Aluminium Hydroxide + Carboxymethylcellulose + Dimethicone (Simethicone) + Magnesium Hydroxide is a combination antacid medication that is used to relieve heartburn, acid indigestion, sour stomach, and bloating associated with excess stomach acid and/or trapped gas. It contains aluminium hydroxide and magnesium hydroxide, two complementary antacids that neutralise gastric acid; carboxymethylcellulose, a viscous polymer that coats and protects the mucosal surface and dimethicone (simethicone), an anti-foaming agent that breaks down trapped gas bubbles in the stomach and intestine. Together, the four components provide rapid acid neutralisation, mucosal protection, and relief from gas-related discomfort.

Heartburn, acid reflux, indigestion, and bloating are among the most common gastrointestinal complaints seen in primary care. They typically arise from excess gastric acid, weakened lower oesophageal sphincter function, slow gastric emptying, or trapped gas in the stomach and bowel. Symptoms include a burning sensation behind the breastbone, sour taste, belching, abdominal fullness, and discomfort that often worsens after large or rich meals, when lying down, or during bending. While most episodes are short-lived and respond well to antacid therapy, persistent symptoms warrant medical assessment to exclude underlying conditions such as gastritis, peptic ulcer disease, hiatus hernia, or, rarely, malignancy.

Aluminium hydroxide is a slow-acting antacid that reacts with hydrochloric acid in the stomach to form aluminium chloride and water, raising gastric pH and reducing acid-related symptoms. Aluminium-based antacids tend to cause constipation, which is why they are often paired with a magnesium salt.

Magnesium hydroxide is a faster-acting antacid that neutralises gastric acid more quickly and also has a mild laxative effect, which balances the constipating tendency of aluminium hydroxide. Together, the two antacids provide both rapid and sustained acid neutralisation with balanced effects on bowel function.

Carboxymethylcellulose (CMC) is a high-molecular-weight cellulose derivative that swells in water to form a viscous, gel-like solution. In an antacid preparation, it provides a coating effect on the mucosal lining of the oesophagus and stomach, helping to physically buffer the surface against acid and providing a 'soothing' sensation. It can also help retain antacid components at the mucosal surface for longer.

Dimethicone (simethicone) is a silicone-based anti-foaming agent. It reduces the surface tension of gas bubbles in the gastrointestinal tract, causing them to coalesce into larger bubbles that can be more easily passed by belching or as flatus. Simethicone is not absorbed and acts purely by mechanical means on gas bubbles.

The combination is widely used for symptomatic relief of acid-related dyspepsia and bloating, and is generally well tolerated in short courses.

• Symptomatic relief of heartburn, acid indigestion, and sour stomach.

• Relief of bloating and discomfort caused by trapped gas in the stomach and intestines.

• Adjunctive symptomatic management of gastritis and gastro-oesophageal reflux disease (GERD) under medical advice.

• Relief of dyspeptic symptoms after large or rich meals.

• Adjunct in peptic ulcer disease, when prescribed alongside specific acid-suppressing therapy.

• Rapid relief of acid-related symptoms through magnesium hydroxide combined with slower, sustained action from aluminium hydroxide.

• Balanced bowel effects, as the constipating tendency of aluminium and the laxative tendency of magnesium offset each other.

• Carboxymethylcellulose provides a soothing mucosal coating that complements the antacid effect.

• Simethicone addresses bloating and gas-related discomfort, which antacids alone do not relieve.

• Multi-component formulation addresses several common dyspepsia symptoms in a single preparation.

Common

• Mild constipation (more often from aluminium)
• Mild diarrhoea or loose stools (more often from magnesium)
• Belching
• Chalky taste

Uncommon

• Nausea
• Abdominal cramping
• Mild bloating

Serious side effects requiring immediate attention

• Severe allergic reaction, which may manifest as rash, swelling, and/or breathing difficulty
• Signs of electrolyte disturbance with long-term high-dose use may result in muscle weakness, confusion, and irregular heartbeat
• Aluminium accumulation with prolonged use in patients with chronic kidney disease may result in bone disease and neurological symptoms
• Worsening renal function in those with pre-existing kidney disease
• Persistent or worsening abdominal pain, black stools, or blood in vomit (consult a doctor)

Take Aluminium Hydroxide + Carboxymethylcellulose + Dimethicone (Simethicone) + Magnesium Hydroxide orally as directed by your doctor or pharmacist, usually between meals and at bedtime when acid-related symptoms are most troublesome. Shake the bottle well if it is a suspension, and measure the dose with the supplied cup or spoon. For tablet forms, chew thoroughly before swallowing and follow with a small amount of water. Do not exceed the recommended daily dose. Avoid taking other medicines within 2 hours of Aluminium Hydroxide + Carboxymethylcellulose + Dimethicone (Simethicone) + Magnesium Hydroxide, as antacids can interfere with the absorption of many drugs. If your symptoms persist for more than 2 weeks or worsen at any point, consult a doctor, as this product is intended for short-term symptomatic relief, not long-term self-treatment of undiagnosed disease.

Aluminium hydroxide and magnesium hydroxide work through a straightforward acid–base reaction. Research shows that these weak bases react with hydrochloric acid in the stomach to form water and the corresponding salts (aluminium chloride and magnesium chloride), thereby raising gastric pH from its normal range of 1–2 towards a less corrosive level. This reduces the irritant effect of acid on the oesophageal and gastric lining and lowers the symptoms such as burning, sour taste, and discomfort. While magnesium hydroxide acts within minutes, aluminium hydroxide slower than that but provides more sustained buffering.

The two antacids are deliberately combined because their gastrointestinal side effects offset each other. Aluminium ions slow intestinal motility and cause constipation, while magnesium ions draw water into the bowel and have a mild laxative effect.

Carboxymethylcellulose is a long-chain cellulose derivative that swells in water to form a viscous gel. In the upper gastrointestinal tract, it forms a coating layer over the mucosa, creating a physical barrier that reduces direct acid contact with already irritated tissue. This helps in providing immediate relief to effect many patients described with such combinations.

Simethicone (dimethicone) is a silicone polymer that acts on the foam of gas bubbles trapped in the stomach and intestine. By lowering the surface tension of these bubbles, they cause them to merge into larger bubbles that are more easily passed upward as a belch or downward as flatus. Simethicone is not absorbed into the bloodstream but acts mechanically and is excreted unchanged.

Together, the four components address acid, mucosal irritation, and gas in a single preparation.

• Citrus juices (CAUTION): Can increase aluminium absorption.

• Dairy products (CAUTION): When combined with high doses of magnesium or aluminium hydroxide, may contribute to the rarely seen milk-alkali syndrome (triad of increased calcium levels, metabolic alkalosis, and acute kidney injury) with calcium supplements.

• Alcohol (CAUTION): Can worsen acid reflux and mucosal irritation.

• Large or fatty meals (CAUTION): The symptoms may come back even after taking the medication. Lifestyle modification is helpful along with antacid therapy.

• Tetracyclines, fluoroquinolones (SEVERE): Aluminium and magnesium bind these antibiotics, dramatically reducing their absorption. Separate by 2–4 hours.

• Iron supplements (SEVERE): Antacids reduce iron absorption. Separate both by at least 2 hours.

• Bisphosphonates (SEVERE): Antacids markedly reduce absorption. Take the bisphosphonate first thing in the morning and the antacid much later.

• Levothyroxine (SEVERE): Antacids reduce levothyroxine absorption; separate by at least 4 hours.

• Digoxin (CAUTION): Antacids can reduce digoxin absorption; separate dosing.

• Some HIV antiretrovirals (e.g., atazanavir, rilpivirine) (SEVERE): Antacids can significantly reduce absorption; consult your prescriber for timing.

• Proton pump inhibitors and H2 blockers (CAUTION): Antacids can be used alongside, but timing may matter for some PPIs; check with your pharmacist.

• Polystyrene sulfonate resins (CAUTION): Antacids may interact and reduce efficacy.

• Chronic kidney disease (CAUTION): Aluminium can accumulate and contribute to bone disease and neurological effects, while magnesium can accumulate, causing hypermagnesaemia (high magnesium levels in the blood).

• Heart failure on sodium- or fluid-restricted regimens (CAUTION): Some antacid preparations contain sodium. Check the label before use.

• Constipation or bowel obstruction (CAUTION): Aluminium-containing antacids can worsen constipation.

• Diarrhoea or inflammatory bowel disease (CAUTION): Magnesium-containing antacids can worsen diarrhoea.

• Suspected gastrointestinal bleeding, persistent vomiting, unintended weight loss (CONSULT YOUR DOCTOR): These features require investigation, not self-medication.

• Phenylketonuria (CAUTION): Some chewable formulations may contain aspartame.

Acute overdose is uncommon but can cause significant gastrointestinal upset, electrolyte disturbance (especially hypermagnesaemia with symptoms such as muscle weakness, low blood pressure, slow heartbeat, and confusion), and aluminium accumulation in those with reduced kidney function. Long-term excessive use can lead to phosphate depletion (with bone pain and weakness) and aluminium-related neurological and bone disease in chronic kidney disease. Seek medical advice for a significant overdose, particularly in patients with renal impairment.

If you forget a dose, take it when symptoms occur or as soon as you remember. If your symptoms have already settled, you can simply skip the missed dose. Do not take a double dose.