<p>The frequency of side-effects is low at the recommended doses. Side-effects which have been recorded such as tremor, headache, tonic cramp and palpitations are all characteristic of sympathomimetic amines. A few patients feel tense; this is also due to the effects on skeletal muscle and not to direct CNS stimulation. Whenever these side-effects have occurred the majority have usually been spontaneously reversible within the first week of treatment. Urticaria and exanthema may occur. In children sleep disturbances and disturbances of behavioural effects have been observed. Potentially serious hypokalaemia may result from &beta;2-agonist therapy.</p>