Vitamin D deficiency symptoms you can easily miss, and the winter advice

In the UK, between October and early March the sun is too weak for the skin to make enough vitamin D. A shortfall builds slowly, and its first signs look like the aches most people put down to a bad back or a long week. This article lists those signs, who is most at risk, what the NHS advises for autumn and winter, and how to compare vitamin D prices once you know what dose you are looking for.

The advice quoted here comes from the NHS in the UK. This blog also serves readers in South Africa, where the seasons and the sunlight are different; that part has its own section below.

What vitamin D does

Vitamin D helps the body regulate calcium and phosphate, which bones, teeth and muscles need. Most of it is made in the skin in sunlight; food supplies only a small part. That is why the season matters more than the menu.

Symptoms of vitamin D deficiency

A long-term lack of vitamin D can cause rickets in children and a condition called osteomalacia in adults, in which the bones soften and hurt. The NHS lists these signs of osteomalacia in adults:

• 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 a bone more often, or after a minor accident.

Each of these has other, more common causes, which is why low vitamin D is easy to miss. If several of them fit, tell your doctor; only a blood test shows your vitamin D level, and the doctor decides whether you need one.

Who is most at risk

The NHS names groups who may not make enough vitamin D even in summer and should consider a supplement all year round:

• people who are rarely outdoors, for example because they are frail or housebound;
• people with dark skin, who make less vitamin D from the same sunlight;
• children aged 1 to 4, and babies, who have their own advice (below).

The UK advice on vitamin D in winter

The government advice in the UK is that everyone should consider taking a daily vitamin D supplement during autumn and winter. The amounts are:

• Adults and children from 1 year: 10 micrograms a day.
• Children aged 1 to 4: 10 micrograms a day all year round.
• Babies: breastfed babies, and babies having less than 500 ml of formula a day, 8.5 to 10 micrograms a day all year round.

From about late March or early April to the end of September, most people can make all the vitamin D they need from sunlight.

How much is too much

The NHS says adults should not take more than 100 micrograms (4,000 IU) a day. Taking too much over a long time can raise the calcium level in the blood (hypercalcaemia), which can weaken the bones and damage the kidneys and the heart. Some medical conditions mean a person cannot safely take as much; if that might be you, ask your doctor first.

Micrograms and IU on the label

Packs give the dose in micrograms (mcg or µg), in international units (IU), or both. One microgram is 40 IU, so the 10 microgram daily amount is 400 IU and the 100 microgram limit is 4,000 IU. Check this before you compare two products, because a 25 microgram tablet is not the same as a 10 microgram one.

Vitamin D in South Africa

The October-to-March advice is written for British sunlight. In South Africa the seasons run the other way and the sun is higher in the sky, so the UK calendar does not carry over. The symptoms above are the same everywhere; whether you need a supplement, and in which months, is a question for your pharmacist or doctor.

Vitamin D from food

The NHS lists oily fish (salmon, sardines, herring, trout, mackerel), red meat, egg yolks, liver and fortified foods such as some fat spreads and breakfast cereals. In the UK, cows' milk is generally not fortified, so it is not a good source. Food helps, but in winter it rarely covers the daily amount on its own, which is why the advice is a supplement.

How to compare vitamin D prices

The NHS notes that vitamin D supplements are sold in most pharmacies and supermarkets. The price on the shelf says little until you divide it into daily doses:

• Compare the same dose. Put 10 microgram products next to 10 microgram products.
• Divide by the number of tablets or capsules to get the price of one day. A winter, October to March, is about 180 days.
• Compare the whole basket with delivery. Vitamin D is a small, cheap item; on its own, the delivery charge can cost more than the tablets. Added to the rest of your winter basket, it travels in the same parcel.

Our cheap vitamin D page compares vitamin D prices per capsule. CheaperForDrug is a price comparison, not a pharmacy: comparing is free, with no account and no limit, and prices are checked at the moment you compare. Read about the cheapest online pharmacy for your basket to see why the result depends on everything in it.

Add vitamin D to your winter basket and compare the total with delivery.

Sources

• NHS: Vitamin D
• NHS: Rickets and osteomalacia, symptoms (page reviewed 9 July 2025)

Updated 10 October 2026. This article is general information, not medical advice. Ask a pharmacist or doctor before taking a supplement, especially if you take other medicines, are pregnant or have a kidney condition.