Is it safe to use creatine?

Probably: Creatine is moderation is probably safe. High doses may be harmful to your kidneys. Be sure to stay very well hydrated.

Creatine.: Creatine in doses of 1000 to 5000mg daily has been shown to increase muscle mass, muscle size and muscle energy stores. Creatine must be taken with lots of water throughout the day, and doses must not exceed 5000mg daily to avoid impairment of kidney function. The dose can be taken all at once, preferably after exercise to facilitate ATP store replenishment in the muscles after exercise.