<p>Care should be taken with patients suffering from myocardial insufficiency or thyrotoxicosis. Due to the hyperglycaemic effects of &beta;2-stimulants, additional blood glucose measurements are initially recommended when Terbutaline therapy is commenced in diabetic patients. If a previously effective dosage regimen no longer gives the same symptomatic relief the patient should seek further medical advice, for reassessment of asthma therapy, as soon as possible. Potentially serious hypokalaemia may result from &beta;2-agonist therapy. Particular caution is advised in severe asthma as this effect may be potentiated by concomitant treatment with xanthine derivatives, steroids, diuretics and by hypoxia. It is recommended that serum potassium levels are monitored in such situations. Due to the positive inotropic effect of &beta;2-agonists, these drugs should not be used in patients with hypertophic cardiomyopathy.</p>