I need to know about drug treatment for Hypothyroidism.?

Hi. My brother is a Down Syndrome child and has been found to have Hypothyroidism. He is 14 years old. The doctor has suggested thyroxin for his treatment, saying that she will be starting the trial with a very small dose. I would like to know (particularly from someone who has undergone this treatment) about any side effects and their implications. I would also like to know how long the therapy is carried out for and what are the visible advantages. Thanks.

: http://alcoholdrugstreatment.info/i-need-to-know-about-drug-treatment-for-hypothyroidism