Symptoms of Magnesium Deficiency

Mild magnesium deficiency often causes no symptoms. Symptoms usually appear when levels are quite low, and they overlap with low calcium and potassium.

Early or mild symptoms

• Tiredness and weakness
• Loss of appetite, nausea and vomiting
• Muscle twitching or cramps

Moderate symptoms

• Muscle spasms, tremor and stiffness
• Numbness and tingling in the hands, feet or around the mouth
• Poor concentration, irritability and low mood
• Palpitations or a feeling that the heart skips beats

Severe symptoms

• Abnormal heart rhythms, which can be life-threatening
• Seizures
• Severe muscle weakness
• Confusion or personality changes
• Unsteady walking or abnormal eye movements

Related findings

• Low calcium: tingling and cramps, and in severe cases spasms of the hands (tetany)
• Low potassium: weakness and palpitations, and cramps

Symptoms that are not from magnesium alone

Fatigue, cramps and palpitations have many other causes, such as anaemia, thyroid disease, dehydration, low sodium and heart disease. A test is needed before blaming magnesium.

See a doctor soon if

You have repeated muscle cramps, tremors, tingling or palpitations, especially with alcohol use, long-term diarrhoea, diabetes or use of diuretics or acid-reducing medicines.

Emergency signs: call 112

Seizures, fainting, severe weakness, chest pain, or a very fast, slow or irregular heartbeat.

Key point

Symptoms are vague, so a blood test is needed to confirm low magnesium.

Before your appointment

Note your symptoms, when they began, and what makes them better or worse. Mention alcohol use, diarrhoea, vomiting, diabetes, kidney disease, bowel conditions and any recent illness. List all medicines, especially diuretics, acid-reducing medicines, antibiotics, supplements and herbal products. Write down your usual diet and any antacids or laxatives you take. Ask about blood tests for magnesium, potassium and calcium, and whether an ECG is needed. Call 112 for seizures, fainting, severe weakness or a very irregular heartbeat.