Side effects of low vitamin D

Vitamin D helps the body absorb calcium and supports normal muscle and bone function. Low levels may be associated with tiredness, generalised weakness, muscle aches, joint pain or low mood, although these symptoms can arise for many reasons. More persistent deficiency can soften or weaken bones and may increase vulnerability to problems such as a stress fracture. Low vitamin D does not explain every episode of fatigue or frequent infections, so symptoms need context and, when appropriate, testing.

Book a GP appointment if symptoms persist, affect walking or exercise, or occur alongside limited sunlight exposure, a restrictive diet, or a condition that affects absorption. A clinician can review your history and decide whether a blood test is needed. Treatment may involve a prescribed or recommended supplement, dietary changes, and safe outdoor activity. Do not take high-dose supplements without advice, because excess vitamin D can also harm health.

Seek prompt assessment for sudden severe bone pain, inability to bear weight, a suspected fracture, marked muscle weakness, confusion, or repeated vomiting. These symptoms may need a different or more urgent explanation than low vitamin D alone. Arrange review sooner if weakness is worsening or you are having frequent falls.

Ask whether testing is appropriate, what dose and duration of supplementation you need, when to repeat assessment, and whether another condition could explain your symptoms.