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ingestible · for respiratory health & asthma

Oral Magnesium Supplementation

Reviewed by the Nimbera editorial team · Last updated May 2026

Kazaks et al. (2010), Journal of Asthma, n=55 adults with mild-to-moderate asthma: a 6.5-month placebo-controlled RCT found oral magnesium supplementation improved peak expiratory flow rate by 5.8% predicted, reduced bronchial reactivity to methacholine challenge, and significantly improved asthma quality of life scores compared with placebo. PMID: 20100026.$10-20/month

How to use

Take 300-400 mg of elemental magnesium daily, preferably as magnesium glycinate or magnesium citrate (better absorbed than magnesium oxide). Split into two doses with meals to reduce gastrointestinal effects. Allow 6-8 weeks to assess benefit. Eating magnesium-rich foods (dark leafy greens, pumpkin seeds, almonds) alongside supplementation supports overall status.

How it works

Magnesium acts as a natural calcium channel antagonist in airway smooth muscle cells, reducing intracellular calcium-driven bronchoconstriction. It also suppresses mast cell degranulation and histamine release, dampening the early allergic response in airways.

Where to buy

Pharmacies (CVS, Walgreens, Rite Aid), health food stores, and online. Magnesium glycinate and citrate forms are widely available. Avoid cheap magnesium oxide formulations due to poor bioavailability.

Typical cost: $10-20/month

Safety notes

Magnesium can reduce absorption of tetracycline and fluoroquinolone antibiotics by 50-90% - separate doses by at least 2-4 hours. May slightly reduce warfarin efficacy - inform your anticoagulant clinic if you start supplementing. High doses (above 500 mg/day elemental magnesium) commonly cause loose stools or diarrhea; reduce dose if this occurs. Magnesium supplements are contraindicated in kidney disease (impaired clearance can cause dangerous hypermagnesemia). Always check with your doctor before supplementing if you have heart disease or take diuretics.

Drug & supplement interactions

  • Always tell your doctor or pharmacist about any supplements you take.
  • Interactions can occur with prescription medications, blood thinners, and immunosuppressants.
  • Herbal remedies can affect how the body absorbs or metabolises drugs.
  • Check drugs.com interactions checker before starting.

Clinical source

Kazaks et al., J Asthma 2010

This information is compiled from primary clinical literature and is for informational purposes only. It is not a substitute for professional medical advice. Read our full disclaimer.