Magnesium Supplement

Reviewed on 9/21/2021

What Is Magnesium Supplement Used For and How Does it Work?

Magnesium supplement is an over-the-counter (OTC) supplement used to treat magnesium deficiency and renal insufficiency.

Magnesium supplement is available under the following different brand names: Mag-Tab SR.

Dosages of Magnesium Supplement


  • 84 mg

Dosage Considerations – Should be Given as Follows:

Magnesium Deficiency

  • 168-336 mg orally divided twice daily
  • CrCl less than 30 mL/minute: Use caution; monitor for hypermagnesemia
  • CrCl 30 mL/minute or greater: Dose adjustment not necessary


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What Are Side Effects Associated with Using Magnesium Supplement?

Side effects of Magnesium Supplement include:

  • Diarrhea

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Magnesium Supplement?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

  • Drug interactions of magnesium supplement include:
    • baloxavir marboxil
    • raltegravir
  • Magnesium supplement has moderate interactions with at least 51 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Magnesium Supplement?


This medication contains magnesium supplement. Do not take Mag-Tab SR if you are allergic to magnesium supplement or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


  • Hypersensitivity

Effects of Drug Abuse

  • No information available.

Short-Term Effects

  • See "What Are Side Effects Associated with Using Magnesium Supplement?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Magnesium Supplement?"


  • Use with caution in patients with neuromuscular disease, including myasthenia gravis
  • Diets high in fat may cause decreased magnesium absorption
  • Monitor patients with severe renal impairment for magnesium toxicity; use caution
  • When used for self-medication, not for long term use; not for use if nausea, vomiting, or abdominal pain present; patients with impaired kidney function should use under the supervision of healthcare provider

Pregnancy and Lactation

Use of magnesium supplement has not been studied during pregnancy. Magnesium crosses the placenta; the effects of supplementation on neonates are unknown. Magnesium is present in breast milk; supplementation is generally considered compatible with breastfeeding.


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