BMA Concise Guide to Medicine & Drugs

Aluminium Hydroxide

Brand name Alu-Cap

Used in the following combined preparations Algicon, Aludrox, Asilone, Co-magaldrox, Maalox, Mucogel, Topal, and others


Drug group Antacid

Overdose danger rating Low

Dependence rating Low

Prescription needed No

Available as generic Yes


Aluminium hydroxide is a common ingredient of many over-the-counter remedies for indigestion and heartburn. Because the drug is constipating (it is sometimes used to treat diarrhoea), it is usually combined with a magnesium-containing antacid with a balancing laxative effect. The combination is sometimes referred to by the generic name of co-magaldrox.

The prolonged action of the drug makes it useful in preventing the pain of stomach and duodenal ulcers or heartburn. Aluminium hydroxide can also promote the healing of ulcers.

The drug may be more effective as an antacid in liquid form rather than as tablets. Some antacid preparations include large amounts of sodium and these should be used with caution by those on low-sodium diets.

In the intestine, aluminium hydroxide binds with, and thereby reduces the absorption of, phosphate. This makes it helpful in treating high blood phosphate (hyperphosphataemia), which occurs in some people with impaired kidney function. However, prolonged heavy use can lead to phosphate deficiency and a consequent weakening of the bones.


Follow instructions on the label. Call your doctor if symptoms worsen.

How taken/used Capsules, chewable tablets, liquid (suspension). The tablets should be well chewed.

Frequency and timing of doses As antacid 4 x daily as needed, or 1 hour before and after meals. Peptic ulcer 4 x daily. Hyperphosphataemia 3–4 x daily with meals.

Dosage range Adults Up to 70ml daily (liquid), 2–10g daily (tablets or capsules). Children over 6 years Reduced dose according to age and weight.

Onset of effect Within 15 minutes.

Duration of action 2–4 hours.

Diet advice For hyperphosphataemia, a low-phosphate diet may be advised in addition to aluminium hydroxide treatment.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Do not take the missed dose. Take your next dose as usual.

Stopping the drug Can be safely stopped as soon as you no longer need it (indigestion). When taken as ulcer treatment or for hyperphosphataemia resulting from kidney failure, do not stop without consulting your doctor.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


Constipation is common with aluminium hydroxide; nausea and vomiting may occur because of the granular, powdery nature of the drug. Bone pain may also occur, but usually only when large doses have been taken regularly for months or years. Vomiting or severe constipation or nausea should be reported to your doctor.


General note Aluminium hydroxide may interfere with the absorption or excretion of many drugs, including oral anticoagulants, digoxin, many antibiotics, penicillamine, corticosteroids, antipsychotics, and phenytoin. It should only be taken at least 2 hours before or after other drugs.

Enteric-coated tablets Aluminium hydroxide may lead to the break-up of the enteric coating of tablets (e.g. bisacodyl, or enteric-coated prednisolone) before they leave the stomach, leading to stomach irritation.


Be sure to consult your doctor or pharmacist before taking this drug if:

· You have a long-term kidney problem.

· You have heart problems.

· You have high blood pressure.

· You suffer from constipation.

· You have a bone disease.

· You have porphyria.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding No evidence of risk.

Infants and children Not recommended under 6 years except on the advice of a doctor.

Over 60 No special problems.

Driving and hazardous work No known problems.

Alcohol No known problems.


Aluminium hydroxide should not be used for longer than 4 weeks without consulting your doctor. Prolonged use of high doses in people with normal kidney function may deplete blood phosphate and calcium levels, leading to weakening of the bones and fractures. In people with kidney disease, long-term treatment may lead to accumulation of aluminium in the brain, causing dementia.