After seeing multiple doctors in the USA (where I no longer live thankfully) for a chronic mouth ulcer problem an allergist prescribed me colchicine which seemed to cure them. These ulcers lasted over 15 years and colchicine seemed to be the only thing to eradicate them.
Insurance wouldn’t cover the cost and colchicine cost me $500 a month for a bottle. In the UK I can pay 10 pounds. Crazy drug and crazy price for something 3000 years old