Gaviscon (Sodium Alginate)
Alginate-based reflux suppressant for heartburn and acid reflux
Quick Facts About Gaviscon
Key Takeaways About Gaviscon
- Unique mechanism of action: Unlike traditional antacids, Gaviscon forms a physical raft barrier on top of stomach contents to prevent acid reflux into the esophagus
- Fast-acting relief: Gaviscon typically begins working within 3-4 minutes and can provide relief lasting up to 4 hours
- Safe in pregnancy: No adverse effects on the fetus have been demonstrated, making it a first-line option for pregnancy-related heartburn
- Mind drug interactions: Take Gaviscon at least 2 hours apart from iron supplements, antibiotics, and thyroid medications to avoid reduced absorption
- See a doctor if symptoms persist: If heartburn continues beyond 7 days of self-treatment, consult a healthcare provider to rule out more serious conditions
What Is Gaviscon and What Is It Used For?
Gaviscon is an over-the-counter alginate-based medicine used to treat heartburn and acid reflux. It forms a gel-like raft on top of the stomach contents that acts as a physical barrier, preventing acidic material from refluxing into the esophagus.
Gaviscon contains sodium alginate as its primary active ingredient, along with sodium bicarbonate, aluminium hydroxide, and calcium carbonate. When the sodium alginate comes into contact with gastric acid, it undergoes a chemical reaction that produces a low-density viscous gel known as an "alginate raft." This raft floats on top of the stomach contents and physically prevents the acidic gastric material from being pushed back up into the esophagus during episodes of gastro-esophageal reflux.
The additional antacid components — sodium bicarbonate, aluminium hydroxide, and calcium carbonate — provide supplementary acid-neutralizing capacity. They help raise the pH of the stomach contents directly beneath the raft, further reducing the acidity of any material that might reflux despite the raft barrier. This dual mechanism of physical barrier plus chemical neutralization distinguishes Gaviscon from simple antacid preparations.
Gaviscon is primarily indicated for the symptomatic relief of heartburn and acid reflux. Heartburn is a burning sensation behind the breastbone caused by stomach acid irritating the lining of the esophagus. It commonly occurs after meals, when bending over, or when lying down. Acid reflux refers to the backward flow of stomach contents into the esophagus, which can cause heartburn as well as a sour taste in the mouth and regurgitation.
In addition to over-the-counter self-medication, Gaviscon may be prescribed by a physician for the management of reflux esophagitis (inflammation of the esophageal lining caused by chronic acid exposure) and hiatal hernia (a condition where part of the stomach pushes up through the diaphragm, which can worsen reflux symptoms). In these clinical settings, Gaviscon is often used as an adjunct to proton pump inhibitors (PPIs) or H2 receptor antagonists.
You should see a healthcare provider if your symptoms do not improve or worsen after 7 days of self-treatment, if you experience difficulty swallowing, unintended weight loss, persistent vomiting, or if you are over 55 years old with new-onset heartburn. These symptoms may indicate a more serious underlying condition that requires medical investigation.
What Should You Know Before Taking Gaviscon?
Before taking Gaviscon, check that you are not allergic to any of its ingredients. Patients with severe kidney impairment should consult a physician first. Gaviscon contains sodium, which is relevant for people on sodium-restricted diets.
Contraindications
Do not use Gaviscon if you are allergic (hypersensitive) to any of its active substances or excipients. The active ingredients include sodium alginate, sodium bicarbonate, aluminium hydroxide, and calcium carbonate. Notable excipients include methylparaben (E218) and propylparaben (E216), which are preservatives that can cause allergic reactions in susceptible individuals, sometimes with a delayed onset.
There are no absolute contraindications beyond hypersensitivity. However, several situations require caution or medical advice before use, particularly in patients with impaired renal function.
Warnings and Precautions
Consult your doctor or pharmacist before using Gaviscon if you have severely impaired kidney function. The aluminium hydroxide component is primarily eliminated by the kidneys, and accumulation may occur in patients with renal insufficiency. Chronic aluminium exposure in patients with renal failure has been associated with aluminium-related bone disease (osteomalacia) and, in rare cases, encephalopathy.
Gaviscon contains a significant amount of sodium. Each dose of 10–20 ml provides approximately 100–200 mg of sodium, which corresponds to 5–10% of the maximum recommended daily sodium intake for adults (2,000 mg per WHO guidelines). If you need to take 40 ml or more daily for an extended period, particularly if you have been advised to follow a low-sodium diet, consult your healthcare provider. This is especially important for patients with heart failure, hypertension, or chronic kidney disease.
The preservatives methylparaben (E218) and propylparaben (E216) may cause allergic reactions in some individuals. These reactions can be delayed, so if you develop a skin rash or other signs of allergy after starting Gaviscon, discontinue use and consult your doctor.
Each 10–20 ml dose contains 100–200 mg sodium (5–10% of WHO-recommended daily maximum). Consult a healthcare provider before long-term use if you are on a sodium-restricted diet, have heart failure, or have kidney disease.
Pregnancy and Breastfeeding
Gaviscon is generally considered safe during both pregnancy and breastfeeding. No adverse effects on the fetus have been demonstrated in clinical experience or available studies. The alginate-based mechanism of action is primarily physical rather than systemic, meaning that very little of the active ingredients are absorbed into the bloodstream.
Gaviscon does not pass into breast milk, making it suitable for use by breastfeeding mothers. For these reasons, Gaviscon is one of the most commonly recommended first-line treatments for heartburn during pregnancy, which affects up to 80% of pregnant women, particularly in the second and third trimesters.
Despite its favorable safety profile, it is always advisable to consult your midwife, obstetrician, or general practitioner before starting any medication during pregnancy. They can confirm that Gaviscon is appropriate for your individual circumstances and suggest the optimal dosing regimen.
Food and Drink
Gaviscon should not be taken with fruit juice. Acidic juices can interfere with the formation of the alginate raft, potentially reducing the effectiveness of the medicine. Take Gaviscon with a small amount of water if needed to wash it down.
Driving and Operating Machinery
Gaviscon has no known effect on the ability to drive or operate machinery. It does not cause drowsiness, dizziness, or any central nervous system effects that would impair cognitive or motor function.
How Does Gaviscon Interact with Other Drugs?
Gaviscon can reduce the absorption of several medications when taken at the same time. As a general rule, take Gaviscon at least 2 hours apart from other medications, particularly iron supplements, certain antibiotics, thyroid hormones, and bisphosphonates.
Because Gaviscon contains antacid components (aluminium hydroxide and calcium carbonate), it can interfere with the absorption of various medications. The antacids can bind to drug molecules in the gastrointestinal tract, reduce gastric pH changes needed for drug dissolution, or alter the rate at which medications are absorbed. Below is a comprehensive overview of the most clinically significant interactions.
Major Interactions
The following interactions are considered clinically significant and require careful timing of doses. In all cases, take the interacting medication at least 2 hours before or after Gaviscon:
| Drug / Drug Class | Used For | Interaction Effect | Recommendation |
|---|---|---|---|
| Iron supplements | Iron deficiency anemia | Significantly reduced iron absorption due to binding with aluminium/calcium | Take at least 2 hours apart |
| Tetracyclines (e.g., doxycycline) | Bacterial infections | Chelation with aluminium and calcium reduces antibiotic absorption by up to 90% | Take at least 2–3 hours apart |
| Fluoroquinolones (e.g., ciprofloxacin) | Bacterial infections | Chelation with metal ions reduces antibiotic bioavailability significantly | Take at least 2 hours apart |
| Thyroid hormones (levothyroxine) | Hypothyroidism | Reduced absorption leading to subtherapeutic thyroid hormone levels | Take levothyroxine 4 hours before or after |
| Bisphosphonates (e.g., alendronate) | Osteoporosis | Markedly reduced bisphosphonate absorption | Take bisphosphonate first, wait at least 30 min before food/other drugs |
| Mycophenolate mofetil | Organ transplant rejection | Reduced mycophenolate absorption, risk of transplant rejection | Take at least 2 hours apart; monitor drug levels |
Minor Interactions
The following interactions are less commonly encountered but should still be considered. These medications may have reduced effectiveness when taken simultaneously with Gaviscon:
| Drug / Drug Class | Used For | Recommendation |
|---|---|---|
| Ketoconazole | Fungal infections | Take at least 2 hours apart; ketoconazole needs acidic pH for absorption |
| Sotalol | Irregular heart rhythm | Take at least 2 hours apart |
| Gabapentin | Epilepsy, nerve pain | Take gabapentin at least 2 hours after antacids |
| Estramustine | Prostate cancer | Avoid concurrent use; calcium binds estramustine |
| Ursodeoxycholic acid | Gallstones | Take at least 2 hours apart |
| Diflunisal | Pain, inflammation | Take at least 2 hours apart |
If you are taking any other medication, the simplest approach is to take Gaviscon at least 2 hours apart from all other medicines. Always inform your doctor or pharmacist about all medications, supplements, and herbal products you are using.
What Is the Correct Dosage of Gaviscon?
The standard adult dose of Gaviscon is 10–20 ml of oral suspension, taken approximately 30 minutes after meals, at bedtime, and as needed. Shake the bottle well before each use. Do not drink directly from the bottle.
Always use Gaviscon exactly as described in the patient information leaflet or as directed by your doctor or pharmacist. The suspension should be thoroughly shaken before each use to ensure a homogeneous mixture of the active ingredients. If needed, the dose may be washed down with a small amount of water.
Adults
Standard Adult Dosage
Dose: 10–20 ml (equivalent to 2–4 teaspoons) of oral suspension
When to take: Approximately 30 minutes after meals, just before bedtime, and as needed for breakthrough symptoms
Maximum frequency: Up to 4 times daily (after each of 3 meals plus bedtime)
Maximum daily dose: 80 ml (4 doses of 20 ml)
Most patients find that 10 ml is sufficient for mild heartburn, while 20 ml may be necessary for more severe symptoms or larger meals. The timing of the dose is important — taking Gaviscon approximately 30 minutes after eating allows the alginate raft to form on top of the meal in the stomach, providing the most effective barrier against postprandial reflux.
Children
Paediatric Dosage
Gaviscon oral suspension is generally intended for adults and adolescents. For children under 12 years of age, always consult a healthcare provider before use. Specialised paediatric formulations of Gaviscon (such as Gaviscon Infant) are available in some countries for infants with reflux, but these have different compositions and dosing instructions.
Elderly
Elderly Patients
No dose adjustment is generally required for elderly patients. However, elderly patients are more likely to have impaired kidney function and may be on sodium-restricted diets. If you are over 65 years old and plan to use Gaviscon regularly, discuss this with your doctor to ensure it is appropriate given your overall medication regimen and health status.
Missed Dose
Gaviscon is taken on an as-needed basis rather than on a strict schedule. If you forget a dose, simply take it when you next experience symptoms. Do not take a double dose to compensate for a missed one. Since Gaviscon works by forming a physical barrier rather than building up a blood concentration, missed doses do not have the same implications as with many other medications.
Overdose
If a significantly larger amount of Gaviscon has been taken than recommended, or if a child has accidentally ingested the medicine, contact a doctor, hospital emergency department, or your local poison control centre for assessment and advice. While serious toxicity from Gaviscon overdose is very unlikely due to its low systemic absorption, large doses of the antacid components (particularly aluminium hydroxide) could potentially cause gastrointestinal symptoms such as constipation, bloating, or nausea.
In the event of significant sodium or aluminium ingestion, patients with pre-existing renal impairment may be at greater risk and should seek medical evaluation promptly.
What Are the Side Effects of Gaviscon?
Gaviscon is generally very well tolerated. Side effects are rare and mostly mild. Isolated reports of skin rash, itching, and fluid retention have been reported, though a direct causal link to Gaviscon has not been established.
Like all medicines, Gaviscon can cause side effects, although not everybody experiences them. The alginate-based mechanism means that most of the active ingredients act locally in the gastrointestinal tract with minimal systemic absorption, which accounts for the very favorable side effect profile compared to many other gastrointestinal medications.
The side effects reported in clinical practice and post-marketing surveillance are listed below, categorized by frequency according to the standard Medical Dictionary for Regulatory Activities (MedDRA) convention:
Uncommon Side Effects
May affect up to 1 in 100 people
- Bloating or feeling of fullness
- Mild nausea
Rare Side Effects
May affect up to 1 in 1,000 people
- Skin rash (isolated reports, causal link not established)
- Itching (pruritus)
- Mild fluid retention (edema) in tissues
It is important to note that the skin rash, itching, and fluid retention reported in isolated cases have not been definitively linked to Gaviscon. These may be coincidental findings or related to the preservatives (parabens) present in the formulation rather than the active ingredients themselves.
Patients who take high doses of Gaviscon over prolonged periods should be aware that the aluminium hydroxide component can occasionally cause constipation, while the sodium content may contribute to fluid retention in susceptible individuals. The calcium carbonate component may rarely cause hypercalcemia (elevated blood calcium) with chronic excessive use, though this is extremely unlikely at recommended doses.
If you experience any side effects, including possible side effects not listed here, talk to your doctor or pharmacist. You can also report side effects directly to your national medicines regulatory agency (e.g., FDA MedWatch in the US, MHRA Yellow Card in the UK, EMA in the EU). By reporting side effects, you help provide more information on the safety of this medicine.
How Should You Store Gaviscon?
Store Gaviscon at or below 25°C (77°F), protected from cold. Keep the bottle tightly closed. Do not use after the expiry date on the bottle. Keep out of the reach and sight of children.
Proper storage of Gaviscon is essential to maintain the quality and effectiveness of the suspension. The following guidelines should be followed:
- Temperature: Store at or below 25°C (77°F). Do not freeze the suspension, as this can damage the alginate formulation and affect the ability of the product to form an effective raft.
- Light and moisture: Keep the bottle tightly closed when not in use. There are no specific light-sensitivity precautions, but keeping the cap secure prevents contamination and evaporation.
- Expiry date: Do not use Gaviscon after the expiry date printed on the bottle. The expiry date refers to the last day of the indicated month.
- Children: Keep this medicine out of the sight and reach of children at all times.
- Disposal: Do not dispose of medicines via household waste or wastewater. Return unused medicines to your local pharmacy for safe disposal. This helps protect the environment.
Once opened, the oral suspension should be used within the shelf life indicated on the bottle. If you notice any changes in the appearance, color, or smell of the suspension, do not use it. While some separation of the suspension is normal and can be resolved by shaking, any unusual clumping, discoloration, or off-odor indicates that the product should be discarded.
What Does Gaviscon Contain?
Gaviscon contains four active ingredients: sodium alginate (50 mg/ml), sodium bicarbonate (17 mg/ml), aluminium hydroxide (15 mg/ml), and calcium carbonate (15 mg/ml), along with several inactive excipients.
Active Ingredients
Each milliliter of Gaviscon oral suspension contains:
- Sodium alginate 50 mg/ml — the primary active ingredient that forms the alginate raft
- Sodium bicarbonate 17 mg/ml — reacts with gastric acid to produce carbon dioxide, which helps the raft float
- Aluminium hydroxide 15 mg/ml — provides acid-neutralizing capacity
- Calcium carbonate 15 mg/ml — provides additional acid-neutralizing capacity and helps strengthen the raft
Inactive Ingredients (Excipients)
The suspension also contains the following inactive ingredients:
- Methylparaben (E218) — preservative (may cause allergic reactions in susceptible individuals)
- Propylparaben (E216) — preservative (may cause allergic reactions in susceptible individuals)
- Xanthan gum — thickening and stabilizing agent
- Colloidal anhydrous silica — anti-caking agent
- Saccharin sodium — artificial sweetener
- Flavoring agents — lemon, raspberry, and vanilla flavors
- Purified water — vehicle/solvent
Appearance and Packaging
Gaviscon oral suspension is a white to yellowish suspension supplied in plastic bottles. It is available in several sizes: 100 ml, 200 ml, 400 ml, and 500 ml. Not all pack sizes may be marketed in all countries. The product should be shaken well before use to ensure uniform distribution of the active ingredients.
Frequently Asked Questions About Gaviscon
While regular antacids (like Tums or Rennie) work solely by chemically neutralizing stomach acid, Gaviscon has a unique dual mechanism. Its primary action is physical: the sodium alginate reacts with stomach acid to form a gel-like raft that floats on top of the stomach contents, creating a physical barrier against reflux. It also contains antacid components that provide supplementary acid neutralization. This means Gaviscon is particularly effective for reflux symptoms, while traditional antacids are more suited for general stomach acidity without significant reflux.
Gaviscon typically begins to work within 3 to 4 minutes after ingestion. The alginate raft forms rapidly upon contact with gastric acid, providing an almost immediate physical barrier against acid reflux. Relief from heartburn symptoms can last for up to 4 hours depending on the dose and individual factors such as stomach contents and body position.
Yes, Gaviscon is generally considered safe during pregnancy and is one of the most commonly recommended first-line treatments for pregnancy-related heartburn. No adverse effects on the fetus have been demonstrated. The alginate-based mechanism is primarily physical and local, with minimal systemic absorption. Additionally, Gaviscon does not pass into breast milk. However, always consult your healthcare provider before starting any medication during pregnancy to confirm it is appropriate for your individual situation.
Yes, Gaviscon can be taken alongside proton pump inhibitors (PPIs) such as omeprazole, lansoprazole, or esomeprazole. In fact, this combination is often clinically beneficial. PPIs reduce overall acid production, while Gaviscon provides an additional physical barrier against reflux. Research published in Alimentary Pharmacology & Therapeutics has shown that adding an alginate-based product to PPI therapy can improve symptom control in patients with persistent reflux. However, take Gaviscon at least 2 hours apart from your PPI to avoid any interference with PPI absorption.
For occasional use, Gaviscon has an excellent safety profile. However, for self-medication, it should not be used for more than 7 consecutive days without consulting a healthcare provider. If your doctor prescribes Gaviscon for a diagnosed condition such as GERD or reflux esophagitis, longer-term use may be appropriate under medical supervision. Long-term considerations include sodium intake (relevant for patients with hypertension or heart failure) and aluminium accumulation (primarily a concern in patients with impaired kidney function).
Fruit juice, particularly citrus juices, has an acidic pH that can interfere with the formation of the alginate raft in the stomach. For the raft to form optimally, the sodium alginate needs to react with the hydrochloric acid in the stomach under specific pH conditions. Adding external acid from juice may alter this process and reduce the effectiveness of the barrier. For best results, take Gaviscon with a small amount of plain water if needed.
References
This article is based on the following peer-reviewed sources and international medical guidelines:
- European Medicines Agency (EMA). Alginate-based reflux suppressants – Summary of Product Characteristics. Available at: ema.europa.eu
- British National Formulary (BNF). Sodium alginate with calcium carbonate – Drug monograph. Available at: bnf.nice.org.uk
- National Institute for Health and Care Excellence (NICE). Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management. Clinical guideline [CG184]. 2014, updated 2019.
- Leiman DA, Riff BP, Morgan S, et al. Alginate therapy is effective treatment for GERD symptoms: a systematic review and meta-analysis. Diseases of the Esophagus. 2017;30(5):1–9. doi:10.1093/dote/dow020
- Rohof WO, Bennink RJ, Smout AJ, Thomas E, Boeckxstaens GE. An alginate-antacid formulation localizes to the acid pocket to reduce acid reflux in patients with gastroesophageal reflux disease. Clinical Gastroenterology and Hepatology. 2013;11(12):1585–1591.
- World Health Organization (WHO). Guidelines on sodium intake for adults and children. Geneva: WHO; 2012.
- Strugala V, Avis J, Buxton IR, et al. The role of an alginate suspension on pepsin and bile acids. International Journal of Pharmaceutics. 2009;377(1–2):135–141.
- Mandel KG, Daggy BP, Brodie DA, Jacoby HI. Review article: alginate-raft formulations in the treatment of heartburn and acid reflux. Alimentary Pharmacology & Therapeutics. 2000;14(6):669–690.
About the Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, comprising licensed physicians specializing in gastroenterology, clinical pharmacology, and general internal medicine. All medical content follows the GRADE evidence framework and adheres to international guidelines from the EMA, NICE, BNF, and WHO.