Clenbuterol Products | Cleanchem - Clenbuterol is a beta-2 adrenergic agonist used as a bronchodilator in some countries for treating asthma, though it is not approved for human use in many regions. It is more commonly used in veterinary medicine and as a performance-enhancing drug. Clenbuterol increases muscle mass and reduces fat, making it popular in bodybuilding. Side effects include tremors, tachycardia, and anxiety.