I didn't actually do this research but this is some medical information about creatine.
Creatine phosphate is naturally occurring and produced in the liver, pancreas, and kidneys, and your creatine stores are broken down into "creatinine" at around a rate of 2g/day and excreted by the kidneys. Basically when you use your muscles, energy (in the form of ATP (adenosine triphosphate - meaning three phosphates) needs to be continually renewed). This is accomplished by combining creatine phosphate with the readily available ADP (adenosine diphosphate - same thing but with only two phosphate groups and needs the third to be used as energy). In muscle cells, creatine is available at three times the concentration of ATP, so it is readily available to bind with ADP. This process is so efficient that when you're resting your muscles, your depleted reserves of creatine phosphate are easily restored by breaking down the ATP into ADP+P (P is the phopshate from the creatine phosphate).
The highest external sources of creatine phosphate (sometimes called phosphocreatine) are in herring, salmon, tuna, pork, and beef, although cooking apparently degrades the creatine concentration (so keep eating your sushi).
From what I can tell, most studies suggest that negative side effects of taking creatine are minimal, with the most common being diarrhea, probably as a result of the high osmotic load placed on the digestive system (i.e., due to the increased water you are supposed to be drinking, flowing in and out of cells in the digestive tract). Some rat studies suggest long term use can cause renal failure (kidneys), but since creatine as a nutritional supplement has only been around since 1992, long term studies in humans are lacking. If you have ever had kidney stones, or any history of kidney malfunction in any of your relatives, I would highly caution against creatine supplementation.
Some studies also suggest that most athletes are taking more creatine than necessary (i.e., apparently only a mere 2 grams per day is sufficient). From what I can tell, the loading phase (20 g for the first 5 days) is also completely unnecessary, as after about four weeks, it makes no difference at all whether you had loaded in the beginning or not in terms of performance enhancement (only makes a difference in the first couple weeks). As for "dosage-cycling" or whatever you call it, I would recommend doing this, as it has been proven in the rat model that chronic creatine ingestion "down-regulates" the production of creatine in skeletal muscles (again, no human research, but I trust it anyhow).
My biggest and most strictest advice would be to absolutely ensure you are not cheaping out on this product as it is NOT at all regulated or assessed by ANY federal governing bodies (e.g., Food and Drug Adminstration in the US, Health Canada in this country). I would definitely look for 100% pharmaceutical grade creatine phosphate, and only made in Canada, the US, or maybe Germany. Definitely NOT CHINA. I don't know if you can get the brand InterACTIVE, but I looked into that one and feel okay about it. It's at least registered with Health Canada and has been assessed by Quality Alliance International. (
http://www.interactivenutrition.com/products/creatine.php).
So in summary... I would basically not take any more than 2-3 grams per day, before your workout, with some simple non-citrus carbohydrate liquid like your white grape juice or even gatorade or something. Apparently you shouldn't take it with a large meal as high amounts of fibre can inhibit your body's absorption of creatine.
