The treatment of chronic obstructive lung disease is multifaceted. If the patient smokes, he or she must quit. Treatment includes bronchodilator therapy, glucocorticosteroids, antibiotics for acute exacerbations, oxygen therapy for patients with chronic hypoxemia (it can also help patients with nocturnal and exercise-induced hypoxemia), and respiratory rehabilitation for motivated patients. Inhaled β-agonists and anticholinergic agents have additive effects in recommended doses, as do theophylline and β-agonists.