I started taking some this week, and had ill effects. For anyone starting out, I recommend starting with small amounts and building up.

The packaging of my product recommended 4-6 grams four times a day for the loading phase. I did two 4 gram doses and had a massive headache that night and the next morning. A day or two later, my thighs felt like I had spent hours doing squats with heavy weights.

It's important to make sure to drink extra water, and electrolytes, when supplementing with creatine.