The perception loss is not permanent. It will come back in time (usually as you travel from one area to another)but you might want to keep the stimpacks handy instead and only go for powder as a last resort. Usually I just sell/gamble them away for better stuff, but you usually can loot so much of it, even later in the game. It always seems like one or more characters have some bags on them during a mission.
my advice is if you have them, use them, but when you get back to the bunker barter them for the good stuff like stims and medi-kits.