What Is Magnesium Citrate? Uses, Dosage, and What You Need to Know in 2026

Magnesium citrate is both a laxative and a mineral supplement — two different uses for the same compound. Understanding which use applies to you determines which form you need, how much to take, and what to expect.

What Is Magnesium Citrate?

Magnesium citrate (chemical name: trimagnesium dicitrate, formula C₁₂H₁₀Mg₃O₁₄) is a compound formed by combining magnesium — an essential mineral — with citric acid. It belongs to the drug class of saline laxatives and is also classified as a dietary supplement.

In the United States, it is available entirely over the counter — no prescription required. It is sold under multiple brand names including Citroma, Citrate of Magnesia, and ColonX, as well as generic store brands from Walmart (Equate), CVS, Walgreens, and Target (Up & Up).

What Is Magnesium Citrate Used For?

Magnesium citrate has two primary uses:

1. As a Laxative (Constipation and Colonoscopy Prep)

The 10 fl oz liquid bottle is the standard laxative form. It is used for:

• Occasional constipation: Provides relief in 30 minutes to 6 hours. Not for long-term regular use.
• Colonoscopy bowel preparation: Prescribed by gastroenterologists as part of a prep protocol to clear the colon before a colonoscopy procedure.
• Pre-surgery bowel prep: Used by surgeons to clear the bowel before certain GI surgeries.

2. As a Magnesium Supplement

Magnesium citrate capsules and tablets are used to replenish magnesium levels. Magnesium is an essential mineral needed for over 300 enzymatic processes. Deficiency is common — surveys suggest up to 50% of Americans don't meet their daily magnesium RDA (310–420 mg/day for adults).

Evidence-supported uses for magnesium supplementation include: migraine prevention, blood pressure support, sleep quality improvement, muscle cramp reduction, and glycemic control in people with diabetes. These are supplement claims, not FDA-approved drug indications — but the scientific evidence for several of these is substantial.

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What Forms Does Magnesium Citrate Come In?

• Oral liquid (1.745 g/30 mL): 10 fl oz bottle. Cherry, lemon, or unflavored. Used for laxative/prep purpose.
• Capsules (100 mg, 125 mg, 133 mg): Used as daily magnesium supplement.
• Tablets (100 mg): Supplement form.
• Chewable tablets (34–85 mg): Lower dose, easier to take for children or those with swallowing difficulties.

What Is the Correct Dosage?

Dosage depends entirely on the purpose:

• Laxative (adults and children 12+): ½ to 1 bottle (5–10 fl oz) in a 24-hour period, taken as a single dose or divided throughout the day. Always take with a full 8 oz glass of water.
• Supplement (adults): 100–400 mg elemental magnesium per day. Start at the lower end (100–200 mg) and increase gradually if tolerated. The RDA for adults is 310–420 mg/day from all dietary sources combined.
• Children (6–11 years, laxative): As directed by a healthcare provider. Do not administer to children under 6 without medical guidance.

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Important Safety Considerations

• Kidney disease: Avoid in CKD Stages 3–5 — risk of hypermagnesemia.
• Drug interactions: Take other oral medications at least 2 hours before or after magnesium citrate. Key interactions include antibiotics (tetracyclines, fluoroquinolones) and HIV integrase inhibitors.
• Not for long-term laxative use: Laxative doses are for occasional use only (less than 1 week at a time). Chronic use can cause electrolyte imbalances.
• Not a controlled substance: Magnesium citrate has no DEA scheduling; no special prescription requirements apply.

The Bottom Line

Magnesium citrate is safe, effective, and affordable for most people when used correctly. Know your purpose (laxative vs. supplement), use the right form and dose, and avoid it if you have kidney disease. For a full review of what to watch for, read our side effects guide.