Hi and welcome!
Hemangioma is a term that refers to a birthmark that only babies have. They resolve in some way or other by puberty.
If you have a vascular birthmark as an adult, it is either a port wine stain or vascular malformation, but not hemangioma.
Many doctors still use the terms interchangeably, but they are not the same thing.
That medication would not work for a vascular malformation, though it does work in some children for hemangioma. There is no evidence that it would work for you, though, and I don't think any physician would prescribe it.
Where are you located? Perhaps you could see a specialist that does have experience with vascular malformations in adults.