V. Treatment
The most effective treatment for asthma is identifying triggers, such as pets or aspirin, and limiting or eliminating exposure to them. Desensitization is commonly attempted, but has not been shown to be effective. As is common with other respiratory diseases, smoking or second-hand smoking adversely affects asthmatics in several ways, including an increased severity of symptoms, a more rapid decline of lung function, and decreased response to preventive medications, resulting in more emergency room visits, and more asthma-related hospital admissions. Smoking cessation and avoidance of those who smoke is strongly encouraged in asthmatics.
The specific medical treatment recommended to patients with asthma depends on the severity of their illness and the frequency of their symptoms. Specific treatments for asthma are broadly classified as relievers, preventers and emergency treatment.
Relievers: bronchodilators are recommended for short-term relief in all patients. For those who experience occasional attacks, no other medication is needed.
Preventers: anti-inflammatories. For those with mild persistent disease (more than two attacks a week), low-dose inhaled glucocorticoids—or alternatively, an oral leukotriene modifier, a mast-cell stabilizer, or theophylline—may be administered. For those who suffer daily attacks, a higher dose of glucocorticoid in conjunction with a long-acting bronchodilatator may be prescribed. In severe asthmatics, oral glucocorticoids may be added to these treatments during severe attacks.
Emergency treatment: When an asthma attack is unresponsive to a patient's usual medication, other treatments are available to the physician or the hospital: oxygene, nebulized, inhaled or injected long or short-term bronchodilatator and in case of extreme urgency intubation and mechanical ventilation.
For those in whom exercise can trigger an asthma attack, higher levels of ventilation and cold, dry air tend to exacerbate attacks. For this reason, activities in which a patient breathes large amounts of cold air, such as cross-country skiing, tend to be worse for asthmatics, whereas swimming in an indoor, heated pool, with warm, humid air, is less likely to provoke a response.
Symptomatic control of episodes of wheezing and shortness of breath is generally achieved with fast-acting bronchodilators. These are typically provided in pocket-sized, metered-dose inhalers (MDIs). In young sufferers, who may have difficulty with the coordination necessary to use inhalers, or those with a poor ability to hold their breath for 10 seconds after inhaler use (generally the elderly), an asthma spacer is used. The spacer is a plastic cylinder that mixes the medication with air in a simple tube, making it easier for patients to receive a full dose of the drug and allows for the active agent to be dispersed into smaller, more fully inhaled bits. 
A nebulizer—which provides a larger, continuous dose—can also be used. Nebulizers work by vaporizing a dose of medication in a saline solution into a steady stream of foggy vapor, which the patient inhales continuously until the full dosage is administered. Nebulizers may be helpful to some patients experiencing a severe attack. Such patients may not be able to inhale deeply, so regular inhalers may not deliver medication deeply into the lungs, even on repeated attempts. Since a nebulizer delivers the medication continuously, it is thought that the first few inhalations may relax the airways enough to allow the following inhalations to draw in more medication.
Relievers include:
- Short-acting, selective ß2-adrenoceptor agonists (salbutamol, fenoterol, reproterol). Tremors, the major side effect, have been greatly reduced by inhaled delivery, which allows the drug to target the lungs specifically; oral and injected medications are delivered throughout the body. Patients must be cautioned against using these medicines too frequently, as with such use their efficacy may decline, resulting in an exacerbation of symptoms which may lead to refractory asthma and death.
Older, less selective adrenergic agonists, such as epinephrine — which, unlike other medications, are available over the counter in the US under the Primatene brand. Cardiac side effects, although uncommon, occur more often with the less selective drugs. They also provide a shorter period of relief than the selective bronchodilators. In emergencies, these drugs were sometimes administered by injection but their use in this situation has declined.
Anticholinergic medications, such as ipratropium bromide may be used instead. They have no cardiac side effects and thus can be used in patients with heart disease; however, they take up to an hour to achieve their full effect and are not as effective as the ß2-adrenoreceptor agonists.
