Hello and welcome...I believe that one pill can cause withdrawals as your brain is used to having that "crutch" and artificial endorphins if you will. It is different for everyone, but most of the time when you give your brain something, it gets used to it, and when you remove it, it screams out for what it is missing. When people taper, even slowly from their pain meds and get down to 1 pill a day or a half a pill a day, their bodies adjust to the lowering of the pill, and when it is taken away completely, they still go through some sort of withdrawal, so I would imagine it would be the same with your situation because your body is used to it. Your age, health and duration of use also play a part in it. I came off a 8 day 10/325 norco regiment for pain, cold turkey, and it wasn't really that bad. My energy returned after about a week and full blown at about 2 weeks. I took them for 10 years. Others at the dose I was at took months or a year or more to feel "normal" (if there is such a thing). I thought the weird headed feeling would never go away, and it was my brain adjusting to not having the pills anymore. But it does go away, and it will be better! You just have to power through it. Do some walking or light exercise to kick in your natural endorphins. That works wonders!