Magnesium

What is Magnesium?

Magnesium is a mineral found in many foods and also in some medicines, such as antacids and laxatives. An adult body contains about 25 g, mostly in bones and soft tissues.^[1]

Its role in the body

• Helps more than 300 enzyme systems, including those that make energy, protein, DNA and bone.^[1]
• Needed for muscle and nerve function, blood sugar control and blood pressure regulation.^[1]

Important food sources

• Whole grains such as whole-wheat atta, millets, brown rice and oats
• Dals, rajma, chana and other legumes
• Nuts and seeds such as almonds, cashews, peanuts and pumpkin seeds
• Green leafy vegetables such as spinach
• TipFoods that contain dietary fibre usually also provide magnesium.

Recommended dietary intake

Signs sometimes associated with low levels

• Early signs can include loss of appetite, nausea, vomiting, tiredness and weakness.^[1]
• More severe deficiency can cause numbness, muscle cramps, seizures and abnormal heart rhythms.^[1]
• Deficiency with symptoms is uncommon in healthy people because the kidneys hold on to magnesium when intake is low.^[1]

Why symptoms alone cannot confirm a deficiency

Signs like tiredness, weakness, hair fall or low mood are very common and have many possible causes, such as poor sleep, stress, infections, thyroid problems or other illnesses.

The same sign can come from several different nutrients, or from no nutrient problem at all.

Only a qualified clinician, using your history, an examination and, when needed, lab tests, can say whether a deficiency is present. This app cannot diagnose a deficiency from symptoms or from BMI.

Muscle cramps, tiredness and poor sleep are very common and usually have other causes.

Tests a clinician might consider

• Blood (serum) magnesium is the most common test, but less than 1% of the body’s magnesium is in the blood, so a normal result does not always reflect body stores. Clinicians may combine it with other assessments.^[1]

Who is more likely to have low intake

• People with digestive diseases such as Crohn’s disease or celiac disease.^[1]
• People with type 2 diabetes, who may lose more magnesium in urine.^[1]
• People with alcohol dependence.^[1]
• Older adults, who tend to eat less magnesium, absorb less and lose more through the kidneys.^[1]

Potential benefits and quality of evidence

• Magnesium is essential for muscles, nerves, bones and energy production.^[1] Established
• Supplements lower blood pressure only slightly in clinical trials.^[1] Limited evidence
• People who eat more magnesium tend to have lower risk of type 2 diabetes, but trials of supplements to manage diabetes give mixed results.^[1] Limited evidence
• Neurology groups consider magnesium probably effective for preventing migraine, although the data are limited; this is a decision for a doctor.^[1] Moderate evidence
• It is not known whether magnesium supplements help prevent or manage osteoporosis.^[1] Not enough evidence

Side effects

• High doses from supplements or medicines often cause diarrhoea, sometimes with nausea and stomach cramps.^[1]

Risks of too much

• Magnesium from food is not a risk for healthy people because the kidneys remove the excess.^[1]
• Very large doses, usually from laxatives or antacids, can cause magnesium toxicity: low blood pressure, vomiting, muscle weakness, breathing difficulty, irregular heartbeat and, rarely, death. The risk is higher when the kidneys do not work well.^[1]

Medicine and supplement interactions

• Oral bisphosphonates (osteoporosis medicines, e.g., alendronate): Magnesium-rich supplements or medicines can reduce their absorption; doses are usually separated.^[1]
• Tetracycline and quinolone antibiotics: Magnesium can bind to these antibiotics and reduce absorption; timing should follow the doctor’s or pharmacist’s advice.^[1]
• Loop and thiazide diuretics: Long-term use can increase magnesium loss in urine. Potassium-sparing diuretics reduce magnesium loss.^[1]
• Proton pump inhibitors (e.g., omeprazole, esomeprazole) used long-term: Can cause low blood magnesium, usually after more than a year of use.^[1]

Never start, stop or change a prescribed medicine because of this list — talk to your doctor or pharmacist.

Pregnancy and breastfeeding

• Needs rise slightly in pregnancy. The upper limit for supplemental magnesium still applies. Use supplements in pregnancy only as advised by your doctor.^[1]

Kidney and liver cautions

• People with reduced kidney function or kidney failure are at higher risk of magnesium toxicity and should not take magnesium supplements, antacids or laxatives containing magnesium without medical advice.^[1]

Upper intake limits

When to talk to a professional

Talk to a doctor or registered dietitian before starting a supplement, especially if you are pregnant or breastfeeding, have a long-term illness, or take any regular medicines.

Do not start, stop or change a prescribed medicine because of anything you read here.

Supplements sold without a prescription are not automatically safe. Doses, quality and interactions still matter.

Seek medical care promptly if you have severe, sudden or worsening symptoms.

Check with a pharmacist before combining magnesium supplements with antacids, laxatives or antibiotics.

Still being verified

• ICMR-NIN 2020 values for pregnancy/lactation and Tolerable Upper Limit not verified; not stated.

References

1. NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Health Professionals (opens in a new tab) (2026-01-06). Accessed 9 Oct 2026.
2. ICMR-National Institute of Nutrition (India). A Brief Note on Nutrient Requirements for Indians, the Recommended Dietary Allowances (RDA) and the Estimated Average Requirements (EAR), ICMR-NIN, 2020 (opens in a new tab). Accessed 9 Oct 2026.

Sources checked: 9 Oct 2026