Hi, I took it for just a few days and didn't seem to do much for the EM; I think it just made my feet colder between flares.
Here http://www.ncbi.nlm.nih.gov/pubmed/11050591 it says:
"Different subtypes of erythromelalgia?
Belchhas categorized 3 subtypes: thrombocytosis/
hyperviscosity, microvascular ischemia (vasoconstrictive),
and vasodilatory. Whereas most patients
exhibit the vasoconstrictive/reactive-hyperemia type
that responds to the infusion or invasive approaches
mentioned above, the less common vasodilatory type
will worsen with these therapies. Conversely, the latter
may respond to the vasoconstriction of unselective
beta blockers like propranolol, whereas the former
will worsen with such treatment. To differentiate
these types, Belch recommends vascular studies performed
in warm and cool environments that include
Doppler pressures, laser Doppler flowmetry, thermography,
and tissue PO2 monitoring. The Mayo
Clinic often performs nerve biopsies."