Magnesium for Kids: How Much They Need, Best Foods and Supplements (UK)

How much magnesium do children need?

These are the UK reference nutrient intakes (RNIs), set by the Department of Health in 1991 and still used today. The RNI is the amount that meets the needs of nearly all children (97.5%) in each age group, from all sources, mainly food:

The figures are the same for boys and girls up to 18. Babies get what they need from breast milk or formula. These are daily needs from the whole diet, not a supplement dose: a child eating normally is likely to be getting most or all of this already. For adult needs, see magnesium for women.

How much magnesium is safe for a child?

Magnesium naturally present in food isn’t counted towards upper limits. The risk comes from supplements and medicines containing magnesium, where too much can cause diarrhoea, feeling sick and stomach cramps.

The UK hasn’t set an upper limit for supplemental magnesium in children. The European Food Safety Authority (EFSA) has: no more than 250mg a day from supplements for anyone aged 4 and over, including adults. It didn’t set a figure for children aged 1 to 3, because there wasn’t enough data. This limit is for magnesium from supplements, fortified foods and water, on top of food.

An upper limit is a ceiling, not a target. A children’s product designed for their age will usually give much less than this. Adult supplements are dosed for adults, which is why you shouldn’t share your own with a child. Children with kidney problems should only take magnesium on a doctor’s advice. More on adult side effects in magnesium side effects.

Best magnesium foods for kids

A day of porridge, a wholemeal sandwich with peanut butter, a banana, beans on toast and a glass of milk covers a younger child’s needs comfortably. Swapping white bread, pasta and rice for wholegrain versions is one of the easiest ways to add magnesium for the whole family. For more ideas and amounts, see foods high in magnesium.

Why children need magnesium

Magnesium is an essential mineral involved in hundreds of processes in the body. It contributes to the maintenance of normal bones, normal muscle function, normal functioning of the nervous system, normal energy-yielding metabolism and normal psychological function. Children need more as they grow, which is why the amounts step up through childhood and into the teens.

Signs of low magnesium in children

True magnesium deficiency is uncommon in healthy children. When it happens, it’s usually linked to a medical condition such as long-term diarrhoea, coeliac or Crohn’s disease, kidney problems, type 1 diabetes or certain medicines. Possible signs include tiredness, weakness, muscle cramps or twitches, poor appetite and feeling sick.

These signs are very general and have many other causes, so don’t guess. If you’re worried, see your GP, who can look at your child’s diet and arrange tests if needed. Children on very restricted diets, such as some autistic children or very fussy eaters, may benefit from a review with a dietitian. Our guide to signs of magnesium deficiency covers adults in more detail.

Does magnesium help children sleep?

This is the most common reason parents search for magnesium, and the honest answer is that we don’t know. There are no good-quality trials of magnesium supplements for sleep in healthy children. The research on magnesium and sleep has mostly been in adults, often older adults, and the results are mixed; see magnesium for sleep for what those studies found.

Many kids’ sleep sprays, lotions, drops and gummies are sold on the idea, but the evidence hasn’t caught up with the marketing. If your child is low in magnesium because of a medical condition or a very limited diet, correcting that with your GP’s help makes sense. For most children who struggle to settle, a steady routine, less screen time and dealing with worries do far more (see better ways to help children sleep).

iSee your GP if your child’s sleep problems carry on or are affecting their days.

Magnesium and ADHD: what the research says

Magnesium isn’t a treatment for ADHD, autism or anxiety in children. If your child has these difficulties, speak to your GP, who can refer you for assessment and support, and talk to your child’s specialist before adding any supplement, especially if they take medication. CBD isn’t an option either: the FSA doesn’t recommend CBD products for under-18s unless under medical direction (see CBD for kids and CBD for ADHD).

Magnesium for children’s constipation

Some forms of magnesium, such as magnesium hydroxide and oxide, work as laxatives by drawing water into the bowel. That’s why parents search for magnesium for kids’ constipation. But constipation in children should be checked by a GP first, rather than treated with shop-bought supplements.

The NHS advises plenty to drink and a variety of foods including plenty of fruit and vegetables, and says laxatives are often recommended for children who are eating solid foods, alongside diet and lifestyle changes. Treatment can take several months. A 2025 review of 59 trials in children found that polyethylene glycol (also called macrogol) was probably more effective than other options and should be the standard first choice. Magnesium oxide or hydroxide was tested in 7 of those trials.

So don’t give a child magnesium as a laxative unless your GP or pharmacist suggests it, and take your child to a GP if you think they’re constipated: the NHS says getting help early matters, as constipation gets harder to resolve the longer it lasts. More on how magnesium affects the bowel in adults in magnesium for constipation.

Should children take magnesium supplements?

Usually not. The NHS recommends vitamin supplements containing vitamins A, C and D for children aged 6 months to 5 years, and vitamin D in autumn and winter for older children, but magnesium isn’t routinely recommended. A GP might suggest it if a child has a diagnosed deficiency, a restricted diet or a medical condition affecting absorption.

The NHS also warns that having too much of some vitamins can be harmful and advises talking to a pharmacist about which supplement suits your child. If you’re giving a multivitamin already, check whether it contains magnesium before adding more. For the vitamin D side, see vitamin D in winter and magnesium and vitamin D.

Choosing a children’s magnesium supplement

• Only use products made for your child’s age, and follow the label dose exactly. Don’t give adult supplements, which can contain far more magnesium and added herbs.
• Choose a gentle form such as citrate or glycinate; too much of any form can cause diarrhoea and stomach ache. See glycinate vs citrate vs threonate.
• Liquids and powders are often easier for young children to take than tablets.
• Watch the sugar in gummies and keep them out of reach, as they look like sweets. See are magnesium gummies safe for kids?
• Count every source: add up magnesium from multivitamins, gummies and any other products so the total from supplements stays well within the limits above.
• Check medicines: magnesium can affect some antibiotics, so ask your pharmacist about timing.
• Avoid them if your child has kidney problems, unless a doctor advises otherwise.

Evopure’s magnesium products are made for adults and aren’t suitable for children. Learn more about the different forms in types of magnesium.

Magnesium spray and baths for children

Magnesium sprays and lotions are often marketed for children’s sleep and “growing pains”. There’s no good evidence that useful amounts of magnesium are absorbed through the skin, so any benefit is likely to come from the calming bedtime massage or warm bath itself. Sprays often sting, especially on dry or broken skin, and children’s skin is more sensitive. Ask a pharmacist before using one on a child. See does magnesium spray work?

Better ways to help children sleep

1. A consistent bedtime and wake time, including at weekends where possible.
2. A calm 30 to 60 minute routine: bath, pyjamas, teeth, story, lights out.
3. Screens off at least an hour before bed, and out of the bedroom.
4. A cool, dark, quiet room.
5. Daylight and active play during the day.
6. No caffeine: watch out for cola, energy drinks and chocolate in the evening.
7. Time to talk about worries earlier in the evening, not at lights out.

Most of these work for adults too; see sleep hygiene. Melatonin is prescription-only in the UK, including for children. See melatonin in the UK.

See also how much magnesium per day adults need, and how to read supplement labels.

Looking at a specific product? Our Novomins magnesium guide sets out what the Kids gummy contains.