Tremor, nervousness, tachycardia, dizziness, headache, hypokalemia, dry mouth, throat irritation, urinary retention, nausea and arrhythmia may occur. Allergic-type and anaphylactic reactions have been reported in some cases. As with other bronchodilators, in some cases cough, and in very rare instances, paradoxical bronchoconstriction have been observed.