Last updated: October 2026
Early signs of low magnesium include tiredness, muscle cramps or twitches, weakness, poor appetite and feeling sick. More severe deficiency can cause numbness, tingling and an irregular heartbeat, which needs urgent medical care. True deficiency is uncommon in healthy people eating a varied diet, and is more likely with long-term acid-reducing medicines, diuretics, heavy drinking or gut conditions.
Below: signs to watch for, who’s most at risk, how it’s tested, what to do, and food sources.
Signs of magnesium deficiency
| Stage | Possible signs |
|---|---|
| Early or mild | Tiredness, weakness, loss of appetite, feeling sick, muscle cramps, eyelid twitches |
| More severe | Numbness or tingling, muscle spasms, tremors, irregular or fast heartbeat, low calcium or potassium levels, seizures |
These signs are common and have many causes, including poor sleep, stress, low iron or B12, and thyroid problems, so they don’t prove you’re low in magnesium. Get a racing or irregular heartbeat, fainting or seizures checked urgently: call 111, or 999 in an emergency.
Our pick
Magnesium Glycinate Sleep Complex
Magnesium Glycinate Sleep Complex is a berry drink powder with 290mg of magnesium a scoop from bisglycinate and citrate, plus glycine and L-theanine. Magnesium contributes to a reduction of tiredness and fatigue.
Add Magnesium Glycinate Sleep Complex to bag See ingredients and reviews
Vegan and made in the UK. Free UK delivery over £45, 14-day returns on unopened items.
Subscribe £22.49One-off £29.99
View productWho’s most at risk?
| Risk factor | Why |
|---|---|
| Long-term proton pump inhibitors (such as omeprazole) | The MHRA warns they can cause low magnesium, usually after a year or more |
| Diuretics (water tablets) | Increase magnesium loss in urine |
| Heavy drinking | Reduces absorption and increases losses |
| Gut conditions such as Crohn’s or coeliac disease, or long-lasting diarrhoea | Reduce absorption |
| Type 2 diabetes | Higher losses in urine |
| Older age | Lower intake and absorption |
| Low intake of whole foods | Diets low in nuts, seeds, greens and wholegrains |
How is low magnesium tested?
Your GP can check magnesium with a blood test. Only about 1% of the body’s magnesium is in the blood, so a normal result doesn’t always rule out low stores, but a low result is meaningful. Doctors usually check it alongside calcium and potassium, especially if you take medicines that lower magnesium.
What to do if you think you’re low
- Eat more magnesium-rich foods first (see below).
- Ask your GP for a blood test if you have symptoms or a risk factor.
- Consider a supplement: the NHS says 400mg a day or less from supplements is unlikely to cause harm. Glycinate and citrate are well absorbed. See best magnesium supplement UK.
- Give it time: see how long magnesium takes to work.
Magnesium contributes to a reduction of tiredness and fatigue, normal muscle function and normal psychological function. Severe deficiency is treated by doctors, sometimes with magnesium through a drip. Don’t take supplements if you have kidney disease unless advised. For other reasons you might feel drained, see why am I always tired?
Our Magnesium Glycinate Sleep Complex gives 290mg of magnesium per serving from bisglycinate and citrate, as an evening drink. We don’t recommend our products during pregnancy or breastfeeding.
The FSA’s 10mg a day figure for CBD is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.
Foods high in magnesium
| Food group | Examples |
|---|---|
| Nuts and seeds | Pumpkin seeds, almonds, cashews |
| Leafy greens | Spinach, kale |
| Wholegrains | Wholemeal bread, oats, brown rice |
| Beans and pulses | Black beans, chickpeas, lentils |
| Other | Dark chocolate, bananas, avocado |
The NHS says adults need 300mg (men) or 270mg (women) a day, and most people can get this from a varied diet. See magnesium for cramps and magnesium for sleep.
Related guides
- Signs of low magnesium in children.
- Magnesium taurate, a gentle but less studied form.
- Eye twitching: is it low magnesium or something else?
- How much magnesium and calcium you need.
- Twitching is usually down to stress, caffeine or tiredness rather than low magnesium; see common causes of muscle twitching.
- Pumpkin seeds benefits and how many to eat a day.
- Is restless legs caused by low magnesium?
- For how low magnesium compares with low zinc, see magnesium vs zinc.
- Are people with PCOS low in magnesium?
- Why magnesium spray isn’t a reliable way to top up.
- About 1 in 5 men aged 19 to 64 eat less than the minimum, which is why we’ve written a separate guide to how much magnesium a man should take.
- The simplest first step is food: see our list of foods high in magnesium, with amounts per UK portion.
- A blood test is the usual check; see the normal magnesium range in a UK blood test.
- To raise your intake, the form matters: our magnesium glycinate vs citrate vs threonate comparison shows how much magnesium each one gives.
- If you decide to top up, magnesium glycinate is one of the gentlest forms to take every day.
- Low magnesium may also affect how well vitamin D works: see magnesium and vitamin D.
- Our chart of the 12 types of magnesium if you’re choosing a supplement.
- If you start a supplement, see the best time to take magnesium, including how far apart to keep it from iron, zinc and common medicines.
- If a supplement is right for you, see magnesium powder vs tablets to choose a format you’ll take every day.
- If you think you might be running low, check how much magnesium you need per day before choosing a supplement.
- Wondering whether you need more magnesium during the change? See magnesium for menopause.
- Older adults absorb less magnesium and many eat a little less than they need: see magnesium for older adults.
- If a blood test shows low magnesium, your GP may prescribe magnesium glycerophosphate tablets rather than a shop-bought supplement.
Sources 3
- NHS. Vitamins and minerals: magnesium.
- MHRA. Proton pump inhibitors in long-term use: reports of hypomagnesaemia.
- Gröber U et al. Magnesium in prevention and therapy. Nutrients, 2015.
