Non-systematized chronic musculoskeletal pains are a frequent reason for consulting in general practice. The possible causes are numerous and sometimes nonspecific. In some cases, the etiologic investigation of patients with non-systematized and chronic musculoskeletal pain can not highlight any organic cause. Several studies have shown a link between these symptoms and vitamin D deficiency, characterized by a blood level of 25 (OH) vitamin D < 20.8ng/ml. This deficit is easy to identify and to correct through proper vitamin D supplementation with few side effects. Nevertheless, it remains unknown and vitamin D deficiency is rarely considered as a possible etiology in patients with chronic pain. We hypothesize that vitamin D supplementation in patients with non-systematized musculoskeletal pain and deficient in vitamin D could improve painful symptoms. We aim to perform a double-blind randomized controlled trial, vitamin D versus placebo, to assess the pain improvement after vitamin D supplementation.

Inclusion Criteria:

• Women and men
• Aged 18-50 years (included)
• Consulting their general practitioner
• With chronic and diffuse musculoskeletal pain, without known etiology, lasting for at least 3 months
• With a 25(OH)vitamin D deficiency <20.8 ng/ml (52 nmol/l) at inclusion
• Who signed the consent form

Exclusion Criteria:

• Identifiable source of pain requiring an appropriate specific management
• Disease or treatment that may interfere with the metabolism of vitamin D
• Current or previous hypercalcemia or hypercalciuria, treatment with digitalics and patients with history of nephrolithiasis
• Current treatment with vitamin D or at least one vitamin D vial taken over the previous 6 months
• Pregnancy or breastfeeding
• not affiliated to a social security system
• Refusal or inability to give consent