Aluminum hydroxide


In the medical and health sector, aluminum hydroxide Al (OH) 3 is known for its ability to neutralize excessive gastric acidity and reduce the absorption of phosphorus in patients suffering from renal insufficiency. Aluminum hydroxide also reduces the reabsorption of bile acids, but in this sense it has been supplanted by the more effective and safe cholestyramine.

Use as an antacid

In contact with the hydrochloric acid produced by the parietal cells of the gastric mucosa, the aluminum hydroxide reacts by reducing the acidity of the acid content of the stomach, as shown by the following reaction:

Al (OH) 3 + 3 HCl -> AlCl3 + 3 H2O

Although in this sense it is less effective than other antacids, such as sodium bicarbonate, magnesium hydroxide and calcium carbonate, aluminum hydroxide can give relief from the symptoms of gastric hyperacidity, being useful in the presence of ulcers, gastritis and reflux. gastroesophageal.

Generally, in common antacid drugs, aluminum hydroxide is associated with other salts with both antacid and laxative effect, in order to neutralize the constipating effect. If used alone as an antacid, aluminum hydroxide can in fact cause constipation; among the most common associations we remember that between aluminum hydroxide and magnesium hydroxide (typical of Maalox ®) and that between aluminum hydroxide and magnesium carbonate.


  • the medicine can have an astringent effect and cause constipation; at high doses it can be responsible for intestinal obstruction
  • In case of hypophosphatemia or low phosphorus diets, keep in mind that aluminum hydroxide can cause phosphorus deficiency by decreasing intestinal absorption.
  • In patients with severe renal insufficiency, plasma levels of aluminum tend to increase. In these patients, long exposures to high doses of aluminum can lead to encephalopathies or worsening of dialysis osteomalacia.
  • Aluminum hydroxide may not be safe in patients with porphyria undergoing hemodialysis.
  • In the presence of severe renal insufficiency it is recommended to take the product under the direct supervision of a doctor. Prolonged use of the medicinal product should be avoided in these patients.
  • it is recommended to avoid the intake of aluminum hydroxide during oral tetracycline therapies (it reduces its gastrointestinal absorption)
  • The use of aluminum-containing antacids may reduce the absorption of H2-antagonists, atenolol, chloroquine, tetracyclines, diflunisal, digoxine, bisphosphonates, ethambutol, fluoroquinolones, sodium fluoride, glucocorticoids, indomethacin, isoniazid, kayexalate, ketoprincosphonates, , phenothiazine neuroleptics, penicillamines, propranolol, iron salts.
  • Leave at least two hours (4 for fluoroquinolones) between the intake of other drugs and that of aluminum hydroxide, in order to avoid drug interactions.
  • The simultaneous use of aluminum hydroxide and citrates can lead to an increase in aluminum levels, particularly in patients with renal insufficiency.
  • The intake of aluminum hydroxide can give the stool a chalky white color

Used to reduce phosphorus absorption

Once in the stomach, the aluminum hydroxide is able to bind to phosphorus sequestrating it and preventing its intestinal absorption; this feature may be particularly useful for patients with advanced kidney disease, often suffering from hyperphosphatemia.

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