Vitamin D Deficiency Symptoms: Signs, Causes & Treatment
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Vitamin D deficiency can weaken bones and affect normal muscle function, but many people with a low blood level have no obvious symptoms.
When symptoms do occur, they may include bone pain, muscle weakness or aches, difficulty with physical function, and fractures. In children, severe deficiency can cause rickets. In adults, it can lead to osteomalacia, a condition in which bones become soft and painful.
This guide explains the possible symptoms of vitamin D deficiency, common causes, risk factors, blood testing, food sources, treatment principles, supplement safety, and when medical assessment is important.
What Is Vitamin D?
Vitamin D is a fat-soluble vitamin that helps the body absorb calcium. Calcium is one of the main building blocks needed for normal bone formation.
Vitamin D also has roles in normal muscle, nerve, and immune-system function.
The body can make vitamin D when bare skin is exposed to ultraviolet B radiation from sunlight. Vitamin D is also available from certain foods, fortified products, and supplements.
What Is Vitamin D Deficiency?
Vitamin D deficiency means that the body does not have enough vitamin D to support normal health and mineral balance.
Clinicians usually assess vitamin D status using a blood test called 25-hydroxyvitamin D, written as 25(OH)D.
The National Academies' Food and Nutrition Board uses the following general interpretation for bone and overall health in most people:
| 25(OH)D Blood Level | General Interpretation |
|---|---|
| Below 12 ng/mL (30 nmol/L) | Associated with vitamin D deficiency |
| 12 to below 20 ng/mL (30 to below 50 nmol/L) | Generally considered inadequate for bone and overall health in healthy individuals |
| 20 ng/mL (50 nmol/L) or higher | Generally sufficient for most people |
| Above 50 ng/mL (125 nmol/L) | May be associated with adverse effects, particularly at higher levels |
Laboratories and professional organizations may use different terminology or thresholds depending on the clinical context. A test result should be interpreted alongside symptoms, medical history, medication, calcium levels, and other risk factors.
Vitamin D Deficiency Symptoms at a Glance
| Possible Feature | How It May Appear | Important Limitation |
|---|---|---|
| No obvious symptoms | Deficiency is discovered through testing or evaluation of risk factors | This is common |
| Bone pain | Persistent or diffuse discomfort, sometimes involving the back, ribs, pelvis, or legs | Bone pain has many possible causes |
| Muscle weakness | Difficulty rising from a chair, climbing stairs, or performing usual activities | Neurological and muscular conditions can cause similar symptoms |
| Muscle aches | Generalized aching or discomfort | Not specific to vitamin D deficiency |
| Weak or soft bones | Osteomalacia in adults or rickets in children | Requires medical diagnosis |
| Fractures | Broken bones after low-impact injury or reduced bone strength | Osteoporosis and other conditions also increase fracture risk |
Can You Have Vitamin D Deficiency Without Symptoms?
Yes. Many people with a low vitamin D blood level do not notice clear symptoms.
This is one reason symptoms are not a reliable screening tool. Mild fatigue, aches, or reduced energy are common in the general population and may result from sleep deprivation, anemia, thyroid disease, infection, depression, medication, or many other conditions.
Testing is most useful when there is a clinical reason rather than simply because a person has one vague symptom.
Bone Pain
Vitamin D helps maintain normal calcium and phosphate balance. Severe or prolonged deficiency can impair bone mineralization.
In adults, this can lead to osteomalacia, which may cause bone pain and tenderness.
Bone pain should be assessed when it is persistent, worsening, associated with a fracture, or accompanied by weight loss, fever, weakness, or a history of cancer.
Muscle Weakness and Aches
Vitamin D contributes to normal muscle function. Significant deficiency may be associated with muscle weakness or aches.
A person may notice difficulty:
- Rising from a low chair
- Climbing stairs
- Walking for the usual distance
- Maintaining balance
- Completing ordinary physical tasks
Sudden one-sided weakness, facial drooping, speech difficulty, or loss of coordination is not a typical nutritional symptom and requires emergency medical care.
Fatigue and Low Energy
Some people with low vitamin D report fatigue, but fatigue is not specific enough to diagnose deficiency.
Other common explanations include:
- Insufficient or poor-quality sleep
- Iron-deficiency anemia
- Vitamin B12 deficiency
- Thyroid disease
- Infection
- Depression or anxiety
- Medication effects
- Sleep apnea
- Inadequate calorie or protein intake
Testing may be appropriate when fatigue occurs with risk factors, bone pain, muscle weakness, malabsorption, or another relevant medical condition.
Frequent Illness or “Low Immunity”
Vitamin D has a role in normal immune function, but frequent infections do not prove deficiency.
Many factors influence infection risk, including exposure, vaccination status, age, chronic disease, sleep, smoking, medication, and immune disorders.
Vitamin D supplements should not be promoted as a guaranteed way to prevent or treat infections.
Vitamin D Deficiency in Children
Severe vitamin D deficiency in children can cause rickets, a condition that softens and weakens growing bones.
Possible features can include:
- Delayed growth
- Bone pain or tenderness
- Muscle weakness
- Delayed motor development
- Bowed legs or other skeletal changes
- Dental problems
- Fractures
Infants and children with suspected rickets require pediatric assessment. Treatment should not be improvised with adult supplements.
Vitamin D Deficiency in Adults
Severe deficiency in adults can cause osteomalacia.
Possible features include:
- Diffuse bone pain
- Muscle weakness
- Difficulty walking
- Reduced physical function
- Weak bones and fractures
Vitamin D deficiency can coexist with osteoporosis, but the conditions are not identical. Osteoporosis involves reduced bone density and fracture risk, while osteomalacia involves impaired bone mineralization.
What Causes Vitamin D Deficiency?
Limited Sun Exposure
The body produces vitamin D when skin is exposed to ultraviolet B radiation. Production may be limited by spending little time outdoors, covering most of the skin, seasonal changes, latitude, air pollution, and the use of sun protection.
Sun exposure is not a risk-free treatment. Excess ultraviolet exposure increases the risk of skin damage and skin cancer. There is no universal safe sun-exposure prescription for every skin type, location, season, and individual.
Darker Skin Pigmentation
Melanin reduces the skin's ability to produce vitamin D from sunlight. People with darker skin may therefore require more ultraviolet exposure to produce the same amount of vitamin D as people with lighter skin.
This is a risk factor, not a diagnosis. Diet, supplement use, location, clothing, and health conditions also matter.
Low Intake of Vitamin D Foods
Few foods naturally contain substantial vitamin D. People who avoid fortified dairy products, fortified plant milks, eggs, or fatty fish may have a lower dietary intake.
Fat Malabsorption
Vitamin D is fat-soluble. Conditions that reduce fat absorption can increase deficiency risk.
Examples include:
- Celiac disease
- Crohn's disease
- Ulcerative colitis in some circumstances
- Cystic fibrosis
- Certain liver or pancreatic disorders
- Some forms of bariatric surgery
Obesity
People with obesity may have lower circulating 25(OH)D levels because vitamin D is distributed into a larger volume of body tissue and stored in fat.
This does not justify taking a high dose without professional guidance.
Older Age
Older skin produces less vitamin D from sunlight. Older adults may also spend less time outdoors, eat less vitamin D, or have conditions that affect absorption.
Kidney or Liver Disease
The liver and kidneys help convert vitamin D into forms used by the body. Significant disease can disrupt vitamin D metabolism and may require specialized treatment rather than a standard over-the-counter product.
Medicines That Can Affect Vitamin D
Certain medicines can influence vitamin D metabolism or absorption.
| Medicine Category | Possible Issue | Recommended Action |
|---|---|---|
| Orlistat | Can reduce absorption of fat-soluble vitamins | Ask about supplement timing and monitoring |
| Some cholesterol-lowering bile-acid sequestrants | May reduce vitamin D absorption | Discuss timing and monitoring with a pharmacist |
| Long-term corticosteroids | Can affect calcium and vitamin D metabolism and bone health | Bone-health assessment may be appropriate |
| Certain antiseizure medicines | May increase vitamin D breakdown | Testing or supplementation may be recommended clinically |
Do not stop or change prescribed medication because of concern about vitamin D. Ask a doctor or pharmacist whether testing or supplementation is appropriate.
Who Is at Higher Risk?
- Breastfed infants who do not receive recommended vitamin D supplementation
- Older adults
- People with limited sun exposure
- People with darker skin pigmentation
- People with fat-malabsorption disorders
- People who have undergone certain bariatric procedures
- People with obesity
- People with significant liver or kidney disease
- People using medicines that alter vitamin D metabolism or absorption
- People with osteomalacia, osteoporosis, or recurrent fractures
How Is Vitamin D Deficiency Diagnosed?
25-Hydroxyvitamin D Blood Test
The standard test for vitamin D status is 25-hydroxyvitamin D, or 25(OH)D.
The active hormone form, 1,25-dihydroxyvitamin D, is not usually the correct test for routine vitamin D status because it can remain normal or become elevated even when stores are low.
Additional Tests
Depending on the situation, a clinician may also assess:
- Calcium
- Phosphate
- Parathyroid hormone
- Alkaline phosphatase
- Kidney function
- Liver function
- Bone density
Medical History
A useful assessment includes diet, sun exposure, skin pigmentation, medication, gastrointestinal symptoms, fractures, bone pain, pregnancy, surgery, and chronic disease.
Does Everyone Need a Vitamin D Test?
No.
The Endocrine Society's 2024 guideline suggests against routine vitamin D testing in generally healthy adults when there is no established clinical reason.
Testing may still be appropriate when there are:
- Symptoms of osteomalacia or rickets
- Bone pain or muscle weakness
- Low bone density or fractures
- Malabsorption
- Kidney or liver disease
- Medication affecting vitamin D
- A condition requiring monitored treatment
How Much Vitamin D Do People Need?
| Life Stage | Recommended Daily Amount |
|---|---|
| Birth to 12 months | 400 IU (10 mcg) |
| Children and adults aged 1–70 | 600 IU (15 mcg) |
| Adults aged 71 and older | 800 IU (20 mcg) |
| Pregnancy and breastfeeding | 600 IU (15 mcg) |
These are general recommended intakes, not treatment doses for diagnosed deficiency.
Vitamin D Treatment
Treatment depends on the blood level, age, symptoms, cause, absorption, kidney and liver function, pregnancy, and other medical factors.
Food and Fortified Products
Diet can help improve routine intake but may not be enough to correct significant deficiency by itself.
Oral Vitamin D
Vitamin D3, or cholecalciferol, is commonly used in supplements. Vitamin D2, or ergocalciferol, is another available form.
A clinician may use a temporary replacement regimen followed by a lower maintenance amount. The exact plan should be individualized rather than copied from another person's prescription.
Treating the Cause
Deficiency may return if malabsorption, medication effects, poor intake, limited exposure, or another underlying issue is not addressed.
Foods That Contain Vitamin D
| Food Category | Examples | Practical Note |
|---|---|---|
| Fatty fish | Salmon, trout, mackerel, sardines | Among the best natural dietary sources |
| Fish liver oils | Cod liver oil | Can contain high vitamin A; check the label carefully |
| Egg yolks | Whole eggs | Usually provide a modest amount |
| UV-exposed mushrooms | Selected commercially treated mushrooms | Usually provide vitamin D2 |
| Fortified milk or plant beverages | Check local labels | Fortification varies by country and brand |
| Fortified cereals | Selected breakfast cereals | Check serving size and added sugar |
Vitamin D2 vs Vitamin D3
Vitamin D2 is ergocalciferol, while vitamin D3 is cholecalciferol.
Both can raise blood vitamin D levels. Vitamin D3 may raise and maintain 25(OH)D more effectively in many comparisons, but the appropriate product depends on the dose, formulation, dietary preference, and clinical plan.
People who prefer a plant-based D3 product can look for vitamin D3 derived from lichen.
Can Vitamin D Deficiency Cause Hair Loss?
Low vitamin D has been studied in relation to some hair-loss conditions, but hair loss is not a specific or reliable symptom of vitamin D deficiency.
Other causes include iron deficiency, thyroid disease, genetics, illness, stress, medication, hormonal changes, and scalp disorders.
Hair loss should be assessed based on its pattern and accompanying symptoms rather than treated automatically with vitamin D.
Can Vitamin D Deficiency Cause Depression?
Low vitamin D levels are associated with depression in some observational studies, but association does not prove that deficiency is the cause.
Vitamin D supplementation should not replace mental-health assessment, psychotherapy, or prescribed treatment.
Can Vitamin D Deficiency Cause Weight Gain?
People with obesity often have lower circulating vitamin D levels, but low vitamin D has not been established as a simple direct cause of weight gain.
Weight change involves calorie intake, physical activity, sleep, medication, hormones, genetics, and many other factors.
Can Vitamin D Deficiency Cause Back Pain?
Osteomalacia can cause bone pain, including discomfort involving the back or pelvis.
Most back pain is caused by mechanical or musculoskeletal issues rather than vitamin D deficiency. Persistent pain, neurological symptoms, fever, unexplained weight loss, cancer history, or loss of bladder or bowel control requires medical assessment.
Can Vitamin D Deficiency Cause Dizziness?
Dizziness is not a specific sign of vitamin D deficiency.
Possible causes include dehydration, low blood pressure, anemia, medication, inner-ear disease, heart rhythm problems, low blood sugar, anxiety, and neurological conditions.
Vitamin D Supplement Safety
Vitamin D is fat-soluble and can accumulate when taken in excessive amounts.
The adult tolerable upper intake level is generally 4,000 IU (100 mcg) per day from all sources unless a healthcare professional recommends a higher treatment amount for a specific reason.
The upper limit is not a recommended target.
Symptoms of Too Much Vitamin D
Vitamin D toxicity usually results from excessive supplement use rather than food or ordinary sun exposure.
It can cause high blood calcium, leading to:
- Nausea or vomiting
- Loss of appetite
- Constipation
- Excessive thirst
- Frequent urination
- Dehydration
- Weakness
- Confusion
- Kidney stones or kidney injury
- Abnormal heart rhythm in severe cases
Vitamin D Medication Interactions
Vitamin D supplements can interact with medicines or affect calcium balance.
Extra caution may be needed with:
- Thiazide diuretics
- Orlistat
- Corticosteroids
- Certain antiseizure medicines
- Medicines that affect calcium or kidney function
Ask a pharmacist to review the exact product and medication list.
Who Should Speak With a Healthcare Professional First?
- People with kidney disease or kidney stones
- People with high blood calcium
- People with sarcoidosis or another granulomatous disorder
- People with significant liver disease
- People with malabsorption
- Pregnant or breastfeeding individuals considering high doses
- Children requiring more than routine preventive supplementation
- People taking interacting medicines
- People with recurrent fractures, bone pain, or muscle weakness
Common Mistakes
Diagnosing Deficiency From Fatigue Alone
Fatigue is common and has many possible causes.
Taking a High-Dose Product Without Testing or Guidance
Treatment amounts are not the same as routine maintenance intake.
Assuming More Is Better
High blood levels and excessive intake can cause harm.
Ignoring Calcium and Kidney Health
Vitamin D changes calcium absorption, so calcium balance and kidney function matter.
Expecting Vitamin D to Cure Unrelated Conditions
Vitamin D is essential, but supplements do not automatically treat fatigue, depression, infections, hair loss, or weight gain.
When to Seek Medical Advice
Arrange an assessment if you have:
- Persistent bone pain
- Muscle weakness or difficulty walking
- Repeated low-impact fractures
- A child with delayed growth or skeletal changes
- Known malabsorption
- Kidney or liver disease
- Long-term medicines that affect vitamin D
- A very low or very high vitamin D test result
Related Vitamin and Mineral Guides
- The Complete Guide to Magnesium Supplements
- Magnesium Deficiency Symptoms
- Can You Take Magnesium Every Day?
Test and Treat for a Clear Clinical Reason
Many people with vitamin D deficiency have no obvious symptoms, while common complaints such as fatigue and aches have many possible causes. Testing and treatment are most useful when symptoms, bone disease, malabsorption, medication, or another risk factor provides a clear clinical reason.
Final Thoughts
Vitamin D deficiency may cause no symptoms at all. When deficiency is significant, possible features include bone pain, muscle weakness or aches, weak or soft bones, and fractures.
Children can develop rickets, while adults can develop osteomalacia. Risk is higher with limited sun exposure, darker skin pigmentation, older age, obesity, malabsorption, certain medicines, and significant kidney or liver disease.
Symptoms alone cannot confirm deficiency. The standard assessment uses a 25-hydroxyvitamin D blood test interpreted within the person's medical context. Avoid self-prescribing high treatment doses, because excessive vitamin D can cause dangerous high calcium levels.
Frequently Asked Questions
What are the main symptoms of vitamin D deficiency?
Many people have no symptoms. More significant deficiency may cause bone pain, muscle weakness or aches, weak or soft bones, and fractures.
Can vitamin D deficiency cause fatigue?
Fatigue can occur, but it is not specific to vitamin D deficiency. Poor sleep, anemia, thyroid disease, infection, depression, and medication are common alternatives.
How is vitamin D deficiency tested?
The standard test is a blood test for 25-hydroxyvitamin D, also called 25(OH)D.
What level is considered vitamin D deficient?
The Food and Nutrition Board considers levels below 12 ng/mL associated with deficiency, while 12 to below 20 ng/mL is generally inadequate for bone and overall health in healthy people. Clinical interpretation can vary.
Does everyone need a vitamin D test?
No. Routine testing is not recommended for all healthy adults. Testing may be useful when symptoms, fractures, bone disease, malabsorption, medication, or another clinical risk is present.
Can vitamin D deficiency cause bone pain?
Yes. Severe or prolonged deficiency can cause osteomalacia in adults, which may lead to bone pain and muscle weakness.
Can vitamin D deficiency cause hair loss?
Low vitamin D is associated with some hair-loss conditions, but hair loss is not a specific sign and has many other possible causes.
What foods contain vitamin D?
Sources include fatty fish, fish liver oils, egg yolks, UV-exposed mushrooms, and fortified milk, plant beverages, or cereals.
How much vitamin D do adults need?
Most adults aged 19 to 70 need 600 IU (15 mcg) daily, while adults aged 71 and older need 800 IU (20 mcg).
Can too much vitamin D be harmful?
Yes. Excess supplement use can cause high blood calcium, leading to nausea, vomiting, constipation, thirst, frequent urination, weakness, confusion, and kidney injury.
Who is most at risk of vitamin D deficiency?
Higher-risk groups include older adults, people with limited sun exposure, darker skin pigmentation, obesity, fat-malabsorption conditions, certain bariatric procedures, and some kidney or liver disorders.
Is vitamin D3 better than vitamin D2?
Both can raise vitamin D levels. Vitamin D3 may raise and maintain 25(OH)D more effectively in many comparisons, but the appropriate product depends on the clinical plan and dietary preference.
About the Author
Rebecca Morgan is a medical nutrition writer specializing in vitamins, minerals, bone health, nutrient deficiencies, and evidence-informed supplement education. Her work focuses on helping readers understand clinical nutrition without encouraging unnecessary testing or excessive supplementation.
Content reviewed and published by GetMySupplement Editorial Team. Last updated August 1, 2026.
This article is for educational purposes only and should not be considered medical advice. Consult a qualified healthcare professional for diagnosis and treatment, especially if you have bone pain, muscle weakness, fractures, kidney or liver disease, malabsorption, take medication, are pregnant or breastfeeding, or are considering a high-dose supplement for yourself or a child.
References
- NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals
- NIH Office of Dietary Supplements: Vitamin D Consumer Fact Sheet
- MedlinePlus: Vitamin D Deficiency
- MedlinePlus: Vitamin D Test
- Endocrine Society: Vitamin D for the Prevention of Disease Guideline
- MedlinePlus: Hypervitaminosis D