Signs of Vitamin D Deficiency Most People Ignore

Vitamin D deficiency often causes no obvious symptoms, but persistent fatigue, muscle weakness, deep bone discomfort, frequent aches and difficulty with everyday movements can be warning signs. These problems are not specific to vitamin D deficiency, so diagnosis should be based on medical assessment and, when appropriate, a blood test rather than symptoms alone.

Why vitamin D deficiency can be easy to miss

Vitamin D helps the body absorb calcium and supports normal bone mineralisation, muscle function and several other physiological processes. When vitamin D remains very low, children may develop rickets and adults may develop osteomalacia, a condition in which bones become inadequately mineralised and painful.

Early deficiency may be silent. When symptoms occur, they often overlap with stress, poor sleep, anaemia, thyroid disorders, chronic pain conditions and many other health problems. This is why people may ignore the symptoms or attribute them to a busy routine.

Signs of vitamin D deficiency most people ignore

1. Persistent, unexplained fatigue

Feeling unusually tired despite adequate rest may occur in people with vitamin D deficiency. Fatigue is extremely common and has many possible causes, so it should not be treated as proof of low vitamin D.

Consider seeking medical advice when fatigue is persistent, worsening or accompanied by breathlessness, palpitations, weight changes, fever, low mood, bleeding or significant weakness. A clinician may need to consider anaemia, thyroid disease, sleep disorders, infection, medication effects and other explanations.

2. Difficulty rising from a chair

Vitamin D deficiency can contribute to proximal muscle weakness, meaning weakness in muscles close to the trunk. A person may notice difficulty standing from a low chair, climbing stairs, getting out of a car or lifting their arms overhead.

This type of weakness may be dismissed as ageing, inactivity or lack of fitness. New, progressive or one-sided weakness requires medical assessment because neurological, muscular and metabolic conditions can cause similar problems.

3. A heavy or unsteady walking pattern

Severe deficiency and osteomalacia may affect walking. Some people develop a slower, uncomfortable or waddling gait because of muscle weakness and pain around the hips, pelvis or legs.

Repeated stumbling, falls or a sudden change in walking ability should not be ignored. Urgent evaluation is appropriate when walking difficulty begins suddenly or occurs with facial drooping, speech difficulty, severe back pain, numbness, loss of bladder control or weakness on one side.

4. Deep bone pain rather than ordinary muscle soreness

Vitamin D deficiency may cause deep, aching discomfort in areas such as the lower back, hips, pelvis, ribs, thighs or legs. The discomfort may be difficult to localise and can sometimes be mistaken for general body pain.

Bone pain is different from the temporary muscle soreness that follows unfamiliar exercise. Persistent pain, night pain, marked tenderness or pain after a minor injury deserves professional assessment.

5. General muscle aches or cramps

Some people with low vitamin D report widespread aches, muscle discomfort or cramps. However, these symptoms are nonspecific and may also be related to dehydration, strenuous activity, electrolyte disturbances, medication effects or other medical conditions.

Do not assume that every muscle ache requires a high-dose vitamin D supplement. The pattern, duration and severity of symptoms matter, as do the person’s diet, medical history and risk factors.

6. Reduced physical performance

A previously manageable walk, staircase or household task may begin to feel unusually difficult. Reduced muscle strength and pain can gradually limit activity, which may then cause further deconditioning.

This change is easy to overlook because it often develops slowly. Keeping track of functional changes, such as needing to use the arms to stand up, can provide useful information during a medical consultation.

7. Bone tenderness

Osteomalacia may cause tenderness when pressure is applied over certain bones. Tenderness around the ribs, breastbone, shins or pelvis is not a reliable home test, but persistent focal tenderness should be discussed with a healthcare professional.

Do not repeatedly press painful areas to test yourself. Localised tenderness can also result from injury, inflammation, infection or, less commonly, more serious bone disease.

8. Recurrent falls in an older adult

Muscle weakness, impaired balance and poor bone health can increase the consequences of falls. Vitamin D status may be one part of a broader fall-risk assessment, particularly in an older person with limited mobility, poor nutrition or little sunlight exposure.

Falls are rarely caused by one factor. Vision problems, low blood pressure, sedating medicines, neurological disorders, footwear and hazards within the home may all contribute.

9. Stress fractures or fractures after minor trauma

Long-standing severe vitamin D deficiency can impair bone mineralisation. A fracture after a low-impact fall, recurrent stress injury or unexplained bone pain may prompt assessment of vitamin D and overall bone health.

Vitamin D is only one consideration. Age, menopause, calcium intake, steroid treatment, low body weight, smoking, physical activity and osteoporosis can also affect fracture risk.

10. Symptoms that persist despite rest

Ordinary tiredness and muscle soreness usually improve when the underlying trigger resolves. Symptoms that continue for weeks, interfere with daily activities or progressively worsen should not simply be attributed to vitamin D deficiency or treated without evaluation.

Symptoms that are often wrongly blamed on vitamin D

Online discussions frequently attribute low mood, hair loss, recurrent infections, poor concentration, weight gain and almost every type of pain to low vitamin D. Research has identified associations between vitamin D status and several health conditions, but an association does not prove that deficiency caused an individual’s symptom.

Supplementation is not a guaranteed treatment for vague symptoms, and correcting vitamin D will not necessarily resolve a problem caused by another condition. A balanced assessment is safer than assuming a single vitamin deficiency explains everything.

Who is more likely to develop vitamin D deficiency?

A person may have a higher risk of low vitamin D when one or more of the following apply:

• Very limited exposure to sunlight, including spending most of the day indoors
• Clothing that covers most of the skin
• Darker skin, which produces less vitamin D from the same amount of sunlight exposure
• Older age
• Conditions that reduce fat absorption, such as coeliac disease, Crohn’s disease or some forms of liver and pancreatic disease
• Previous bariatric or intestinal surgery
• Obesity, which can alter circulating vitamin D levels
• Kidney or liver disease affecting vitamin D metabolism
• Use of certain medicines, including some antiseizure treatments and long-term glucocorticoids
• A diet containing few vitamin D sources, especially when combined with limited sunlight exposure
• Pregnancy, infancy or other periods when nutritional requirements require particular attention

How vitamin D deficiency is diagnosed

The usual laboratory measure of vitamin D status is serum 25-hydroxyvitamin D, written as 25(OH)D. A clinician may also request calcium, phosphate, alkaline phosphatase, parathyroid hormone, kidney-function tests or other investigations depending on the symptoms.

Professional organisations do not generally recommend routine vitamin D testing for every healthy person without a specific indication. Testing is more useful when symptoms, risk factors, bone disease, malabsorption or another clinical concern make the result likely to affect management.

Definitions of deficiency and insufficiency are not completely uniform across organisations and clinical settings. Results therefore need to be interpreted alongside the person’s health, age, symptoms, risk factors and local guidance.

Should you take vitamin D without a blood test?

Many countries recommend a routine preventive intake for certain groups, particularly during seasons with limited sunlight. These public-health doses are different from the larger treatment regimens used for confirmed deficiency.

Healthy adults should not assume that taking progressively higher doses will provide greater benefit. The 2024 Endocrine Society guideline advises that healthy adults younger than 75 generally do not need vitamin D above the established recommended daily intake solely for disease prevention.

A clinician or pharmacist can advise whether routine supplementation is appropriate under local guidance. People with kidney disease, high calcium levels, sarcoidosis, some endocrine disorders, recurrent kidney stones or medicines that affect calcium metabolism should seek individual advice.

Why high-dose self-treatment can be harmful

Vitamin D is fat-soluble and can accumulate when excessive doses are taken over time. Toxicity can produce high blood calcium, potentially causing nausea, vomiting, constipation, excessive thirst, frequent urination, dehydration, confusion, muscle weakness and kidney injury.

Do not combine multiple supplements without checking their vitamin D content. Products labelled for weekly or monthly treatment may contain much more than a standard daily supplement and should not be used more frequently than directed.

Practical steps to support healthy vitamin D levels

1. Review your risk factors: Consider sunlight exposure, skin coverage, diet, age, medicines and digestive conditions.
2. Use food sources where practical: Oily fish, egg yolks and foods fortified with vitamin D can contribute to intake, although food alone may not be sufficient for everyone.
3. Follow local sunlight-safety guidance: Sun exposure must be balanced against the risk of sunburn and skin cancer. Avoid deliberately burning the skin.
4. Choose supplements carefully: Use an age-appropriate preventive dose recommended by a recognised health authority or healthcare professional.
5. Seek assessment for persistent symptoms: Fatigue, pain and weakness may require evaluation for causes beyond vitamin D.

When to contact a healthcare professional

Arrange a medical review if you have persistent bone pain, progressive muscle weakness, repeated falls, difficulty walking, a fracture after minor trauma or symptoms combined with major risk factors for deficiency.

Prompt assessment is particularly important for a child with delayed growth, bowed legs, swollen wrists, delayed walking or muscle weakness. Infants with seizures, breathing difficulty or muscle spasms need urgent medical care, as severe calcium disturbances can be dangerous.

Seek urgent help for sudden weakness, inability to walk, severe confusion, a suspected fracture, seizures or symptoms suggesting a neurological emergency. These should not be assumed to result from vitamin D deficiency.

Key message

The commonly ignored signs of vitamin D deficiency are subtle changes in energy, muscle strength, mobility and bone comfort. Because these symptoms overlap with many other conditions, the safest approach is to recognise the pattern, consider personal risk factors and seek appropriate assessment instead of diagnosing yourself from symptoms alone.

Medical disclaimer: This article by Dr. Haiqa Afzal is for general educational purposes and does not provide an individual diagnosis or treatment plan. Consult a qualified healthcare professional before starting high-dose vitamin D, changing medication or interpreting laboratory results.