Symptoms of Vitamin D Deficiency

Vitamin D deficiency often causes no obvious symptoms at all, especially when mild — which is exactly why it's so commonly missed without a blood test.

Subtle, Easily Overlooked Symptoms

• Persistent fatigue or low energy, often mistaken for normal tiredness
• General muscle weakness
• Mood changes, including low mood
• Getting sick more often than usual, since vitamin D also supports immune function

More Specific Symptoms With Longer or More Severe Deficiency

• Bone pain, particularly in the lower back, hips, or legs
• Muscle aches and cramps
• Increased risk of fractures from relatively minor falls
• In children, delayed growth or bone deformities (rickets) in severe, prolonged deficiency; in adults, the equivalent bone-softening condition is called osteomalacia, which can cause bone pain and muscle weakness; in adults, the equivalent bone-softening condition is called osteomalacia, which can cause bone pain and muscle weakness; in adults, the equivalent bone-softening condition is called osteomalacia, which can cause bone pain and muscle weakness

Why Symptoms Alone Aren't Reliable

Because these symptoms overlap with so many other common conditions — from thyroid problems to depression to simply being overworked — a blood test (25-hydroxyvitamin D) is the only way to actually confirm a deficiency rather than guessing from symptoms.