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SYMPTOMS

Muscle cramps or twitches

Everyday reasons for muscle cramps, what to ask your doctor to check, and which nutrients have been studied.

Also described as: cramp, cramps, charley horse, twitch, eyelid twitch, spasm

Common everyday causes

Low magnesium

Magnesium relaxes muscles and nerves and is used in hundreds of energy reactions. Diet, stress, alcohol, acid reducers and water pills all lower it. Ask for a red-blood-cell (RBC) magnesium test; serum magnesium misses most low levels.

Fluids and electrolytes (sweat losses)

Heavy sweating and too little fluid or salt bring on exercise cramps. No test needed at first.

Low vitamin D

Vitamin D supports muscles, bones, mood and immune defenses. Low levels are very common, especially in winter, with darker skin or little sun. Ask for a 25-hydroxy vitamin D test.

Low vitamin B12

B12 keeps nerves and red blood cells healthy; low levels cause tiredness, brain fog and tingling. Common with metformin, acid reducers, a plant-based diet and after weight-loss surgery. Ask for a vitamin B12 test (and methylmalonic acid if it’s borderline).

Low iron stores

Iron carries oxygen and powers energy production; stores (ferritin) run low well before anemia shows, especially with heavy periods or a plant-based diet. Ask for a ferritin test (with a complete blood count).

An underactive thyroid

The thyroid sets your metabolic pace; when it slows, energy, mood, hair, skin and bowels slow too. It is common in women and after pregnancy, and it needs a doctor, not a supplement. Ask for TSH and free T4 (plus TPO antibodies).

If you take certain medicines

Acid reducer lowering magnesium and B12

Long-term acid reducers (especially PPIs) lower magnesium and B12 absorption. Ask for magnesium and B12 tests, and whether you still need the acid reducer.

Statin lowering CoQ10

Statins block the same pathway the body uses to make CoQ10, an energy molecule in muscle cells. Muscle aches and tiredness are the most common statin complaints. Tell your prescriber about muscle symptoms; they may check CK. There’s no routine CoQ10 test.

Metformin lowering B12

Metformin reduces B12 absorption; about 1 in 10 long-term users become deficient. Ask for a B12 test — the ADA advises checking it regularly on metformin.

GLP-1 medicine: eating less protein and nutrients

GLP-1 medicines cut appetite so much that protein and micronutrients often fall short; fast weight loss also triggers hair shedding. Ask for B12, ferritin and vitamin D tests; aim for 25–30 g of protein per meal.

What’s been studied

• Vitamin D3

  For low vitamin D.

• Vitamin K2

  For low vitamin D.

• Iron

  For low iron. Only with a lab result that shows it’s needed.

• Vitamin C

  For low iron. Only with a lab result that shows it’s needed.

• Selenium

  For thyroid. Only with a lab result that shows it’s needed.

• Magnesium

  For low magnesium.

• CoQ10

  For statin & CoQ10.

• Vitamin B12

  For low B12.

• Magnesium

  For GLP-1 medicine.

From the Journal

• Magnesium glycinate vs citrate vs oxide: which form should you take?

  Glycinate, citrate, oxide, malate, threonate and taurate compared on magnesium content, absorption, gut comfort and capsule space, plus the 350 mg supplement limit and medicine timing.

• How much creatine should you take a day, and is it safe?

  Creatine dosing made simple: 3 g vs 5 g a day, why loading is optional, what the brain research does and doesn't show, the creatinine lab quirk, and who should check first.

apiece asks a few quick questions about muscle cramps in its quiz to tell these causes apart, and suggests only ingredients studied for the likely ones.

Questions

What can cause muscle cramps?

Common everyday reasons include low magnesium, fluids & electrolytes, low vitamin D, low B12, low iron. A doctor can help find which applies to you.

What tests can help explain muscle cramps?

Ask your doctor about: a red-blood-cell (RBC) magnesium test; serum magnesium misses most low levels; No test needed at first; a 25-hydroxy vitamin D test; a vitamin B12 test (and methylmalonic acid if it’s borderline); a ferritin test (with a complete blood count); TSH and free T4 (plus TPO antibodies).

Which supplements are studied for muscle cramps?

Depending on the cause: Vitamin D3, Vitamin K2, Iron, Vitamin C, Selenium, Magnesium, CoQ10, Vitamin B12, Magnesium. Some only make sense with a lab result (for example iron only when ferritin is low).*

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This page is general information, not medical advice. Check with your doctor or pharmacist before starting a supplement, especially if you take medication, are pregnant or nursing, or have a health condition. Updated 2026-10-21.