Side effects are the most frequent reason for discontinuing treatment with Calcitonin. Having been assessed in a previous report that the intranasal administration of Synthetic Salmon Calcitonin (SSCT) is as effective as its intramuscular administration, the aim of this work was to investigate the side-effects of intranasal administration of SSCT in patients who are known to show intolerance after intramuscular administration of the drug. The results show that intranasal administration of SSCT does not give rise to side-effects even in patients known to be intolerant to SSCT by the intramuscular route.