What is the appropriate dosage and duration of vitamin D supplementation for patients diagnosed with deficiency?

Dosage and Duration of Vitamin D Supplementation for Deficiency

For adults diagnosed with vitamin D deficiency, a rapid correction regimen involves a fixed loading dose totaling approximately 300,000 international units (IU) of vitamin D3, administered either as separate weekly or daily doses over 6–10 weeks. This loading phase should be followed by maintenance therapy starting one month after loading, with a daily dose of 800–2000 IU vitamin D3, up to a maximum of 4000 IU daily in certain conditions such as malabsorption under specialist advice.

For children aged 1 month to 18 years with vitamin D deficiency, if rapid correction is needed (e.g., symptomatic cases), prescribe a fixed loading dose for 8–12 weeks followed by regular maintenance vitamin D therapy starting one month after loading. Maintenance supplementation for children is typically 400–600 IU daily.

Vitamin D3 (cholecalciferol) is the preparation of choice for treatment, with vitamin D2 as an alternative in some clinical situations. Intramuscular vitamin D is not recommended first line due to unpredictable bioavailability and slower onset.

Maintenance therapy should continue long-term unless there is a significant lifestyle change improving vitamin D status.