Studies show that there are few (if any) side effects from taking creatine. One study examining effects of creatine on blood pressure, renal function, and plasma creatine kinase showed no ill effects after 5 days of 20g/day.
Another study saw some patients complain of "side effects such as dizziness, headache, tachycardia, heart skipping or palpitations, shortness of breath, nervousness, and blurred vision." However, the number of reports was comparable to those received from patients taking the placebo.
