Exactly what you would expect from Clen. It slightly elevates body temp and heart rate. Make sure to keep your electrolytes up to avoid cramping. I have also heard that body temperature increase is an indication that B2 receptors have not been fully downregulated. Once body temp is no longer elevated B2 receptors have been downregulated and a period off is required. There is a good article about Clenbuterol in the new issue of Muscular Development. Anyways I loved clen, worked miracles. Best of luck.