11 Key Symptoms of Vitamin D Deficiency in Children

The symptoms of vitamin D deficiency in children can be easy to miss because many children have no clear symptoms at first. When deficiency becomes more severe, signs can include bone pain, muscle weakness, poor growth, delayed walking, changes in the legs or wrists, and fractures. Severe deficiency can lead to rickets and dangerously low calcium.

This is why symptoms alone cannot tell you whether your child has low vitamin D.

A child who looks healthy can still be at risk, while tiredness or leg pain can have many causes that have nothing to do with vitamin D.

This article is for general information and education. It does not replace medical advice, diagnosis, or treatment.

For more guides about vitamins, minerals, deficiencies, and nutrition, visit the NextFitLife Nutrition and Vitamins Hub.

What does vitamin D deficiency look like in children?

Sometimes, it looks like nothing at all.

That is one of the most useful facts for parents to know.

Children with low vitamin D do not always have a clear symptom that points to the problem. Nationwide Children's Hospital notes that most people with vitamin D deficiency have no symptoms.

When symptoms do appear, they tend to involve bones and muscles because vitamin D helps the body absorb calcium and phosphorus. These minerals are needed for normal bone mineralization, which is the process that makes growing bones strong.

Severe or long lasting deficiency can cause rickets. In rickets, growing bones become soft and weak. This can lead to pain, changes in bone shape, poor growth, and problems with movement.

NIH also notes that severe rickets can cause developmental delay, dental problems, spasms, seizures, and other complications.

If you want a broader explanation of vitamin D, read Vitamin D Benefits: How It Supports Your Health.

When do vitamin D symptoms in a child need urgent care?

Most suspected vitamin D problems can be discussed with your child's pediatrician or family doctor.

A few signs need faster action because severe vitamin D deficiency can disturb calcium levels.

These symptoms do not prove vitamin D deficiency, but severe hypocalcemia, which means dangerously low blood calcium, can happen with severe vitamin D deficiency and requires medical care.

The Royal Children's Hospital guideline advises hospital assessment for children with symptomatic low calcium, including tetany, seizures, or severe rickets.

11 key symptoms of vitamin D deficiency in children

1. Bone pain or tenderness

Bone pain is one of the more useful symptoms to take seriously, especially if it lasts or affects how a child moves.

A child may complain about pain in the legs, pelvis, ribs, back, or other bones. Younger children may not be able to explain the pain clearly. Instead, they may become less active or avoid walking.

Do not assume every leg ache is vitamin D deficiency. Growing children can have pain for many reasons, including injury, infection, joint problems, overuse, and other bone conditions.

Persistent bone pain deserves medical assessment rather than a vitamin supplement chosen at home.

2. Muscle weakness or cramps

Vitamin D plays an important role in muscle as well as bone health.

Low vitamin D can be linked with muscle weakness, aches, or cramps. You may notice that a child tires more easily when walking, running, or climbing stairs.

Weakness is different from simply not wanting to exercise.

A child who suddenly loses strength, has trouble standing, or develops severe muscle symptoms needs medical assessment because many conditions can cause weakness.

3. Tiredness during normal activity

Some children with low vitamin D report tiredness or become tired more quickly during activity.

This is a very nonspecific symptom.

Fatigue can also happen with poor sleep, iron deficiency, infection, thyroid problems, stress, low calorie intake, chronic illness, or simply a demanding week.

So tiredness by itself is not a reason to diagnose vitamin D deficiency.

It becomes more useful when it appears with other risk factors or bone and muscle symptoms.

4. Delayed walking or other motor milestones

Severe deficiency in infants and young children can interfere with normal movement and development.

The Royal Children's Hospital lists poor growth and motor delay among possible presentations in infants.

A child may sit, stand, or walk later than expected, or a child who already walks may become reluctant to do so because movement hurts or muscles feel weak.

Many conditions can affect developmental milestones, so delayed walking should not automatically be blamed on vitamin D.

Discuss delayed motor development with a pediatric healthcare professional.

5. Poor growth

Vitamin D deficiency can affect healthy bone growth when it becomes severe enough to cause rickets.

A child may be smaller than expected or may not follow their normal growth pattern.

Doctors look at growth over time rather than one height measurement.

Delayed growth has many possible causes, including nutrition, genetics, hormone disorders, digestive conditions, chronic disease, and normal family growth patterns.

Vitamin D is one piece of that larger picture.

6. Bowed legs or knock knees

This is one of the classic signs of established rickets.

Soft growing bones can bend under body weight. This may lead to legs that curve outward or knees that angle inward more than expected.

Normal leg alignment changes as children grow, so parents should not try to diagnose rickets from the appearance of the legs alone.

A progressive change, pain, abnormal walking, or concern about a child's leg shape should be assessed by a healthcare professional.

7. Widened wrists or ankles

Rickets can cause widening around the ends of growing bones.

Parents may notice that the wrists or ankles look broader or swollen.

The Royal Children's Hospital includes widening of the wrists and ankles among examination findings that can occur with rickets.

This sign is much more meaningful than vague symptoms such as occasional tiredness.

8. Changes in walking

A child with painful or weak bones may walk differently.

The NHS lists changes in walking, reduced willingness to walk, and getting tired more easily while walking among possible rickets symptoms.

Children with significant muscle weakness can also develop a waddling style of walking or have trouble with stairs.

A new change in gait deserves medical attention, especially when it occurs with pain, weakness, or a bone deformity.

9. Delayed tooth eruption or dental problems

Severe vitamin D deficiency can affect teeth as well as bones.

NIH lists dental abnormalities among complications of severe rickets. Pediatric guidance also includes delayed dentition as a possible clue.

One late tooth does not diagnose vitamin D deficiency.

Children vary in the timing of tooth eruption, and genetics plays a large role.

Dental delay becomes more important when it appears with poor growth, bone changes, or other signs of rickets.

10. Fractures or unusually fragile bones

Severe problems with bone mineralization can weaken bone.

A fracture after a small injury, repeated fractures, or X ray findings that suggest weak bones may lead a clinician to investigate vitamin D, calcium, and other causes.

Vitamin D deficiency is not the only cause of fragile bones in children.

Doctors may need to consider nutrition, genetic bone disease, long term medicines, chronic illness, endocrine disorders, or other conditions.

For more on bone nutrients, visit the NextFitLife Bone and Joint Health Hub.

11. Muscle twitching, spasms, or seizures from low calcium

This is the serious end of the spectrum.

Vitamin D helps the gut absorb calcium. Severe deficiency can sometimes lead to low blood calcium.

Signs can include muscle cramps, twitching, spasms, tingling, tetany, or seizures.

Infants can also develop noisy breathing from a spasm around the airway.

These are not symptoms to watch at home.

Seek urgent medical care.

Which symptoms should parents not use to diagnose low vitamin D?

The older version of this article listed frequent illness, depression, anxiety, poor appetite, and respiratory problems as if they were dependable symptoms of vitamin D deficiency.

That is too strong.

Vitamin D has roles in immune and muscle function, and researchers study links between vitamin D status and many health outcomes. Association does not mean a symptom is specific enough to diagnose deficiency.

The 2024 Endocrine Society guideline points out that vitamin D blood levels have been associated with many conditions, but cause and effect has not been clearly established for many of them.

Which children are at higher risk of vitamin D deficiency?

Symptoms are only half of the story.

Risk factors tell a pediatrician whether vitamin D deserves a closer look.

Breastfed infants without vitamin D supplementation

Breast milk does not usually provide enough vitamin D by itself.

CDC guidance updated in July 2026 states that breastfed and partially breastfed infants who consume less than 32 ounces of formula per day need an additional source of vitamin D.

Children with darker skin

Melanin reduces the amount of vitamin D the skin makes from sunlight.

This does not mean darker skin is unhealthy.

It means skin pigmentation is one of several factors that can change vitamin D production and should be considered along with diet, location, clothing, and medical history.

Children with little sunlight exposure

Vitamin D production from sunlight varies with season, latitude, cloud cover, air pollution, clothing, skin pigmentation, time outdoors, and other factors.

This is why a fixed rule such as “ten minutes of sun” is not reliable for every child.

Children with digestive or absorption problems

Conditions that interfere with fat absorption can raise the risk because vitamin D is fat soluble.

Examples include celiac disease, Crohn disease, cystic fibrosis, and some other digestive disorders.

Children with kidney or liver disease

The liver and kidneys help process vitamin D into forms the body can use.

Chronic disease affecting these organs can change vitamin D metabolism.

Children with obesity

Children with obesity can have lower measured vitamin D concentrations and may require individualized medical advice.

Children taking certain medicines

Some medicines can affect vitamin D metabolism.

Examples include certain anticonvulsants and long term glucocorticoid treatment.

A parent should never stop a prescribed medicine because of vitamin D concerns. Ask the prescriber whether monitoring or supplementation is needed.

Premature infants or babies born to mothers with low vitamin D

Prematurity and maternal deficiency can increase risk during infancy.

Your baby's clinician can advise whether additional monitoring or supplementation is needed.

How much vitamin D do children need?

The amount depends on age.

Those values describe usual nutritional needs. They are not treatment doses for a diagnosed deficiency.

A child with proven deficiency or rickets may need a different dose chosen by a healthcare professional.

Do not use an adult high dose vitamin D product to treat a child unless a clinician specifically prescribed it.

What does the 2024 Endocrine Society guidance add?

The Endocrine Society updated its vitamin D guidance in 2024.

For children and adolescents aged 1 to 18, it suggests empiric vitamin D supplementation to help prevent nutritional rickets and potentially reduce respiratory infections.

There is an important limit.

The trials included many different doses, so the guideline does not provide one ideal higher dose that every child should take.

That is why the recommendation should not be read as permission to give high dose vitamin D without medical guidance.

The guideline also moved away from chasing one universal vitamin D blood target for preventing every possible disease.

This is a useful correction to older online articles that make exact numbers look more certain than they really are.

How do doctors test for vitamin D deficiency in children?

The main blood test is called 25 hydroxyvitamin D, often written as 25(OH)D.

This is the standard blood marker used to assess vitamin D status.

If a doctor suspects rickets or a more serious mineral problem, the workup can include other tests such as:

• Calcium
• Phosphate
• Alkaline phosphatase
• Parathyroid hormone
• Magnesium
• Kidney function tests
• Urine tests
• X rays when rickets is suspected

This helps answer a better question than “Is vitamin D low?”

Doctors want to know whether low vitamin D is affecting bone health, calcium balance, or another part of the child's body.

Should every child get a vitamin D blood test?

No.

Routine testing of every healthy child is not automatically useful.

Testing makes more sense when a child has symptoms, signs of rickets, abnormal bone tests, a condition that affects vitamin D absorption or metabolism, or other important risk factors.

The 2024 Endocrine Society guideline also emphasizes that widespread testing in healthy people has grown faster than evidence showing that routine screening improves outcomes.

Your child's clinician can decide whether a test is useful based on the whole picture.

What vitamin D blood level is normal for a child?

This question sounds simple, but the answer needs care.

Different organizations and laboratories have used somewhat different thresholds.

NIH notes that very low 25 hydroxyvitamin D levels are linked with deficiency and bone problems. However, the 2024 Endocrine Society guideline no longer endorses one universal target blood concentration for disease prevention in generally healthy people.

This is why I would not build a parent guide around a rigid table that labels every value as deficient, insufficient, perfect, or toxic without clinical context.

Your child's doctor should interpret the result with age, symptoms, diet, calcium status, medical conditions, and the laboratory range.

How is vitamin D deficiency treated in children?

Treatment depends on age, how low the vitamin D is, whether calcium is low, whether rickets is present, and why the deficiency happened.

A healthcare professional may recommend vitamin D supplementation and make sure the child gets enough calcium.

Children with clinical rickets or abnormal calcium often need specialist guidance.

Treatment should also address the cause.

If a child has celiac disease, kidney disease, liver disease, malabsorption, or a medication affecting vitamin D, simply giving a supplement may not solve the whole problem.

More vitamin D is not always better

Vitamin D is fat soluble. The body can store it.

Taking too much can cause vitamin D toxicity and raise calcium to harmful levels.

Highly concentrated drops are especially easy to misdose if a parent assumes every bottle contains the same amount per drop.

Check the label and use the exact product and dose recommended for your child.

Which foods contain vitamin D?

Vitamin D is naturally present in relatively few foods, which is one reason fortified foods matter.

Useful food sources can include:

• Salmon
• Trout
• Tuna
• Eggs
• Vitamin D fortified milk
• Fortified yogurt
• Fortified breakfast cereals
• Some fortified plant drinks
• Some fortified juices

Check food labels because fortification varies by country and product.

For practical meal ideas, see Foods High in Vitamin D and Vitamin D and Calcium Foods: 14 Smart Choices.

Children who avoid dairy can also get calcium from other foods. See Calcium Rich Foods Without Dairy.

Should parents use sunlight to treat low vitamin D?

Do not treat sunlight like a medicine with a fixed dose.

Vitamin D production in skin changes with season, latitude, skin pigmentation, cloud cover, air pollution, clothing, and other factors.

Ultraviolet radiation also damages skin.

CDC specifically recommends vitamin D supplementation for breastfed infants rather than trying to rely on a calculated amount of sunlight.

For older children, normal outdoor activity can be healthy, but sun safety still matters.

There is no one safe number of minutes that guarantees enough vitamin D for every child.

How can parents lower the risk of vitamin D deficiency?

Follow infant supplementation guidance

Breastfed and partially breastfed infants generally need 400 IU of vitamin D each day beginning shortly after birth.

CDC says formula fed infants who drink at least 32 ounces of vitamin D fortified infant formula per day usually do not need an additional vitamin D supplement.

Offer vitamin D foods as children grow

Use age appropriate foods that provide vitamin D, calcium, protein, and other nutrients needed for growth.

Know your child's risk factors

Tell the pediatrician about digestive disease, kidney or liver problems, prematurity, restrictive diets, medicines, or other factors that might affect vitamin D.

Do not self treat with high doses

Routine prevention and treatment of deficiency are not the same thing.

If a blood test shows deficiency, use the dose and schedule recommended by your child's healthcare professional.

Keep calcium in the picture

Vitamin D and calcium work together in growing bone.

A child with severe vitamin D deficiency and very low calcium intake has a different risk picture from a child with adequate calcium.

For more information, read Calcium Deficiency: Symptoms, Causes and Prevention.

Five mistakes parents should avoid

1. Waiting for obvious symptoms

A child can have low vitamin D without looking sick.

2. Assuming tiredness proves vitamin D deficiency

Fatigue has many causes. A blood test or medical evaluation may be needed when symptoms persist.

3. Treating frequent colds as a vitamin D test

Children get respiratory infections for many reasons. Repeated infections alone do not prove vitamin D deficiency.

4. Giving an adult supplement dose to a child

Vitamin D products vary widely in concentration. Too much can be harmful.

5. Forgetting calcium

Healthy bones need enough calcium as well as vitamin D.

Conclusion: Look at the child, not one vague symptom

The symptoms of vitamin D deficiency in children are often subtle, and many children have no obvious symptoms at all.

The signs that deserve the most attention involve bones, muscles, growth, movement, or calcium balance. Bone pain, muscle weakness, delayed walking, poor growth, bowed legs, widened wrists, gait changes, fractures, and severe muscle spasms all deserve proper assessment.

If your child has risk factors but seems well, discuss vitamin D at the next routine visit. If your child has persistent bone pain, weakness, growth problems, or signs of rickets, book a pediatric assessment sooner.

If seizures, severe spasms, or breathing problems occur, seek urgent medical care.

Your next step: check whether your child is receiving the recommended vitamin D for their age, then discuss any symptoms or risk factors with their healthcare professional rather than increasing the dose on your own.

References and Sources

1. National Institutes of Health, Office of Dietary Supplements. Vitamin D Fact Sheet for Health Professionals.
   Used for vitamin D function, recommended intake, deficiency, rickets, risk factors, blood testing, and toxicity.
   https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
2. Centers for Disease Control and Prevention. Vitamin D: Infant and Toddler Nutrition. Updated April 14, 2026.
   Used for infant and toddler requirements, formula feeding, supplementation, fortified foods, and rickets prevention.
   https://www.cdc.gov/infant-toddler-nutrition/vitamins-minerals/vitamin-d.html
3. Centers for Disease Control and Prevention. Vitamin D and Breastfeeding. Updated July 21, 2026.
   Used for breastfeeding supplementation, infant risk factors, and why sunlight should not replace infant supplementation guidance.
   https://www.cdc.gov/breastfeeding-special-circumstances/hcp/diet-micronutrients/vitamin-d.html
4. Endocrine Society. Vitamin D for the Prevention of Disease: Clinical Practice Guideline. 2024.
   Used for current guidance for children and adolescents, limits of routine blood testing, and uncertainty around universal target levels.
   https://www.endocrine.org/clinical-practice-guidelines/vitamin-d-for-prevention-of-disease
5. NHS. Rickets and Osteomalacia. Last reviewed July 9, 2025.
   Used for bone pain, bowed legs, walking changes, muscle weakness, fractures, and evaluation of suspected rickets.
   https://www.nhs.uk/conditions/rickets-and-osteomalacia/
6. Royal Children's Hospital Melbourne. Clinical Practice Guideline: Vitamin D Deficiency.
   Used for pediatric risk factors, poor growth, motor delay, delayed dentition, rickets signs, low calcium symptoms, testing, and specialist referral.
   https://www.rch.org.au/clinicalguide/guideline_index/Vitamin_D_deficiency/

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Frequently Asked Questions

What are the first symptoms of vitamin D deficiency in children?

There may be no obvious early symptoms. When symptoms occur, children can have bone pain, muscle weakness, cramps, or tiredness. More severe or long lasting deficiency can affect growth, movement, and bone shape.

How can I tell if my child has low vitamin D?

You cannot confirm vitamin D deficiency from symptoms alone. A healthcare professional may order a 25 hydroxyvitamin D blood test when a child has relevant symptoms, rickets signs, abnormal bone tests, medical conditions that increase risk, or other important risk factors.

Can vitamin D deficiency cause leg pain in children?

Yes. Bone or muscle pain can occur with vitamin D deficiency and rickets. Leg pain has many other causes, so persistent or severe pain should be assessed rather than treated with vitamin D without a diagnosis.

Can vitamin D deficiency delay walking?

Severe deficiency can contribute to muscle weakness, bone problems, and delayed motor milestones such as walking. Delayed walking has many possible causes, so a pediatric assessment is important.

Does low vitamin D cause frequent colds in children?

Vitamin D has a role in immune function, and research has studied vitamin D and respiratory infections. However, frequent colds are not a reliable way to diagnose vitamin D deficiency because children develop infections for many different reasons.

How much vitamin D does a child need each day?

Infants younger than 12 months generally need 400 IU, or 10 micrograms, per day. The standard dietary reference intake for children aged 1 year and older is 600 IU, or 15 micrograms, per day. Treatment doses for confirmed deficiency can be different and should be chosen by a healthcare professional.

Do breastfed babies need vitamin D drops?

CDC guidance says breastfed infants and partially breastfed infants who drink less than 32 ounces of vitamin D fortified formula per day need an additional source of vitamin D, usually 400 IU daily, beginning shortly after birth.

Should every child have a vitamin D blood test?

No. Routine testing of every healthy child is not usually necessary. Testing is more useful when symptoms, rickets signs, abnormal bone tests, medical conditions, medicines, or other risk factors make deficiency more likely.

Can too much vitamin D harm a child?

Yes. Excess vitamin D from supplements can cause toxicity and dangerously high calcium levels. Never use high dose vitamin D or an adult treatment schedule for a child unless a qualified healthcare professional has prescribed it.

Can a child get enough vitamin D from sunlight alone?

There is no fixed amount of sunlight that guarantees enough vitamin D for every child. Vitamin D production changes with season, location, skin pigmentation, clothing, pollution, and other factors. Infants who need supplementation should not rely on sunlight instead.

When should I worry about vitamin D deficiency in my child?

Arrange medical assessment if your child has persistent bone pain, muscle weakness, poor growth, delayed walking, changes in leg shape, widened wrists or ankles, unusual fractures, or important risk factors. Seizures, severe muscle spasms, or breathing difficulty need urgent medical care.