# Vitamin D deficiency symptoms: the signs, the blood levels and what to do next

Low vitamin D often has no symptoms at all, and the ones it does cause are easy to blame on something else. Here’s which signs are well proven, which are only linked, and how a simple blood test settles it.

Source: https://nourishandstrong.com/vitamin-d-deficiency-symptoms
Published: 2026-11-08
Updated: 2026-11-08
By: the Nourish & Strong team
General information, not medical advice.

**The short answer:** the clearest symptoms of vitamin D deficiency are bone pain and muscle weakness. Cleveland Clinic also lists fatigue, muscle aches or cramps and mood changes such as depression, though many people have no symptoms at all. Only a blood test can confirm it. The NIH says a level below 12 ng/mL (30 nmol/L) is too low.

Vitamin D helps your body absorb calcium. When you run short for a long time, your blood calcium drops, and your body pulls calcium out of your bones to make up for it, Cleveland Clinic explains. That’s where most of the symptoms come from.

## What are the symptoms of vitamin D deficiency?

The symptoms of vitamin D deficiency in adults are mostly in the bones and muscles. Some are well proven, while others are only linked. Here’s how strong the evidence is for each:

| Symptom | What the sources say | Evidence strength |
| --- | --- | --- |
| Bone pain | NIH says deficiency causes osteomalacia, with bone pain. The NHS lists pain in the back, shoulders, ribs, pelvis or legs. | Strong |
| Muscle weakness | NIH and the NHS both list it. The NHS describes trouble climbing stairs or getting out of a chair. | Strong |
| Muscle aches, cramps or twitching | Cleveland Clinic lists aches and cramps. The NHS adds tingling and twitching. | Moderate |
| Bones that break easily | The NHS lists breaks after a minor accident, especially hips, lower back and feet. | Strong, in long-term deficiency |
| Fatigue | Cleveland Clinic lists it as a possible sign. The NHS mentions tiring more easily when walking. | Possible, not specific |
| Low mood or depression | Cleveland Clinic lists mood changes. NIH says low levels are linked with depression, but supplements haven’t prevented or eased it in trials. | Linked, not proven to be caused |

In children, the main sign is rickets: bowed legs, painful wrists, slow growth and late teeth, the NHS says.

## Can vitamin D deficiency cause fatigue?

Vitamin D deficiency can cause fatigue, but tiredness alone is a poor clue. Cleveland Clinic lists fatigue among possible signs in adults, and explains that very low calcium in the blood from severe deficiency can cause fatigue and depression. Tiredness has many other causes, though, and our guide to [why you’re always tired](https://nourishandstrong.com/why-am-i-always-tired) walks through them. If you’re tired and also have aching bones or weak muscles, low vitamin D becomes a more likely suspect.

## Can vitamin D deficiency cause anxiety or depression?

The link is real, but cause and effect isn’t proven. The NIH says some studies have found low vitamin D levels linked with a higher risk of depression. Yet clinical trials show vitamin D supplements don’t prevent depression or ease its symptoms. We found no strong evidence on anxiety. If your mood has been low for more than a couple of weeks, talk to your doctor, whatever your vitamin D level.

## What vitamin D level is too low?

A vitamin D level below 12 ng/mL (30 nmol/L) is too low, according to the NIH. The test measures 25-hydroxyvitamin D, and labs report it in ng/mL or nmol/L. Here are the NIH cutoffs, with the labels MedlinePlus says your report may use:

| Blood level of 25(OH)D | What the NIH says | Label your report may use |
| --- | --- | --- |
| Below 12 ng/mL (30 nmol/L) | Too low; might weaken bones and affect health | Deficient |
| 12 to 20 ng/mL (30 to 50 nmol/L) | Below the level NIH calls adequate for most people | Insufficient |
| 20 ng/mL (50 nmol/L) or above | Adequate for most people for bone and overall health | Sufficient |
| Above 50 ng/mL (125 nmol/L) | Too high; might cause health problems | Possible toxicity |
| Above 150 ng/mL (375 nmol/L) | Can cause nausea, vomiting, confusion and kidney stones | Toxic |

To convert, 1 nmol/L equals 0.4 ng/mL. The NIH notes that experts haven’t settled on exact cutoffs, so ask how your lab defines its ranges.

## Who is most at risk of vitamin D deficiency?

People who get little sun on their skin are most at risk, along with people whose bodies struggle to absorb or use vitamin D. The NIH says almost 1 in 4 people in the US have levels that are too low or inadequate. Our guide to [how to get vitamin D](https://nourishandstrong.com/how-to-get-vitamin-d) covers the sun and food side. These are the main risk groups, with the reason for each:

| Who | Why |
| --- | --- |
| People who rarely go outside or cover most of their skin | Less sunlight reaches the skin to make vitamin D |
| People with darker skin | More melanin means less vitamin D made from the same sun |
| Older adults | The skin makes less vitamin D with age |
| People with Crohn’s, celiac disease, ulcerative colitis or cystic fibrosis | The gut absorbs less vitamin D |
| People with kidney or liver disease | These organs turn vitamin D into its working form |
| People with obesity or who’ve had gastric bypass surgery | Fat tissue holds on to vitamin D, and surgery cuts absorption |
| Vegans, and people with a milk allergy or lactose intolerance | Fortified foods such as milk provide most of the vitamin D in US diets |
| People taking some medicines | Cleveland Clinic lists steroids such as prednisone, some seizure drugs, rifampin, orlistat, some cholesterol drugs and laxatives |
| Breastfed babies | Breast milk alone doesn’t provide enough |

Sources: the NIH Office of Dietary Supplements, Cleveland Clinic and MedlinePlus. If you take any of those medicines, ask your doctor whether a test makes sense.

## How do you test for vitamin D deficiency?

A simple blood test checks for vitamin D deficiency. It measures 25-hydroxyvitamin D from a sample taken from a vein in your arm, and you don’t need to do anything to prepare, MedlinePlus says. Tell your provider about all your supplements and medicines, since they can affect the result.

Routine testing for everyone isn’t advised. The US Preventive Services Task Force says there isn’t enough evidence to weigh the benefits and harms of screening adults with no symptoms. Cleveland Clinic says doctors usually test people with symptoms, risk factors or conditions such as low bone density.

## What happens if vitamin D deficiency is left untreated?

Left untreated, long-term vitamin D deficiency softens the bones. In adults this is osteomalacia, which causes bone pain and muscle weakness, the NIH says. In children it’s rickets, where bones become soft, weak, misshapen and painful. Cleveland Clinic adds low blood calcium and phosphate to the complications, and says untreated severe rickets can lead to seizures, heart damage and death. Low vitamin D and calcium over many years also make bones fragile in osteoporosis.

**See a doctor if you have:**

- bone pain in your back, hips, ribs or legs that doesn’t settle
- muscles so weak that stairs or getting out of a chair is hard
- a bone that broke after a minor fall
- a child with bowed legs, painful wrists or slow growth

## How is vitamin D deficiency treated?

Vitamin D deficiency is usually treated with supplements your doctor recommends. Cleveland Clinic says the goal is to reach and then keep an adequate level, and that D3 is absorbed more easily than D2. The NIH says your doctor may suggest more than the usual upper limit of 4,000 IU (100 mcg) a day for a short time to correct a deficiency. Don’t do that on your own, because too much can raise blood calcium and harm your kidneys and heart. Your doctor may retest to check your level is rising.

Two things help alongside: food and safe sun, both covered in our guide to [vitamin D foods](https://nourishandstrong.com/how-to-get-vitamin-d#foods), and enough calcium. Our guide to [calcium supplements](https://nourishandstrong.com/calcium-supplements) explains how much you need. Magnesium helps your body activate vitamin D, and our comparison of [which magnesium is best](https://nourishandstrong.com/which-magnesium-is-best) shows how to get it.

## Your next step

Check yourself against the risk table above. If you’re in one of those groups and have bone pain, weak muscles or a recent easy fracture, book a blood test and bring your list of medicines and supplements. If you have no symptoms, work on the basics first: the [free 7-day meal plan](https://nourishandstrong.com/free-plan) is an easy way to build more vitamin D and calcium foods into your week.

## Quick questions

### Can vitamin D deficiency cause hair loss?

There’s no good evidence that vitamin D deficiency causes hair loss. None of the sources we checked, including the NIH, the NHS and Cleveland Clinic, list hair loss as a symptom. Thinning hair has other possible causes, so a vitamin D supplement is unlikely to be the fix on its own. If you’re losing hair, ask your doctor to look for the cause.

### Is vitamin D deficiency serious?

Vitamin D deficiency can be serious if it lasts. Over time it softens the bones, causing osteomalacia in adults and rickets in children, with bone pain, muscle weakness and fractures. It’s treatable, though. Cleveland Clinic says the aim is to reach and keep an adequate level, usually with supplements your doctor recommends.

### What vitamin D level is too high?

A vitamin D level above 50 ng/mL (125 nmol/L) is too high and might cause health problems, the NIH says. Above 150 ng/mL (375 nmol/L) can cause nausea, vomiting, muscle weakness, confusion and kidney stones. Too much almost always comes from supplements. Your skin limits how much vitamin D it makes from the sun.

### Does vitamin D deficiency cause joint pain?

Vitamin D deficiency mainly causes bone pain, which can feel like joint pain. The NHS lists swollen, painful wrists and pain in the back, shoulders, ribs, pelvis or legs as signs of osteomalacia. Joint pain has many other causes too. See your doctor if pain lasts or comes with muscle weakness.

### Is vitamin D deficiency common?

Low vitamin D is fairly common. The NIH says almost 1 in 4 people in the US have blood levels that are too low or inadequate for bone and overall health, though most people have enough. It’s more common in people who get little sun, have darker skin, are older or have gut, kidney or liver conditions.

### Can vitamin D deficiency cause weight gain?

There’s no evidence that low vitamin D causes weight gain. The NIH says higher body weight is linked with lower vitamin D levels, and Cleveland Clinic says fat cells keep vitamin D locked away. But research doesn’t support vitamin D supplements or vitamin D-rich foods for weight loss. A blood test is the only way to know your level.

This article is general information, not medical advice. Only a blood test can show whether your vitamin D is low, and your doctor can tell you how to treat it. Don’t take high-dose vitamin D without medical advice, and don’t stop or change any prescribed medicine on your own.

## Sources

- [NIH Office of Dietary Supplements. Vitamin D: Fact Sheet for Consumers](https://ods.od.nih.gov/factsheets/VitaminD-Consumer/)
- [NIH Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/)
- [Cleveland Clinic. Vitamin D Deficiency](https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency)
- [NHS. Rickets and osteomalacia](https://www.nhs.uk/conditions/rickets-and-osteomalacia/)
- [NHS. Vitamin D](https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/)
- [MedlinePlus. Vitamin D Test](https://medlineplus.gov/lab-tests/vitamin-d-test/)
- [US Preventive Services Task Force. Vitamin D Deficiency in Adults: Screening](https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/vitamin-d-deficiency-screening)
- [Harvard T.H. Chan School of Public Health, The Nutrition Source. Magnesium](https://nutritionsource.hsph.harvard.edu/magnesium/)