even to that because the toxin can absorb through the skin. I need to do some more research before I go there.
What I’m really getting ‘put off’ by is the invasiveness of the plant & evidently, they’re large plants as well. I’m still having nightmares from out-of-control catnip I had some years back. The cats were happy (they really loved crushed leaves in a sock with a knot in it to keep them from eating the stuff), but it took over a large portion of a garden area.
I planted Chocolate Mint in a raised bed back in the day. BIG Rookie Mistake!
Before I sold that house, I nuked it. ;)
There is a lot of debate over whether the studies showing toxicity were accurate. The toxin is so mild and at such a low concentration, you’d pretty much have to eat comfrey-leaf salads every day for several years before showing any ill effects. But, if you really aren’t comfortable with it, you can use oysterleaf instead. It contains the same healing compound, allantoin, but at a much lower concentration, and without the toxic alkaloids.
Personally, I think you’d absorb more toxins standing in a paved parking lot for 5 minutes. But as I said, it’s a matter of some debate.