I think that a better questin might be low little can you take and still get a great effect. I wouldn't suggest usig more than 8-10 Iu split through the day. I've gone as high as 20iu in a day for a short time. Mainly I got bad side effects in the joints. I suggest breaking your dose up iinto around 3 or 4 shots s day. Your body is only going to use so mcuch for muscle growth at once. so spread it out through a day and try to keep levels always elevated