FDA has approved deflazacort (Emflaza—Marathon Pharmaceuticals) tablets and oral suspension for the treatment of individuals aged 5 years and older with Duchenne muscular dystrophy (DMD). This is the first FDA approval of any corticosteroid to treat DMD and the first approval of deflazacort for any use in the United States. The drug's efficacy was demonstrated in a clinical study involving nearly 200 males aged 5–15 years with documented mutation of the dystrophin gene and onset of weakness before aged 5 years. After 12 weeks, patients taking deflazacort saw improvements in a clinical assessment of muscle strength across several muscles compared with those taking a placebo. In addition, those in the treatment group maintained an overall stability in average muscle strength through the end of the study at week 52. Adverse events caused by deflazacort are similar to those experienced with other corticosteroids, with the most common including facial puffiness, weight gain, increased appetite, upper respiratory tract infection, and extraordinary daytime urinary frequency. Less common adverse events include problems with endocrine function, increased susceptibility to infection, elevation in blood pressure, risk of gastrointestinal perforation, serious skin rashes, behavioral and mood changes, decrease in the density of the bones, and vision problems such as cataracts. Patients taking immunosuppressive doses of corticosteroids should not receive live or live attenuated vaccines.