Losing health in base due to undo button

when i recall, i usually instantly buy an item. I am usually missing health when i recall and buy an item. Sometimes, i decided i no longer want the item, and i click the undo button. i instantly go back to the health i was at when i bought the item. It wastes a lot of time because i have to get back up to full health again before i get back into the game. I once almost died because of this because a karthus ult happened when i was in base, and i clicked the undo button because i wanted to buy a different item, and his ult put me somewhere around 30 health. Thats when i really noticed the problem of the undo button in the base. im not asking it to be removed beause it saves me a ton of gold, but i dont want to lose a thousand health because of it either.