This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Asthma, Subject name: Pharmacology
Commonest side effect of short acting beta 2 agonist used in asthma is- 
Select and explain. 
A. Muscle tremors, B. Hypokalemia, C. Hypoglycemic attacks, D. Sedation
A: Muscle tremors
Answer: A: Muscle tremors 
Explanation: Ans. is 'a' i.e., Muscle tremors Short acting beta 2 agonists in asthma* Beta agonists are by for the most effective bronchodilators, and are well tolerated when given by inhalation.* They work as functional antagonists on the airway smooth muscles and therefore prevent and reverse bronchoconstriction, irrespective of the mechanism.* They inhibit mast cell release and are therefore used in exercise and allergen induced asthma.* They are inadequate to suppress chronic airway inflammation, and do not reduce airway hyperresponsiveness, and are therefore not adequate alone to treat persistent asthma.* Side effects are not usually a problem when beta 2 agonists are administered by inhalation, but become more frequent with oral and intravenous administrations. The commonest adverse effects are muscle tremors and palpitations which are more common in elderly patients.