Beta agonists, also known as beta adrenergic agonists, are medications given for dilating the bronchi (See: Bronchi) in the lungs. These are done to open the airways and relax the muscles around the airways when they tighten during an asthma attack. These drugs are also given for COPD (chronic obstructive pulmonary disease) patients. These drugs have the opposite function of beta blockers (See: Beta blockers). They act by mimicking the actions of norepinephrine and ephedrine. These medicines come in the form of inhalers and oral medicines. These medicines activate the beta-2 receptors of the muscles in the airways. By activating the beta-2 receptors, the muscles around the airways relax thereby dilating them. This leads to better breathing and alleviation of the symptoms of shortness of breath. Beta agonists are fast acting drugs and their action lasts for a few hours. Beta agonists are also used for bradycardia (See: Bradycardia), beta blocker poisoning, hyperkalemia (See: Hyperkalemia), and heart failure. Beta agonists are of two types – short-acting beta agonists, and long-acting beta agonists. Side effects of beta agonists include hypertension, anxiety, insomnia, tachycardia (See: Tachycardia), headaches, and hypoglycemia. Beta agonists have adverse effects on diabetic patients as they tend to increase insulin and glucagon secretion along with effects on liver causing hypoglycemia.