ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Antacid Pregnancy: Compatible in short-term use — magnesium and aluminium poorly absorbed. Avoid prolonged high-dose use (aluminium exposure). Gaviscon preferred for GORD in pregnancy.

Co-magaldrox (Aluminium and Magnesium Hydroxide)

Brand names: Mucogel

Adult dose

Dose: 10–20mL 20–60 minutes after meals and at bedtime (as required for symptomatic relief of dyspepsia, heartburn, or acid regurgitation).
Route: Oral (suspension)
Frequency: After meals and at bedtime (as required — up to 4 times daily)
Max: 80mL/day
Contains aluminium hydroxide (200mg/5mL) + magnesium hydroxide (195mg/5mL) per Mucogel suspension. Aluminium tends to cause constipation; magnesium tends to cause diarrhoea — combination balances GI effects. Shake well before use. Short-term symptomatic relief only — investigate underlying cause if symptoms persist >2 weeks.

Paediatric dose

Route: Oral
Frequency: After meals
Max: 10mL per dose
Children ≥12 years: adult dose. Children <12 years: seek specialist advice. Aluminium hydroxide not recommended in young children (neurotoxicity risk with accumulation). Source: BNF for Children 2024.

Dose adjustments

Renal

Avoid in severe renal impairment (eGFR <30) — aluminium accumulates causing encephalopathy and osteomalacia; magnesium causes hypermagnesaemia.

Hepatic

No dose adjustment required.

Clinical pearls

  • Antacids provide rapid but short-lived (20–60 minute) symptom relief. Take 1–2 hours after food for maximum benefit (food-delayed gastric emptying allows antacid to remain in stomach longer).
  • Aluminium in renal failure: even short-term use of aluminium-containing antacids causes aluminium accumulation in dialysis patients — use calcium carbonate or magnesium-only antacids instead.
  • Drug interaction window: most oral drugs should be separated by at least 2 hours from antacid administration — aluminium and magnesium ions chelate many drugs.
  • OTC availability: widely available — ask about OTC antacid use when prescribing interacting drugs.

Contraindications

  • Severe renal impairment (aluminium and magnesium toxicity)
  • Hypophosphataemia (aluminium binds dietary phosphate)

Side effects

  • Constipation (aluminium component — dose-dependent)
  • Diarrhoea (magnesium component)
  • Aluminium accumulation in renal failure (encephalopathy, osteomalacia)
  • Hypermagnesaemia (in renal impairment — drowsiness, cardiac arrest at high levels)
  • Hypophosphataemia (aluminium binds phosphate — with prolonged use)

Interactions

  • Multiple drugs — antacids reduce absorption of tetracyclines, fluoroquinolones, iron, ketoconazole, itraconazole, digoxin, bisphosphonates, thyroid hormones. Separate by at least 2 hours.
  • Enteric-coated tablets: antacids destroy enteric coating if taken simultaneously — separate by 1–2 hours

Monitoring

  • Symptom response
  • Renal function (if regular use)
  • Aluminium level (if renal impairment)
  • Serum phosphate (prolonged use)

Reference: BNFc; BNF 90; SPC Mucogel; NICE CG17 Dyspepsia. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Drugs
Pathways