When is it better to start using hormones in myotonic dystrophy? Infancy and early childhood usually have no clinical symptoms, and if they do, they are mild. The side effects of hormone use during this period outweigh the efficacy, so it is not recommended for children under 2 years of age and during the period of motor function development (3 to 5 years). The most reasonable time to start hormone therapy should be placed in the period when motor development has stopped after reaching its peak or when motor function begins to decline. It is easier to judge the efficacy of hormone therapy at this time, as both the improvement of self-conscious symptoms and the change of clinical signs can be visually observed, which helps doctors to make trade-offs between efficacy and side effects. In any case, when starting hormone therapy, the patient’s motor function status and the risk of side effects from hormone therapy should be carefully considered before making a decision. After hormone therapy is started, attenuated vaccines (live vaccines) are sometimes prohibited depending on the amount of hormone used. Therefore, it is best to complete the necessary live vaccinations before starting hormone therapy.