Sue Fortune, from Penycae, near Wrexham, was unhappy when questions were raised over her receiving the unlicensed drug Ovestin (oestriol).
But Mrs Fortune argued she had been using Ovestin for five years and "it's been enormously helpful".
The board told her Ovestin cost them over pounds 200 per month to supply.
Rhosllannerchrugog GP Peter Saul said: "Ovestin isn't a standard treatment for MS in women but there is some evidence that it seems to help some patients.
"Ovestin is not licensed anywhere for use for treating patients with MS and is extremely difficult to obtain in the UK.