"i have had 2 left knee reconstructions and was prescribed vicodin 10/325. after a few short weeks i was already immune to the dosage and had to start taking more. although it works great for body pain, i have a killer headache and no appetite once it wears off. when i have a few good days that are pain free and i don&#039;t use the medication i feel like i&#039;m going through withdrawls."