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Magnesium supplement Pregnancy: §4.6 verbatim: 'A large amount of data on pregnant women over 16 weeks gestation (more than 1000 pregnancy outcomes) indicate no malformative nor feto/neonatal toxicity of magnesium. Magnaspartate can be used during pregnancy if clinically needed. Administration of aminoglycoside antibiotics should be avoided during this period, as there are indications of interactions.' Lactation: 'Magnaspartate can be used during breast-feeding. Magnesium aspartate/metabolites are excreted in human milk, but at therapeutic doses of Magnaspartate no effects on the breastfed newborns/infants are anticipated.' Fertility: no effects on male or female fertility are anticipated based on long-term experience.

Magnesium aspartate

Brand names: Magnaspartate

Magnesium aspartate is an oral magnesium salt used to treat or prevent magnesium deficiency and hypomagnesaemia.

Adult dose

Dose: Magnesium supplementation in adults over 18 years: 1–2 sachets daily, equal to 243–486 mg magnesium (10–20 mmol magnesium).
Route: Oral. Dissolve each sachet in 50–200 mL of water, tea or orange juice and stir until the solution in water is cloudy to transparent (inactive particles remain visible in orange juice or tea). Take immediately after reconstitution, or within 24 hours if dissolved in bottled water and stored below 25°C. If necessary, Magnaspartate in 200 mL water can be administered via a gastric, duodenal or nasal feeding tube.
Frequency: Daily. The duration of magnesium treatment required will depend on the clinical circumstances of each patient.
Max: 2 sachets daily — 486 mg magnesium (20 mmol magnesium). This is the top of the licensed adult range in §4.2; no separate ceiling is stated. Contraindicated outright in severe renal impairment (glomerular filtration rate below 30 ml/min).
VERBATIM POSOLOGY (§4.2): 'Adults (> 18 years) 1-2 sachets daily (243-486 mg magnesium or 10-20 mmol magnesium)'. The 243 mg per sachet in the product name is the magnesium content, and the SPC's own arithmetic pairs it with 10 mmol per sachet. || DOSE REDUCTION FOR DIARRHOEA (§4.4): 'If an undesirable effect occurs, such as diarrhoea, the therapy should be temporarily interrupted and can be restarted after improvement and /or elimination of the symptoms with a reduced dosage.' §4.8 repeats: 'If diarrhoea occurs, the daily dose should be reduced and gradually increased later if needed.' || CORRECT THE OTHER ELECTROLYTES TOO (§4.4): 'In the case of confirmed magnesium deficiency, concomitant hypocalcaemia and hypokalaemia should be suspected and corrected if confirmed since magnesium deficiency is frequently secondary to those conditions.' || SWITCHING BRANDS (§4.4): 'The bioavailability of magnesium preparations can vary; therefore, caution should be exercised when switching between magnesium preparations to ensure tolerability and equivalent therapeutic effect.' || EXCIPIENTS (§4.4): contains 2.706 g of sucrose per sachet — take this into account in patients with diabetes mellitus, and it may be harmful to the teeth. Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this product. Contains less than 1 mmol sodium (23 mg) per sachet, i.e. essentially sodium-free. || ELDERLY (§4.2): no dose adjustment is necessary. || SCOPE NOTE: §4.1 was not fetched, so the exact licensed indication wording is not quoted here; §4.2 and §4.4 refer throughout to magnesium treatment and to confirmed magnesium deficiency.

Paediatric dose

Route: Oral — dissolved in 50–200 mL of water, tea or orange juice
Frequency: Once daily
Max: One sachet daily (243 mg magnesium) for children aged 4 years and over; half the volume of one sachet (121.5 mg magnesium) for children aged 2 to 4 years. Not established below 2 years.
⚠️ NOT A PER-KG DOSE — dosePerKg is deliberately null. Magnaspartate is dosed in fixed sachets by AGE band, so there is no mg/kg figure to multiply by weight. §4.2 verbatim bands: 'Children and adolescents: 10 to 18 years One sachet daily (equal to 243 mg magnesium) dissolved in 50-200ml of water, tea, or orange juice.' 'Children: 4-10 years One sachet daily (equal to 243 mg magnesium) dissolved in 50-200ml of water, tea, or orange juice. Alternatively, for a half dosage, use half the volume of 1 sachet dissolved in 50-200ml of water (equal to 121.5 mg magnesium).' 'Children: 2 to 4 years Half the volume of 1 sachet dissolved in 50-200ml water (equal to 121.5 mg magnesium).' 'The safety and efficacy of Magnaspartate in children below 2 years has not been established.' Serum magnesium should be monitored at regular intervals, e.g. every 3–6 months, particularly in children (§4.2). Verify all under-18 dosing against a children's formulary.

Dose adjustments

Renal

§4.2 verbatim: 'Renal patients: Magnaspartate 243 mg is contraindicated in patients with severe renal impairment (see section 4.3). There is no dose adjustment necessary in patients with mild to moderate renal impairment.' §4.3 defines severe renal impairment as a glomerular filtration rate below 30 ml/min. Serum magnesium should be monitored at regular intervals (e.g. every 3–6 months) in patients with renal impairment, and hypermagnesaemia after oral magnesium is essentially confined to renal dysfunction (§4.2, §4.8).

Hepatic

Not stated — no hepatic-impairment dosing statement appears in any fetched section. Absence here is not a statement that no adjustment is needed.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1
  • Severe renal impairment (glomerular filtration rate below 30 ml/min)
  • Disorders of cardiac conduction (bradycardia)
  • Not a §4.3 contraindication but an excipient restriction (§4.4): patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicinal product

Side effects

  • Uncommon — soft stools or diarrhoea following high dosage
  • Very rare — fatigue if used long-term; this may indicate that an elevated magnesium level has been achieved
  • At high dosage, diarrhoea or gastrointestinal irritation may occur; if diarrhoea occurs the daily dose should be reduced and gradually increased later if needed
  • Hypermagnesaemia is rare after oral administration of magnesium salts unless there is renal dysfunction

Interactions

  • General rule (§4.5): magnesium and other medicinal products may mutually influence each other's absorption, so a time interval of 2 to 3 hours should generally be respected where possible
  • Cellulose sodium phosphate and edetate disodium — concurrent use may bind magnesium; patients should not take magnesium supplements within 1 hour of these
  • Fluorides and tetracyclines — separate doses by 2 to 3 hours or more to prevent admixture in the gut
  • Aminoquinolines, quinidine and quinidine derivatives, nitrofurantoin, penicillamine, iron, bisphosphonates, eltrombopag, nitroxoline — take magnesium 3 to 4 hours before or after these to avoid impairment of absorption
  • Increased magnesium losses, so a magnesium dose adjustment may be needed with: aminoglycoside antibiotics, cisplatin and ciclosporin A; diuretics (such as thiazides and furosemide); EGF-receptor antagonists (such as cetuximab and erlotinib); proton pump inhibitors (such as omeprazole and pantoprazole); and the viral DNA polymerase inhibitors foscarnet, pentamidine, rapamycin and amphotericin B
  • Aminoglycoside antibiotics should be avoided during pregnancy while on magnesium, as there are indications of interactions (§4.6)

Monitoring

  • Monitor serum magnesium at regular intervals, e.g. every 3–6 months, particularly in children and in patients with renal impairment (§4.2)
  • In confirmed magnesium deficiency, suspect and correct concomitant hypocalcaemia and hypokalaemia — magnesium deficiency is frequently secondary to those conditions (§4.4)
  • Watch for diarrhoea or GI irritation as a dose-limiting effect, and for long-term fatigue as a possible sign of an elevated magnesium level (§4.4, §4.8)
  • Take the sucrose content (2.706 g per sachet) into account in patients with diabetes mellitus (§4.4)

Clinical monograph

How it works

It supplies elemental magnesium, an essential cofactor for numerous enzymatic reactions and for neuromuscular and cardiac function, correcting a deficiency state.

Prescribing in practice

  • Use with caution and reduced exposure in significant renal impairment, where magnesium can accumulate and cause hypermagnesaemia.
  • Diarrhoea is the most common dose-limiting side effect of oral magnesium salts.
  • Oral magnesium may reduce absorption of some drugs, such as certain antibiotics, so separate the timing of administration.

Monitoring

Monitor serum magnesium, and renal function where relevant, to confirm replacement and avoid accumulation.

Counselling the patient

  • Take with food to reduce stomach upset.
  • Loose stools may occur; report persistent diarrhoea.
  • Separate from certain other medicines by an interval as advised.

Evidence & guidelines

Oral magnesium salts are standard, well-established therapy for correcting and preventing magnesium deficiency.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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