Reflux suppressant (alginate raft + antacid) Pregnancy: §4.6: clinical studies in more than 500 pregnant women plus a large amount of post-marketing data indicate no malformative or feto/neonatal toxicity of the active substances; this medicine can be used during pregnancy if clinically needed. Breast-feeding: no effects shown in breastfed newborns/infants of treated mothers — can be used during breast-feeding. Fertility: no negative effect indicated.

Sodium alginate with calcium carbonate and sodium bicarbonate

Brand names: Gaviscon Advance, Peptac

A compound alginate-antacid raft-forming preparation used for the symptomatic relief of gastro-oesophageal reflux, heartburn and acid regurgitation, 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: Two to four 5 ml spoonfuls (10-20 ml)

Route: Oral

Frequency: After meals and at bedtime

UK SPC (Acidex Aniseed Flavour Oral Suspension, PL04917/0021) §4.2: adults and children over 12 years — two to four 5 ml spoonfuls; doses should be taken after meals and at bedtime. Children under 12 years: should be given only on medical advice (no paediatric dose is stated). Elderly: no dosage modification required. Hepatic impairment: no dose modification necessary. No explicit maximum number of doses per day is stated in §4.2. This medicine should not be taken within 1 to 2 hours of taking other medicines by mouth; if symptoms do not improve after seven days the clinical situation should be reviewed (§4.4). §4.4 states the product contains 286.5 mg (12.45 mmol) sodium per 20 ml dose, equivalent to 14.3% of the WHO recommended maximum daily intake for sodium, and that the maximum daily dose of the product is equivalent to 57.2% of that intake — the product is considered high in sodium, which matters particularly for patients on a low salt diet (e.g. some cases of congestive heart failure and renal impairment). Each 10 ml dose contains 160 mg (1.6 mmol) calcium carbonate — care is needed in patients with hypercalcaemia, nephrocalcinosis and recurrent calcium-containing renal calculi.

Dose adjustments

Renal

§4.2 renal insufficiency: caution if a highly restricted salt diet is necessary (see §4.4 sodium content). 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 the active substances or to any of the excipients, including ethyl parahydroxybenzoate (E214), propyl parahydroxybenzoate (E216) and butyl parahydroxybenzoate

Side effects

Anaphylactic and anaphylactoid reactions (very rare)
Hypersensitivity reactions such as urticaria (very rare)
Respiratory effects such as bronchospasm (very rare)

Interactions

Allow a 2-hour interval between this medicine and other medicinal products, especially tetracyclines, digoxin, fluoroquinolones, iron salts, ketoconazole, neuroleptics, thyroid hormones, penicillamine, beta-blockers (atenolol, metoprolol, propranolol), glucocorticoids, chloroquine, bisphosphonates and estramustine
Antacids alter gastric pH and may affect dissolution, solubility or ionisation of other drugs; absorption is reduced for ACE inhibitors, analgesics, antibacterials, antiepileptics, antifungals, antimalarials, antipsychotics, bisphosphonates, lithium and penicillamine
Antacids may increase urinary pH and affect drug elimination — excretion of basic drugs is decreased whereas acidic drugs are eliminated more rapidly
Sodium bicarbonate may reduce plasma lithium levels and increase plasma quinidine levels (renal-level effects)

Clinical monograph

How it works

On contact with gastric acid the alginate precipitates into a viscous gel raft that floats on the stomach contents and physically impedes reflux, while the carbonate components neutralise acid and generate the gas that buoys the raft.

Prescribing in practice

Each dose carries a notable sodium load from the bicarbonate and alginate, so use with caution in patients on a restricted-sodium diet or with heart failure, hypertension or significant renal impairment.
Take after meals and at bedtime, and separate dosing from other oral medicines as the raft and the antacid component can reduce absorption of concurrently administered drugs.
Persistent, worsening or alarm symptoms (dysphagia, weight loss, gastrointestinal bleeding) warrant investigation rather than continued self-treatment.

Monitoring

Routine laboratory monitoring is not required, but review symptom control and reconsider the diagnosis if reflux symptoms persist despite regular use.

Counselling the patient

Take after meals and at bedtime for best effect on reflux.
Leave a gap before or after other tablets to avoid reducing their absorption.
See your prescriber if symptoms persist, worsen, or you have difficulty swallowing.

Evidence & guidelines

Raft-forming alginate preparations are recommended in NICE guidance as an option for the symptomatic management of dyspepsia and gastro-oesophageal reflux.

Reference: NICE CG184; RCOG; 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