Aluminium Hydroxide Properties: What You Need to Know

When working with Aluminium hydroxide, a white, water‑insoluble powder used as an antacid and phosphate binder. Also known as Al(OH)₃, it neutralizes stomach acid and captures excess phosphate in kidney patients.

Antacid action is the most familiar side of aluminium hydroxide. By reacting with hydrochloric acid in the stomach, it forms aluminum chloride and water, raising the pH and easing heartburn. The same neutralization reaction also reduces gastric acid, which helps protect the lining of the stomach and duodenum. Because it is practically insoluble, most of the compound stays in the gut, limiting systemic absorption. This low absorption is why aluminium hydroxide is also classified as a phosphate binder: in patients with chronic kidney disease, it binds dietary phosphate, forming an insoluble complex that is excreted in the stool. The dual role makes it a valuable tool for both over‑the‑counter heartburn relief and prescription‑only renal therapy.

Key Characteristics and Common Pairings

From a chemical standpoint, aluminium hydroxide has the formula Al(OH)₃ and appears as a fine, white powder. Its solubility in water is less than 0.01 g/L at room temperature, which means it doesn’t dissolve readily in the stomach’s acidic environment. This property gives it a slow, sustained buffering effect, unlike fast‑acting agents that may cause a rapid pH jump. When combined with magnesium hydroxide, the two create a balanced antacid mixture often marketed as “Maalox” or “Mylanta.” The magnesium component counters the constipation that pure aluminium compounds can cause, while the aluminium component reduces the diarrhea risk from magnesium alone. This synergy illustrates a classic example of how two related entities can complement each other to improve patient comfort.

Beyond its buffering capacity, aluminium hydroxide’s low systemic uptake influences its safety profile. Because little of the compound crosses the gut wall, side effects are usually limited to the digestive tract: mild constipation, occasional nausea, and a chalky taste. In renal patients, long‑term use may lead to aluminum accumulation, potentially causing bone disease or neurotoxicity, which is why clinicians monitor serum aluminum levels and often alternate with other binders. The dosage form also matters: tablets, chewables, and liquid suspensions each provide different onset times and patient convenience, shaping how the drug fits into daily routines.

Understanding these properties helps answer common questions: why does aluminium hydroxide sometimes make you feel full? why is it paired with magnesium in many over‑the‑counter products? and how does it differ from other antacids like calcium carbonate? The answers lie in its low solubility, dual action as a phosphate binder, and need for balanced formulations. By linking the chemical traits to practical outcomes, we see a clear chain: the compound’s insolubility → sustained acid neutralization → reduced heartburn and phosphate absorption → specific safety considerations.

Below you’ll find a curated list of articles that dive deeper into related topics, from the side‑effects of various drugs to the way antacids interact with other medications. Whether you’re looking for detailed mechanisms, dosage advice, or comparisons with alternatives, the collection offers practical insights that build on the basics covered here.