Aluminium Hydroxide (Antacid) — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Aluminium Hydroxide (Antacid)?
Aluminium hydroxide is an antacid used to neutralise stomach acid and treat symptoms of gastric and duodenal ulcers, GERD, and hyperacidity. This medication is available over-the-counter; some formulations funded by Pharmac.
What is Aluminium Hydroxide (Antacid) Used For?
Aluminium hydroxide is used for the symptomatic relief of heartburn, acid indigestion, gastro-oesophageal reflux, and as part of combination antacids (with magnesium hydroxide — Mylanta®) for peptic ulcer disease. In dialysis patients, it is also used as a phosphate binder.
How Does Aluminium Hydroxide (Antacid) Work?
Aluminium hydroxide is a weak base that reacts with gastric hydrochloric acid to form aluminium chloride and water, neutralising stomach acid and raising gastric pH. This reduces acid-related symptoms. In renal failure, aluminium hydroxide binds dietary phosphate in the gut, reducing its absorption.
How to Take Aluminium Hydroxide (Antacid)
For antacid: 1–2 tablets or 10–20 mL of suspension, 20–60 minutes after meals and at bedtime. Separate from other medicines by at least 2 hours as antacids reduce absorption of many drugs. Do not use for extended periods without medical review.
Common Side Effects of Aluminium Hydroxide (Antacid)
- Constipation (characteristic of aluminium antacids)
- Chalky taste
- Nausea
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Aluminium accumulation (with prolonged use in renal impairment — encephalopathy, dialysis dementia)
- Hypophosphataemia (phosphate depletion with prolonged high-dose use in patients with normal phosphate)
Drug Interactions
Aluminium Hydroxide (Antacid) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Many medicines: reduces absorption of fluoroquinolones, tetracyclines, levothyroxine, digoxin, azithromycin, iron, and many others — take other medicines at least 2 hours before antacids
New Zealand Prescribing Information
Aluminium hydroxide/magnesium hydroxide combinations (Mylanta® tablets and suspension) are available over-the-counter at NZ pharmacies. For GERD or peptic ulcer disease, PPI-based therapy is more effective and appropriate for recurrent symptoms. Antacids are suitable for occasional breakthrough heartburn relief. Aluminium-based antacids should generally be avoided in renal impairment due to aluminium accumulation risk.
Frequently Asked Questions
Can I take an antacid with my other medicines?
Antacids significantly reduce the absorption of many medicines including antibiotics (fluoroquinolones, tetracyclines), levothyroxine, iron, and others. Always take other medicines at least 2 hours before an antacid dose. Tell your pharmacist you take antacids when any new medicine is dispensed.
Are antacids the same as proton pump inhibitors?
No — antacids neutralise acid that is already in the stomach, providing quick relief but with a short duration (30–60 minutes). PPIs (omeprazole, lansoprazole) block acid production at its source, providing more sustained and powerful acid suppression. PPIs are more appropriate for persistent GERD or ulcer treatment.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: