This multi-centre, randomised, double-blind, placebo-controlled crossover trial will compare changes in strength-related motor function following treatment with creatine monohydrate to treatment with placebo, as measured by the Motor Function Measure, from baseline to 12 weeks. Eligible subjects will undergo baseline assessments then will be randomised to either creatine monohydrate therapy or placebo for three months, followed by a six week wash-out period, then crossover to a further three months of therapy with either placebo or creatine. Subjects will undergo clinical assessments and study safety assessments at the beginning and end of each treatment period. The study will begin recruitment in early 2017.

Inclusion Criteria:

• Is between the ages of 5 and 18 years inclusive at the time of randomisation;
• Has a confirmed genetic diagnosis of Facioscapulohumeral Muscular Dystrophy (FSHD) types 1 or 2;
• Has a legally acceptable representative capable of understanding the informed consent document and providing consent on the participant's behalf.

Exclusion Criteria:

• Has clinically significant elevation in plasma creatinine level or unexplained hypertension at screening;
• Has a prior diagnosis of chronic renal failure;
• Has a known hypersensitivity to creatine monohydrate of maltodextrin placebo;
• Patients already taking any medications to increase muscle bulk or strength or concomitant use of regular sodium valproate, corticosteroids of alpha agonists such as salbutamol.