Magnesium deficiency: 11 symptoms you shouldn't ignore
What is magnesium deficiency?
Magnesium deficiency means the body has too little magnesium to function optimally. The mineral is involved in hundreds of enzyme processes and contributes, among other things, to normal muscle and nerve function and to a reduction of tiredness. True deficiency is rare in healthy people, but low levels are more common than many think.
11 symptoms of magnesium deficiency
The symptoms are non-specific and can have many other causes. But several at the same time, especially if your diet is one-sided or you drink a lot of alcohol, can be a sign.
- Muscle cramps and twitches
- Tiredness and lack of energy
- Muscle weakness
- Trembling or tingling
- Irritability and restlessness
- Poor sleep
- Headaches
- Heart palpitations
- Poor appetite and nausea
- Constipation
- Low mood
Magnesium contributes to normal psychological function and to normal functioning of the nervous system, which explains why both mood and muscles are affected when levels are low.
Why does magnesium deficiency occur?
Common causes are a one-sided diet, high alcohol intake, chronic gastrointestinal conditions that impair absorption, and certain medicines – particularly diuretics and acid-reducing drugs. Heavy sweating and prolonged stress can also drain the body's stores.
| Risk group | Why |
|---|---|
| High alcohol intake | Increased excretion via the urine |
| Type 2 diabetes | Greater losses via the kidneys |
| Gastrointestinal disease | Poorer absorption in the gut |
| Older adults | Lower intake and absorption |
Magnesium contributes to a reduction of tiredness and fatigue and to normal muscle function.
See current price »How do you know if you're deficient?
A standard blood test measures magnesium in serum, but only around 1 per cent of the body's magnesium is found in the blood – the rest sits in bone and cells. The test can therefore look normal even when stores are low. Doctors therefore weigh up test results, symptoms and diet together. If you suspect a deficiency, raise it with your doctor.
How do you correct low levels?
Start with food. Nuts, seeds, legumes, whole grains and dark chocolate are rich sources – see the full list of magnesium-rich foods. If that isn't enough, a supplement around the reference intake of 375 mg can help. How to get the dose right is covered in our guide to how much magnesium per day you need.
If you want to dig deeper into what the mineral does, see our overview of what magnesium is good for. You'll find products in the daily support collection and a comparison at best magnesium.
When should you seek medical advice?
Contact a doctor if you have severe muscle weakness, an irregular heartbeat, recurring cramps, or if you take medicines that can lower magnesium. Never stop prescribed medication on your own, and check supplements with a pharmacist if you take several medicines.
How does magnesium deficiency affect sleep?
Magnesium contributes to normal functioning of the nervous system, and low levels can make it harder to wind down. Many people with a low intake describe lighter sleep, more awakenings and a feeling of restlessness in the evening. The relationship runs both ways: poor sleep raises stress levels, and stress in turn drains magnesium stores. Topping up magnesium through food and possibly a supplement is therefore a sensible first step. Read more about the connection in our overview of magnesium and sleep.
Can stress cause magnesium deficiency?
Yes, prolonged stress can increase the excretion of magnesium via the urine. At the same time, the body needs magnesium to cope with stress, since the mineral contributes to normal psychological function. That creates a vicious circle where stress lowers your levels, and low levels make stress harder to handle. People going through periods of high pressure, poor sleep and irregular meals therefore often run low, even if their diet is otherwise reasonable.
Magnesium deficiency and the heart
Magnesium is important for the heart's normal function and for allowing muscles to relax. With pronounced deficiency, palpitations and an irregular heartbeat can occur. This is one of the symptoms you should not ignore – if you experience recurring palpitations, dizziness or breathlessness, contact a doctor for an assessment, whatever you think is behind it. Heart rhythm disturbances have many possible causes and should always be investigated.
Do symptoms differ between mild and pronounced deficiency?
Yes. Slightly low levels often cause diffuse complaints such as tiredness, irritability and minor muscle twitches, which are easy to blame on something else. With more pronounced deficiency, the symptoms become clearer: severe cramps, muscle weakness, nausea and, in rare cases, effects on heart rhythm. Because the transition is gradual and the tests are blunt instruments, it's the pattern of symptoms over time that tells you most. Several signs at once, especially in a risk group, are a signal to review both your diet and any supplements.
How to rebuild your magnesium stores
Replenishing low magnesium stores is rarely complicated, but it takes time. Start with your diet, since food delivers magnesium alongside other nutrients and is easy for the body to handle. Add a handful of nuts or seeds a day, switch to whole grains and eat legumes and green leafy vegetables regularly. If diet isn't enough – for example if you eat a one-sided diet or have an increased need – a supplement around the reference intake of 375 mg can help. Choose a form you tolerate well; citrate and glycinate are absorbed well, while oxide more often causes loose stools. Take the dose with a meal to reduce the risk of stomach upset, and split it up if your stomach is sensitive. Magnesium contributes to a reduction of tiredness and fatigue and to normal muscle function, and many people notice a gradual difference over a few weeks. Give it at least a month before you evaluate. If your symptoms persist despite a reasonable intake, the cause should be investigated further, since the symptoms may be down to something other than magnesium. How to get the dose right is covered in our guide to how much magnesium per day you need.
How do you tell deficiency from plain tiredness?
Tiredness is one of the most non-specific symptoms there is and is usually caused by something other than magnesium – too little sleep, stress, iron deficiency or a cold coming on. So don't let tiredness alone convince you that you have magnesium deficiency. What makes the picture more suspicious is when several signs cluster together: tiredness combined with muscle twitches, cramps, irritability and poor sleep, especially if you also eat a one-sided diet, drink a lot of alcohol or take medicines that lower magnesium. Then it makes sense both to review your diet and to raise it with a doctor. A doctor can weigh up your symptoms, your habits and any test results, and rule out other causes before you settle on magnesium as the explanation. That way you avoid both missing another explanation and spending money on supplements you may not need.
Frequently asked questions
What are the most common symptoms of magnesium deficiency?
The most common are muscle cramps, twitches, tiredness, irritability, headaches and poor sleep. The symptoms are non-specific and can have other causes, but several at once – especially with a one-sided diet or high alcohol intake – can point to low levels. Raise recurring complaints with a doctor for a proper assessment.
Can magnesium deficiency be seen on a blood test?
Only partly. A standard test measures magnesium in the blood, but only around one per cent of the body's magnesium is found there – the rest sits in bone and cells. The test can therefore look normal even when stores are low. That's why doctors weigh up test results, symptoms and dietary habits in their assessment.
Who is most at risk of magnesium deficiency?
Those most at risk are people with high alcohol intake, type 2 diabetes, chronic gastrointestinal conditions and those with a very one-sided diet. Older adults and people on diuretics or acid-reducing medicines are also in the risk zone. If you belong to one of these groups, it's wise to prioritise magnesium-rich foods and check in with your doctor.
How quickly do magnesium levels recover?
With increased intake through diet and possibly a supplement, levels usually improve over a few weeks. Magnesium contributes to a reduction of tiredness and fatigue, and many people notice a gradual difference. Take a sensible dose around the reference intake and give it time – if symptoms persist, the cause should be investigated by a doctor.