(1) Asthma is influenced by a variety of factors and its natural history varies over time. Clinically, asthma ranges from fleeting respiratory discomfort to incapacitating dyspnoea due to frequent and severe attacks. (2) This article examines the general principles of long-term drug therapy for asthma patients, taking into account the results of the clinical drug evaluation described in part I of this review (French edition). (3) The four most recent clinical practice guidelines did not take into account the latest data on the potentially severe adverse effects of long-acting beta-2 agonists. At least two of these guidelines received financial support from drug companies. (4) There is a general consensus that intermittent asthma does not require continuous therapy. For these patients, drug treatment is based on short-acting beta-2 agonists taken solely when symptoms arise. (5) Long-term treatment of persistent asthma is based on inhaled steroids at doses adapted to severity. However, given the adverse effects of inhaled steroids, the minimal effective dose should be identified and treatment should be reduced in a stepwise manner once asthma is under control. (6) When severe asthma persists or does not improve with high-dose inhaled steroid therapy, the treatment with the best risk-benefit balance is oral steroid therapy. (7) The use of long-acting beta-2 agonists is limited to the control of nocturnal symptoms when inhaled steroid therapy is inadequate. (8) Standard drugs used for asthma have no proven foetotoxicity, whereas poorly controlled asthma carries a risk of complications for both the mother and her unborn child.