Asmanex is a corticosteroid most commonly used to control and counteract symptoms of asthma, such as wheezing and shortness of breath. Asmanex is typically regularly used and is not recommended for relief of sudden asthma attacks, and is not considered a rescue inhaler. Asmanex is administered in the form of an inhaler and works by decreasing swelling and irritation in the airways to inhibit inflammation. Asmanex requires a prescription and may be prescribed for other uses. Be sure to ask your doctor or pharmacist for more information.