7 Signs of Vitamin D Deficiency: Symptoms That Can Go Unnoticed

Updated October 16, 2026 — Written by Dr. Shabbir Hussain, BPT, Registered Physiotherapist | Clinical Rehabilitation Specialist

Quick Answer

The most common 7 signs of vitamin D deficiency include persistent fatigue, muscle weakness, muscle aches, bone pain, muscle cramps, and mood changes. However, some people have low vitamin D levels without noticeable symptoms. A blood test measuring 25-hydroxyvitamin D [25(OH)D] can help identify a deficiency, and treatment depends on your vitamin D level, health conditions, and individual needs.

7 Signs of Vitamin D Deficiency

1. Persistent fatigue: Feeling unusually tired despite adequate rest may occur with vitamin D deficiency. Fatigue is nonspecific and can also result from anemia, thyroid disorders, poor sleep, or other conditions.

2. Muscle weakness: Low vitamin D levels can be associated with reduced muscle function. Some people notice difficulty climbing stairs, standing up from a chair, or completing everyday activities.

3. Bone pain: Vitamin D helps your body absorb calcium and phosphorus. Severe or prolonged deficiency can contribute to bone discomfort and softening of bones in adults, a condition called osteomalacia.

4. Muscle aches and cramps: Muscle discomfort, tenderness, or cramps may occur, particularly when severe deficiency affects calcium balance. These symptoms have many other possible causes.

5. Mood changes: Some people with vitamin D deficiency experience low mood or depressive symptoms. However, these symptoms alone cannot establish that vitamin D is responsible.

6. Reduced physical performance: Muscle weakness and discomfort can make walking, exercising, and daily tasks more difficult. Persistent or worsening weakness deserves assessment.

7. No obvious symptoms: This is an important point: vitamin D deficiency may remain unnoticed until a blood test or an evaluation for bone or muscle problems identifies it.

What Are the Symptoms of Very Low Vitamin D?

Very low vitamin D can cause significant muscle weakness, bone pain, and difficulty performing everyday movements. In severe cases, disrupted calcium and phosphorus balance may contribute to muscle spasms or cramps and osteomalacia in adults.

Children with severe deficiency may develop rickets, which can cause bone deformities and impaired skeletal development. Symptoms alone cannot tell you how low your vitamin D level is, so medical assessment and appropriate testing are important.

How Is Vitamin D Deficiency Diagnosed?

Vitamin D deficiency is assessed using a blood test called 25-hydroxyvitamin D, or 25(OH)D. Symptoms alone cannot confirm a deficiency or determine how severe it is.

The NIH notes that levels below 12 ng/mL are associated with deficiency, while levels of 20 ng/mL or higher are sufficient for most healthy people. Your healthcare professional should interpret the result in the context of your symptoms, medical history, and other risk factors.

Routine testing is not necessary for every healthy adult. Your clinician can determine whether testing is appropriate for you.

What Is the First Stage of Vitamin D Deficiency?

There is no universally accepted sequence of symptom stages for vitamin D deficiency. Early deficiency may cause no noticeable symptoms, while some people develop fatigue, muscle weakness, or bone discomfort. A 25-hydroxyvitamin D blood test can help assess vitamin D status; your clinician can interpret the result in the context of your health and risk factors.

How Can I Raise My Vitamin D Quickly?

The safest way to raise low vitamin D depends on how deficient you are.

• Take supplements as prescribed: A clinician may recommend a higher-dose treatment course for confirmed deficiency, followed by a maintenance dose.
• Include vitamin D-rich foods: Options include oily fish, egg yolks, mushrooms, and fortified milk or plant-based alternatives.
• Get sensible sunlight exposure: Sunlight helps your skin produce vitamin D, but the amount varies with skin pigmentation, season, location, clothing, and other factors. Avoid sunburn and excessive exposure.
• Follow up when advised: Your clinician may recommend repeat blood testing to assess your response.

Do not take large weekly or daily doses without medical guidance. Excess vitamin D can raise blood calcium and damage the kidneys or heart.

Can I Take Diltiazem With Vitamin D?

A potential interaction between diltiazem and vitamin D3 has been reported, although its clinical significance may vary. Ask your doctor or pharmacist to review your medications before starting a supplement, particularly if you take diltiazem for angina or another heart condition. Do not stop either medication without medical advice. Seek prompt medical attention if chest pain worsens or you develop new or worsening breathlessness.

How Physiotherapy Can Help

Physiotherapy may help people experiencing vitamin D deficiency-related muscle weakness, reduced mobility, or difficulty with everyday activities. A physiotherapist can assess strength, balance, walking ability, and fall risk, then tailor a rehabilitation plan.

Depending on symptoms and bone health, treatment may include gentle strengthening, balance training, functional exercises, and gradual activity progression. People with significant bone pain, suspected osteomalacia, or severe weakness should obtain medical assessment before starting strenuous exercise.

The key takeaway: Persistent fatigue, muscle weakness, and bone pain deserve attention, but they do not confirm vitamin D deficiency. Appropriate testing and clinician-guided treatment are more reliable than self-diagnosis.

Medical Sources

1. NIH Office of Dietary Supplements — Vitamin D: Fact Sheet for Health Professionals

2. Cleveland Clinic — Vitamin D Deficiency

3. NHS — How and When to Take Colecalciferol

4. Drugs.com — Diltiazem and Vitamin D3 Interaction Checker