If i had hereditary fructose intolerance how much fructose would i need to consume to cause sudden hypoglycemia. would a very small amount cause sympt?

Rare: If you are 35 and carry this diagnosis I would only guess that you probably can tolerate small amounts of natural fructose and you should know that amount by now. If this is only a possibility would recommend abstaining from concentrated sugar foods, given your history of hypoglycemia. Talk to your doctor before challenging yourself with large amounts of sugar containing products.