Vitamin D deficiency symptoms often develop slowly, making them easy to overlook. You might feel more tired than usual, notice aching muscles after simple activities, or struggle with persistent bone pain without realising that low vitamin D levels could be contributing to these problems.

Vitamin D is essential for maintaining healthy bones, supporting muscle function, and helping the body absorb calcium and phosphorus. Without enough of it, your body cannot efficiently use the calcium you consume, forcing it to draw calcium from your bones to maintain normal blood levels. Over time, this can weaken bones, reduce muscle strength, and increase the risk of falls and fractures.

According to the National Institutes of Health Office of Dietary Supplements, vitamin D plays a fundamental role in calcium absorption, bone mineralisation, and normal muscle function. Their evidence-based overview provides an excellent explanation of how vitamin D works in the body and why maintaining adequate levels is important for lifelong health: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

Although vitamin D deficiency is common worldwide, it is also one of the most treatable nutritional deficiencies. Recognising the symptoms early and seeking appropriate medical advice can prevent long-term complications and improve your overall well-being.

What Are Vitamin D Deficiency Symptoms?

Vitamin D deficiency symptoms commonly include fatigue, muscle weakness, bone pain, muscle aches, lower back pain, and an increased risk of falls or fractures. Severe deficiency may lead to osteomalacia in adults and rickets in children. Because these symptoms are common to many health conditions, a blood test is needed to confirm whether vitamin D deficiency is the cause.

Some people experience several symptoms simultaneously, while others have no noticeable symptoms despite having low vitamin D levels. This variation makes medical assessment particularly important.

What Does Vitamin D Do?

Vitamin D performs several essential functions throughout the body.

Its primary role is helping the intestine absorb calcium and phosphorus from food. These minerals are essential for building and maintaining strong bones throughout life.

Vitamin D also contributes to:

• Healthy muscle contraction
• Bone growth and repair
• Normal immune system function
• Maintenance of healthy teeth
• Regulation of calcium levels within the body

Without sufficient vitamin D, calcium absorption falls significantly. To compensate, the body begins releasing calcium stored in bones, gradually weakening them if the deficiency continues untreated.

The NHS also explains how vitamin D supports healthy bones, muscles and teeth, while outlining who may be at greater risk of deficiency and when supplements are recommended: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/

Early Vitamin D Deficiency Symptoms

The earliest signs are often subtle and easy to dismiss.

Many people initially assume they are simply tired from work, recovering more slowly after exercise, or feeling the effects of ageing.

Common early symptoms include:

• Persistent fatigue
• Reduced energy
• Muscle weakness
• General muscle aches
• Mild bone pain
• Lower back discomfort
• Reduced exercise performance
• Feeling physically drained
• Slower recovery after physical activity

Because these symptoms overlap with numerous medical conditions, they should never be used alone to diagnose vitamin D deficiency.

Instead, they should prompt further assessment, particularly in individuals with recognised risk factors.

Why Do Symptoms Develop Gradually?

Unlike many illnesses that develop suddenly, vitamin D deficiency usually progresses over months or even years.

Your body stores vitamin D in fat tissue and gradually uses these reserves when dietary intake or sunlight exposure becomes insufficient.

As these stores become depleted, calcium absorption declines.

Initially, your body compensates remarkably well.

Eventually, however, muscles and bones begin to suffer because they depend heavily on adequate calcium availability.

This explains why many people have low vitamin D levels for a long time before symptoms become noticeable.

Moderate Symptoms

As deficiency progresses, symptoms often become more difficult to ignore.

You may notice:

• Difficulty climbing stairs
• Weakness when standing from a chair
• Reduced grip strength
• Muscle cramps
• Poor balance
• Difficulty carrying shopping bags
• Persistent muscle soreness
• Increased risk of falls

People frequently describe feeling physically weaker than expected for their age or activity level.

These symptoms often affect everyday tasks long before serious bone complications develop.

Severe Vitamin D Deficiency Symptoms

When deficiency remains untreated for prolonged periods, more serious complications can occur.

Symptoms may include:

• Severe bone pain
• Walking difficulties
• Fragility fractures
• Significant muscle weakness
• Loss of mobility
• Difficulty performing routine activities

Adults with prolonged deficiency may develop osteomalacia, a condition characterised by poor bone mineralisation.

Children may develop rickets, where bones become soft and grow abnormally during development.

These complications are now uncommon in many developed countries but still occur, particularly in high-risk groups.

How Symptoms Progress

One important point is that symptom severity does not always reflect blood vitamin D levels.

Some individuals experience pronounced symptoms despite only modest reductions in vitamin D, while others remain symptom-free despite significant deficiency.

Who Is Most Likely to Develop Vitamin D Deficiency?

Although anyone can develop vitamin D deficiency, certain groups are at much higher risk.

These include:

• Older adults
• People with darker skin
• Individuals who spend little time outdoors
• People who regularly cover most of their skin
• Those living in northern climates
• Individuals with obesity
• Pregnant and breastfeeding women with additional risk factors
• People with digestive disorders
• Individuals with chronic kidney disease
• People taking medications that affect vitamin D metabolism

Recognising these risk factors helps identify people who may benefit from medical assessment.

Vitamin D Deficiency Symptoms in Women

Women often experience the same symptoms as men, but certain life stages increase their risk.

These include pregnancy, breastfeeding, and menopause.

Common symptoms include:

• Persistent tiredness
• Muscle weakness
• Bone discomfort
• Reduced stamina
• Muscle aches

After menopause, declining oestrogen levels accelerate bone loss.

When combined with vitamin D deficiency, this can substantially increase fracture risk

Vitamin D Deficiency Symptoms in Men

Men experience many of the same symptoms as women, although they often attribute them to strenuous work, ageing, or overtraining rather than an underlying nutritional deficiency.

Common symptoms include:

• Muscle weakness
• Reduced physical performance
• Persistent fatigue
• Lower back pain
• Muscle soreness that lasts longer than expected
• Reduced grip strength
• Stress fractures in physically active individuals

For men who exercise regularly, unexplained declines in strength, endurance, or recovery should not automatically be blamed on ageing or training intensity. If these changes persist, it’s worth discussing them with a healthcare professional.

Vitamin D Deficiency Symptoms in Older Adults

Older adults are among the groups most likely to develop vitamin D deficiency because the body’s ability to produce and activate vitamin D declines with age.

Common symptoms include:

• Difficulty walking
• Poor balance
• Frequent falls
• Progressive muscle weakness
• Hip or pelvic pain
• Slow recovery after illness
• Fragility fractures

Falls are a major cause of disability in older adults. While vitamin D alone is not a cure-all, maintaining adequate vitamin D levels is an important part of a broader strategy that includes strength training, good nutrition, and appropriate medical care.

Vitamin D Deficiency Symptoms in Children

Children require vitamin D for healthy growth and bone development.

Symptoms may include:

• Delayed growth
• Delayed walking
• Bowed legs
• Bone deformities
• Muscle weakness
• Irritability
• Delayed tooth eruption

Infants who are exclusively breastfed may require vitamin D supplementation depending on local health recommendations, as breast milk alone does not always provide sufficient vitamin D.

The NHS vitamin D guidance explains which groups, including infants and young children, may benefit from supplementation and how deficiency can be prevented:
https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/

What Causes Vitamin D Deficiency?

Vitamin D deficiency usually develops because several factors combine over time rather than from a single cause.

The most common causes include:

Limited Sun Exposure

Your skin naturally produces vitamin D when exposed to ultraviolet B (UVB) rays from sunlight.

People who spend most of their time indoors, work night shifts, wear clothing that covers most of their skin, or live in areas with limited winter sunlight often produce less vitamin D naturally.

Darker Skin

Melanin reduces the skin’s ability to produce vitamin D from sunlight.

People with darker skin generally require longer exposure to UVB sunlight to produce the same amount of vitamin D as someone with lighter skin.

Ageing

As we age, the skin becomes less efficient at producing vitamin D.

Kidneys also become less effective at converting vitamin D into its active form, increasing the likelihood of deficiency.

Low Dietary Intake

Only a small number of foods naturally contain significant amounts of vitamin D.

Without fortified foods or supplements, dietary intake alone is often insufficient, particularly during winter.

Digestive Disorders

Several medical conditions reduce vitamin D absorption, including:

• Coeliac disease
• Crohn’s disease
• Cystic fibrosis
• Chronic pancreatitis
• Bariatric surgery

Because vitamin D is a fat-soluble vitamin, conditions affecting fat absorption significantly increase the risk of deficiency.

Obesity

Vitamin D is stored within body fat.

People living with obesity often have lower circulating vitamin D because a greater proportion becomes stored in fat tissue rather than remaining available in the bloodstream.

Liver and Kidney Disease

The liver converts vitamin D into 25-hydroxyvitamin D, while the kidneys convert it into its active hormonal form.

Diseases affecting either organ can impair this process, leading to deficiency despite adequate sunlight or dietary intake.

Certain Medications

Some medicines interfere with vitamin D metabolism, including:

• Certain anticonvulsants
• Long-term corticosteroids
• Rifampicin
• Some antifungal medications

If you take long-term medication, your healthcare professional can advise whether monitoring vitamin D levels is appropriate.

How Is Vitamin D Deficiency Diagnosed?

Vitamin D deficiency cannot be diagnosed based on symptoms alone.

The most accurate way to confirm a deficiency is with a 25-hydroxyvitamin D (25(OH)D) blood test, which measures the body’s vitamin D stores.

Depending on your symptoms and medical history, your doctor may also request:

• Calcium
• Phosphate
• Parathyroid hormone (PTH)
• Alkaline phosphatase
• Kidney function tests
• Liver function tests

These tests help determine whether low vitamin D has affected bone metabolism or whether another condition is contributing to your symptoms.

The MedlinePlus guide to vitamin D deficiency explains how healthcare professionals diagnose and treat the condition in clear, patient-friendly language:
https://medlineplus.gov/vitaminddeficiency.html

Do You Need Routine Vitamin D Testing?

Not everyone needs a vitamin D blood test.

Current guidance from the Endocrine Society recommends targeted testing for people with symptoms, risk factors, or medical conditions associated with deficiency rather than routine screening of healthy adults.

Testing may be appropriate if you:

• Have persistent bone pain
• Experience unexplained muscle weakness
• Have osteoporosis
• Have recurrent fractures
• Have chronic kidney disease
• Have digestive disorders affecting nutrient absorption
• Are you taking medications that interfere with vitamin D metabolism

This approach helps ensure testing is used where it is most likely to improve patient care.

Can Vitamin D Deficiency Cause Fatigue?

Yes.

Persistent fatigue is one of the most commonly reported symptoms of vitamin D deficiency.

However, fatigue is a non-specific symptom that may also result from:

• Iron deficiency
• Anaemia
• Thyroid disorders
• Poor sleep
• Depression
• Chronic illness
• Certain medications

For this reason, fatigue alone should never be assumed to indicate low vitamin D.

A proper medical assessment is needed to identify the underlying cause.

Can Vitamin D Deficiency Cause Muscle Weakness?

Yes.

Vitamin D plays an important role in normal muscle function.

Low levels may contribute to:

• Reduced muscle strength
• Difficulty climbing stairs
• Problems standing from a seated position
• Reduced balance
• Increased risk of falls
• Slower walking speed

Older adults are particularly vulnerable because muscle weakness significantly increases fracture risk following falls.

Can Vitamin D Deficiency Cause Bone Pain?

Yes.

Vitamin D deficiency reduces calcium absorption, leading to poor bone mineralisation over time.

Bone pain associated with vitamin D deficiency is often described as:

• Deep aching pain
• Tenderness over the ribs
• Hip pain
• Pelvic pain
• Lower back pain
• Pain affecting several bones simultaneously

Unlike arthritis, the pain usually arises from weakened bones rather than inflamed joints.

Can Vitamin D Deficiency Affect Mood?

Some people with vitamin D deficiency report low mood, particularly during the winter months.

Research has identified an association between low vitamin D levels and mood disorders, but this relationship is complex.

Current evidence does not support using vitamin D supplements alone to treat depression or anxiety unless a deficiency is present.

Correcting a deficiency is important for overall health, but mental health concerns should always be assessed and managed appropriately by a healthcare professional.

Can Vitamin D Deficiency Cause Hair Loss?

Hair loss is frequently linked to vitamin D deficiency online, but the evidence is more nuanced than many articles suggest.

Research suggests that low vitamin D levels may be associated with certain forms of hair loss, particularly alopecia areata, an autoimmune condition that causes patchy hair loss. However, there is currently insufficient evidence to conclude that vitamin D deficiency directly causes common pattern hair loss or diffuse hair thinning.

Hair loss has many possible causes, including:

• Iron deficiency
• Thyroid disorders
• Hormonal changes
• Significant illness
• Stress
• Certain medications
• Genetics

If you are experiencing unexplained or persistent hair loss, a healthcare professional may recommend blood tests to investigate several possible causes rather than focusing solely on vitamin D.

How Is Vitamin D Deficiency Treated?

Treatment depends on several factors, including:

• Your blood test results
• The severity of the deficiency
• Your age
• Pregnancy status
• Existing medical conditions
• Kidney function
• Risk of fractures

Most people diagnosed with vitamin D deficiency are treated with vitamin D3 (cholecalciferol) because it is generally more effective at raising blood vitamin D levels than vitamin D2.

Treatment usually involves two stages:

Correcting the Deficiency

People with confirmed deficiency may be prescribed a higher dose of vitamin D for a limited period to restore healthy levels.

The exact dose varies depending on individual circumstances and should always follow medical advice.

Maintenance Therapy

Once healthy vitamin D levels have been restored, a lower maintenance dose may be recommended to prevent the deficiency from returning.

Some people, particularly those with chronic medical conditions or limited sun exposure, may require long-term supplementation.

The NHS guidance on vitamin D provides practical advice on supplements, including which groups are more likely to benefit from year-round supplementation:
https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/Foods Rich in Vitamin D

Although diet alone rarely corrects a significant deficiency, eating vitamin D-rich foods supports long-term health.

Including these foods regularly as part of a balanced diet can help maintain healthy vitamin D levels alongside appropriate sunlight exposure and supplementation where required.

Can You Get Enough Vitamin D From Sunlight?

Sunlight is the body’s primary natural source of vitamin D, but there is no universal recommendation for how much sun exposure is needed.

Vitamin D production depends on several factors, including:

• Skin colour
• Age
• Season
• Latitude
• Time of day
• Cloud cover
• Clothing
• Sunscreen use

Short periods of sunlight may be sufficient for some people during summer, while others may require supplements throughout the year.

Because excessive ultraviolet exposure increases the risk of skin cancer, healthcare professionals do not recommend prolonged unprotected sun exposure as a treatment for vitamin D deficiency.

How Long Does Recovery Take?

Recovery varies between individuals.

Many people notice improvements in fatigue and muscle strength within several weeks of starting treatment, while restoring healthy vitamin D stores may take several months.

Recovery depends on:

• The severity of deficiency
• The treatment prescribed
• Overall health
• Whether other nutritional deficiencies are present
• How consistently treatment is followed

Follow-up blood tests are often recommended to confirm that vitamin D levels have returned to an appropriate range.

What Happens If Vitamin D Deficiency Is Left Untreated?

Without treatment, vitamin D deficiency may gradually lead to more serious health problems.

Potential complications include:

• Osteomalacia
• Osteoporosis
• Fragility fractures
• Chronic muscle weakness
• Reduced mobility
• Increased risk of falls
• Reduced quality of life
• Rickets in children

Early diagnosis and treatment significantly reduce the likelihood of these complications.

How to Prevent Vitamin D Deficiency

Preventing vitamin D deficiency usually involves a combination of healthy lifestyle habits.

These include:

• Spending sensible time outdoors when appropriate.
• Eating foods naturally rich in vitamin D.
• Choosing fortified foods where available.
• Taking supplements if recommended by a healthcare professional.
• Managing medical conditions that affect nutrient absorption.
• Attending follow-up appointments if you have previously been diagnosed with deficiency.

People with long-term medical conditions or those at high risk may require ongoing monitoring.

Common Myths About Vitamin D Deficiency

Myth: Everyone with low vitamin D has symptoms.

False.

Many people have no noticeable symptoms despite having low vitamin D levels.

Myth: More vitamin D is always better.

False.

Taking excessive vitamin D supplements can lead to vitamin D toxicity, causing dangerously high calcium levels that may damage the kidneys and other organs.

Myth: Sunlight alone is enough for everyone.

False.

Age, geography, season, skin pigmentation, clothing, sunscreen use, and medical conditions all influence how much vitamin D your body can produce.

Myth: Fatigue always means vitamin D deficiency.

False.

Fatigue is a common symptom with many possible causes, including anaemia, thyroid disorders, sleep disorders, depression, chronic illness, and medication side effects.

Frequently Asked Questions

What is the first sign of vitamin D deficiency?

Fatigue, muscle weakness, and mild bone discomfort are among the earliest symptoms, although many people experience no symptoms during the initial stages.

Can vitamin D deficiency make you tired all the time?

Yes. Persistent fatigue is one of the most common symptoms, but tiredness alone cannot diagnose vitamin D deficiency because many medical conditions produce similar symptoms.

Which foods contain the most vitamin D?

Oily fish such as salmon, mackerel, sardines, trout, and herring are among the richest natural sources. Fortified dairy products, fortified cereals, egg yolks, and UV-exposed mushrooms also contribute.

Can vitamin D deficiency cause joint pain?

Some people report joint discomfort, but muscle pain and bone pain are more strongly associated with vitamin D deficiency than pain originating from the joints themselves.

Is vitamin D deficiency common?

Yes. It is one of the most common nutritional deficiencies worldwide, particularly among older adults, people with darker skin, individuals with limited sun exposure, and people with certain digestive disorders.

Can vitamin D deficiency be cured?

In most cases, yes.

Once identified, vitamin D deficiency can usually be corrected with appropriate supplementation, dietary improvements, and lifestyle changes. Some people with ongoing medical conditions may require long-term treatment to maintain healthy vitamin D levels.

Key Takeaways

Vitamin D deficiency is common, but it often develops gradually, allowing symptoms to go unnoticed for months or even years. Persistent fatigue, muscle weakness, bone pain, and an increased risk of falls are among the most common warning signs, although some people experience no symptoms at all.

A 25-hydroxyvitamin D blood test is the most reliable way to diagnose deficiency. Treatment typically involves vitamin D3 supplementation, sensible sunlight exposure, and a balanced diet that includes vitamin D-rich foods. Early diagnosis is important because an untreated deficiency can lead to weakened bones, muscle weakness, and a higher risk of fractures.

If you have persistent symptoms or belong to a high-risk group, speak with your healthcare professional. Identifying and treating vitamin D deficiency early can help protect your bones, maintain muscle strength, and support your long-term health.

Looking for more practical ways to improve your health? Browse our comprehensive collection of evidence-based articles in the Health and Wellness section, where you’ll find expert guidance on nutrition, preventive healthcare, healthy ageing, and everyday wellbeing.

References

• National Institutes of Health Office of Dietary Supplements. Vitamin D Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• NHS. Vitamin D. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
• MedlinePlus. Vitamin D Deficiency. https://medlineplus.gov/vitaminddeficiency.html
• Endocrine Society. Vitamin D for the Prevention of Disease: Clinical Practice Guideline. https://www.endocrine.org/clinical-practice-guidelines/vitamin-d-for-prevention-of-disease
• StatPearls. Vitamin D Deficiency. https://www.ncbi.nlm.nih.gov/books/NBK532266/