Reflux suppressant (low-sodium) Pregnancy: §4.6: clinical studies in more than 500 pregnant women plus a large amount of post-marketing data indicate no malformative or foeto/neonatal toxicity of the active substances; Gaviscon can be used during pregnancy if clinically needed. Breast-feeding: no known effect on breast-fed infants — can be used during breast-feeding. Fertility: no known effect on human fertility.

Sodium alginate with potassium bicarbonate

Brand names: Acidex

This is an alginate reflux suppressant combining sodium alginate with potassium bicarbonate, used for symptomatic relief of gastro-oesophageal reflux and heartburn, including in pregnancy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 5-10 ml

Route: Oral

Frequency: After meals and at bedtime

UK SPC (Gaviscon Advance Aniseed Oral Suspension) §4.2: adults and children 12 years and over — 5-10 ml after meals and at bedtime. Children under 12 years: should be given only on medical advice (no paediatric dose is stated). Elderly: no dose modification required. Hepatic impairment: no dose modification necessary. No explicit maximum number of doses per day is stated in §4.2. If symptoms do not improve after 7 days the clinical situation should be reviewed (§4.4). Excipient/content warnings from §4.4: 57.85 mg sodium per 5 ml, equivalent to 2.9% of the WHO recommended maximum daily intake for sodium (maximum daily dose equivalent to 23.14%) — considered high in sodium, relevant to patients on a low salt diet (e.g. some cases of congestive heart failure and renal impairment); 1 mmol (39.06 mg) potassium per 5 ml — to be taken into consideration by patients with reduced kidney function or on a controlled potassium diet; §4.4 also states each 10 ml contains 200 mg (2 mmol) calcium carbonate, with care needed in hypercalcaemia, nephrocalcinosis and recurrent calcium-containing renal calculi; contains 0.525 mg benzyl alcohol per 5 ml and methyl (E218) / propyl (E216) parahydroxybenzoate, which may cause allergic reactions.

Dose adjustments

Renal

§4.2 renal insufficiency: caution if a highly restricted salt diet is necessary. §4.4: the potassium content (1 mmol per 5 ml) is to be taken into consideration in patients with reduced kidney function. No numeric dose adjustment is stated.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known or suspected hypersensitivity to any of the ingredients or to any of the excipients, including methyl parahydroxybenzoate (E218) and propyl parahydroxybenzoate (E216)

Side effects

Diarrhoea (uncommon)
Nausea (uncommon)
Vomiting (uncommon)
Anaphylactic and anaphylactoid reactions, and hypersensitivity reactions such as urticaria (very rare)
Respiratory effects such as bronchospasm (very rare)

Interactions

Allow a 2-hour interval between Gaviscon and the administration of other medicinal products, especially tetracyclines, fluoroquinolones, iron salts, thyroid hormones, chloroquine, bisphosphonates and estramustine (§4.5)

Clinical monograph

How it works

On contact with gastric acid the alginate forms a viscous gel raft that floats on the stomach contents, while bicarbonate reacts with acid to generate carbon dioxide that buoys the raft, physically reducing reflux of acid into the oesophagus.

Prescribing in practice

The potassium content means caution is needed in renal impairment and with other sources of potassium or potassium-sparing drugs; the sodium content is relevant where salt intake must be restricted.
It should be separated in time from other medicines, as the raft can impair absorption of co-administered drugs.
It is intended for short-term symptomatic relief and is taken after meals and at bedtime; persistent symptoms warrant review.

Monitoring

No routine monitoring is needed for short-term use, but consider potassium and sodium load in renal impairment or where electrolyte intake is restricted.

Counselling the patient

Take after meals and at bedtime for best effect.
Leave a gap before or after other medicines.
Seek review if heartburn persists, worsens or is accompanied by difficulty swallowing or weight loss.

Evidence & guidelines

Alginate raft-forming preparations provide established symptomatic relief of reflux and are recommended within NICE dyspepsia and GORD guidance.

Reference: NICE CG184; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. 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).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways