What should you know about chronic vitamin D deficiency?

Vitamin D helps the body handle calcium and support bone and muscle function. Ongoing deficiency may be associated with generalised weakness, bone or joint pain, low mood, or fatigue, although these symptoms have many possible causes. Some people have no clear symptoms.

Risk can be influenced by limited sunlight exposure, reduced absorption, certain medicines and other health conditions. Obesity (/conditions/obesity/) may alter vitamin D availability. A blood test and review of bone health help clarify the situation.

Arrange a clinical review rather than taking large doses on your own. Your clinician can confirm the level, look for contributing factors and recommend a supplement dose and duration. Take it exactly as advised, and mention kidney problems, pregnancy, medicines or other supplements before starting.

A balanced diet, suitable movement and safe outdoor activity can support general health. Persistent symptoms such as fatigue (/symptoms/fatigue/), joint pain (/symptoms/joint-pain/) or generalised weakness (/symptoms/generalised-weakness/) deserve assessment rather than being attributed automatically to vitamin D.

Seek prompt help after a fall with severe bone pain, inability to bear weight, or a suspected stress fracture (/conditions/stress-fracture/). Contact your clinician for worsening weakness, repeated infections (/symptoms/frequent-infections/) or persistent low mood (/symptoms/low-mood/), especially when daily activities are affected.

Ask what caused the low level, whether calcium and bone checks are needed, how long supplementation should continue, and when repeat testing or a review of symptoms is appropriate.