How old is this person and when did they start fainting? Neurocardiogenic syncope is exceedingly common amongst teenagers - most pediatric cardiologists will say between 20-25% of adolescent females and 5-10% of adolescent males, will have issues with it. The good news is that it's typically outgrown by the early 20's, and even before then, aggressive hydration and a little extra salt in the diet is usually enough to cause a massive improvement in symptoms (I've had patients who have fainted >10x a day that subsequently went months without a spell after increasing their fluids - still with occasional lightheadedness with orthostatic changes but practically a different person). There are other medication options possible as well, but most cases respond with hydration.
Now if this is some non-trad 38 year old with neurocardiogenic syncope that started a couple years ago, it's a very different story. That certainly would be more troublesome as a limiting factor on their effectiveness.