What are the causes, signs, and symptoms of magnesium deficiency?

    Written by:
    Brady Holmer, Thomas Solomon
    Fact-checked by:
    Marina Shkayeva, Louie Neri
    Last Updated: February 5, 2026

    Magnesium deficiency can arise from low dietary intake, certain medications, excessive loss, or poor absorption. Symptoms include muscle cramps, muscle weakness, and vertigo. Signs include heart arrhythmias, seizures, and osteoporosis.

    Causes

    Magnesium deficiency can occur for several reasons, including the following:[1][2]

    • Insufficient dietary intake sometimes as a result of other conditions (e.g., cancer, anorexia nervosa, alcohol use disorder)
    • Certain medications (e.g., loop diuretics (e.g., furosemide), proton pump inhibitors (e.g., omeprazole), aminoglycoside antibiotics (e.g., streptomycin))
    • Excessive magnesium loss from the kidneys due to certain conditions (e.g., after a kidney transplant)
    • Poor absorption or excessive loss from the intestines due to certain conditions (e.g., diarrhea, )

    Signs and symptoms

    Signs and symptoms of deficiency can include nausea, vomiting, loss of appetite, muscle cramps and spasms, muscle weakness, fatigue, vertigo, heart arrhythmias, seizures, insulin resistance, and osteoporosis.[2][3]

    Diagnosis

    There is no simple and quick test to determine how much total magnesium there is in the body (i.e., magnesium status). Although low serum magnesium levels and a magnesium deficiency are sometimes thought of interchangeably, it is possible to have low serum magnesium levels without a deficiency and vice versa. A magnesium deficiency is commonly estimated clinically using serum magnesium levels, sometimes in combination with urinary magnesium excretion.[3][4] Serum magnesium levels below 1.5 mg/dL (0.75 mmol/L) are considered low.[3]

    References