Vitamin D Deficiency Symptoms: Signs, Who's at Risk and When to See a GP

Most people with low vitamin D have no symptoms at all. When symptoms do appear they are often vague, such as general aches, and severe, long-lasting deficiency can cause bone pain, muscle weakness and soft bones (osteomalacia in adults, rickets in children). In the UK, low vitamin D is common in winter, so the NHS advises everyone to consider a daily 10 microgram supplement from autumn to spring. See your GP if you have ongoing bone pain, muscle weakness or a fracture after a minor fall.

What are the symptoms of vitamin D deficiency?

Often there are no symptoms. When there are, they tend to be vague at first (such as general muscle aches) and only become specific to bone and muscle when deficiency is severe and long-lasting. NHS South West London guidance for GPs separates people at risk who have no symptoms from people with symptoms that could be due to deficiency, and advises against routine testing unless there are symptoms NHS South West London, 2023.

Vitamin D helps regulate calcium and phosphate in the body NHS. Without enough of it, bone can't mineralise properly. That is why the symptoms that point most clearly to deficiency are bone and muscle symptoms:

• Bone pain and tenderness that comes on gradually, especially in the lower back and hips, but also the ribs, thighs or feet.
• Muscle weakness, particularly in the large muscles near the hips and shoulders (proximal muscle weakness). It can make it harder to climb stairs or get up from a chair.
• Fractures from minor falls or knocks.
• General muscle aches with no other obvious cause.

These features are listed in NHS clinical guidance as symptoms that justify testing NHS South West London, 2023. The same guidance notes that low vitamin D has been linked with other conditions, including mental health problems, but that the evidence is "inconsistent, conflicting, or absent", so it is not certain that correcting vitamin D improves them. Be wary of online symptom lists that blame hair loss, low mood or frequent colds on vitamin D alone.

What is osteomalacia, and what are the signs in adults?

Osteomalacia means "soft bones". It is the adult form of severe vitamin D (and calcium) deficiency, where new bone isn't properly hardened with minerals. The NHS lists the symptoms in adults as NHS:

• swollen, painful wrists
• pain in the back, shoulders, ribs, pelvis or legs
• changes in the way you walk, or getting tired more easily when walking
• difficulty climbing stairs or getting out of a chair because of weak muscles
• tingling, cramping or twitching of the muscles
• breaking bones more often or after a minor accident, especially the hips, lower back and feet

The NHS says rickets and osteomalacia are "usually caused by low levels of vitamin D and calcium in your body" NHS. In the UK that often comes from too little sunlight between October and March, combined with a diet low in calcium.

Osteomalacia is different from osteoporosis. In osteoporosis, bone is properly mineralised but there is less of it. In osteomalacia, the bone itself is soft. They can overlap, and both raise fracture risk, which is why vitamin D status is checked before some osteoporosis treatments. If you are unsure which is which, our guide to signs of osteoporosis explains why osteoporosis usually has no warning signs until a bone breaks.

What are the signs of vitamin D deficiency in children?

In children, severe deficiency causes rickets, and the main sign is bowed legs. The NHS adds that children with rickets may be short for their age, and their teeth may come through later than usual NHS. See a GP if you think your child might have rickets.

The NHS advises a daily vitamin D supplement of 8.5 to 10 micrograms for breastfed babies (and formula-fed babies having less than 500ml of formula a day), and 10 micrograms for children aged 1 to 4 NHS.

Who is most at risk of low vitamin D in the UK?

Anyone in the UK can run low in winter, but the risk is highest for people who get little sun on their skin or who absorb or process vitamin D poorly. From about late March or early April to the end of September, most people can make enough vitamin D from sunlight. Outside those months, they can't NHS. NHS guidance lists these higher-risk groups NHS South West London, 2023:

• Adults aged 65 and over
• People who are rarely outdoors, such as housebound people or care home residents
• People who cover most of their skin when outside
• People with dark skin, including those of African, African-Caribbean and South Asian family origin
• Pregnant and breastfeeding women, and children under 5

Other things can raise your risk too NHS South West London, 2023:

• a vegan or strict vegetarian diet
• obesity
• conditions that affect absorption, such as coeliac disease, Crohn's disease, cystic fibrosis, or having had bariatric surgery
• chronic liver or kidney disease
• some medicines, including certain anti-epileptic drugs, rifampicin, long-term corticosteroids (3 months or more) and orlistat

If any of these apply, our guides on coeliac disease and bone health, steroids and bone loss and bone health for vegans and vegetarians go into more detail.

How is vitamin D deficiency diagnosed?

It is diagnosed with a blood test for 25-hydroxyvitamin D. A level below 25 nmol/L counts as deficiency, but most people don't need the test. NHS guidance based on the Scientific Advisory Committee on Nutrition (SACN) and the Royal Osteoporosis Society uses these thresholds NHS South West London, 2023:

Blood level (25-hydroxyvitamin D)	What it means
Below 25 nmol/L	Vitamin D deficiency
25–50 nmol/L	May be insufficient for some people
Above 50 nmol/L	Sufficient for most people

Routine testing is not recommended for the general population, or even for higher-risk groups, unless you have symptoms NHS South West London, 2023. The Royal Osteoporosis Society agrees: "You do not normally need a blood test to check if you are getting enough vitamin D." It notes that you will often have a test if you are starting the osteoporosis medicines zoledronate or denosumab Royal Osteoporosis Society.

If osteomalacia is suspected, a GP will usually check vitamin D and calcium with blood tests and a urine sample, and may refer you for X-rays or bone scans NHS.

How do you prevent or treat low vitamin D?

For prevention, the NHS advises everyone to consider 10 micrograms (400 IU) of vitamin D a day in autumn and winter, and all year round if you are in a higher-risk group. The all-year groups are people who are not often outdoors, people in care homes, people who usually cover most of their skin outdoors, and people with dark skin NHS. Vitamin D supplements are cheap and available without a prescription.

Confirmed deficiency is different. Your GP will prescribe a treatment course, often a higher "loading" dose followed by a maintenance dose, and the exact regimen depends on your blood level and health. Don't self-treat with high doses, and don't take more than 100 micrograms (4,000 IU) a day unless a doctor tells you to NHS. UK osteoporosis guidance also warns against routine very large intermittent doses (for example 60,000 IU or more), which have been linked to more falls and fractures NOGG, 2024.

For the full detail on doses, including what's advised if you have osteoporosis, see our guide to vitamin D for bone health. Vitamin D also needs enough calcium to work with, so it's worth checking your diet against our calcium-rich foods chart and our guide to vitamin D, calcium and protein.

When should you see a GP?

See your GP if you have symptoms that could point to deficiency or soft bones, especially if you are in a higher-risk group. Make an appointment if you have:

• bone pain or tenderness that doesn't go away, particularly in the lower back, hips, pelvis or legs
• muscle weakness, such as struggling to get up from a chair or climb stairs
• a fracture after a minor fall or knock
• signs of rickets in a child, such as bowed legs

Can low vitamin D affect your bone density?

Yes. Vitamin D helps your body manage calcium and phosphate, so a long-term shortfall can weaken bone and raise fracture risk. Osteomalacia is the extreme end, but milder, long-lasting shortfalls also matter for anyone at risk of osteoporosis. That is why the Royal Osteoporosis Society says your doctor may suggest a higher daily dose, such as 20 micrograms, if you are at risk of osteoporosis or taking an osteoporosis medicine Royal Osteoporosis Society.

Correcting vitamin D won't show you how strong your bones are. If you have risk factors, ask your GP about a fracture risk assessment and, if needed, a DEXA scan, which is the UK standard for diagnosing osteoporosis. If you would like a radiation-free baseline to track over time, Screen My Bones offers a bone health assessment using REMS ultrasound at the spine and hip. It is for screening and monitoring, not a replacement for a DEXA scan when a diagnosis is needed.

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This article is part of our nutrition and supplements series.