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Aluminium hydroxide

Clinical author's note Michael Stewart 24/5/2021: Alu-Cap® capsules were discontinued in the UK in May 2019. At the time of review there are no branded or generic products solely containing aluminium hydroxide in the UK. Aluminium hydroxide may be available as a special order and is included as an ingredient in some antacid remedies. It may also still be available in other countries. This medicine leaflet is based on medical information accessed in the UK at the time of writing and is left here for reference purposes. Please also refer to the manufacturer's information supplied with your medicine.

Aluminium hydroxide is taken for indigestion. It is also taken to control high phosphate levels in people with kidney disease.

Do not take the capsules at the same time as other medicines - leave two hours between taking aluminium hydroxide capsules and any other medicines.

The most common side-effect is constipation.

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About aluminium hydroxide

Type of medicine

An antacid

Used for

As an antacid for indigestion; to control high phosphate levels in people with kidney disease

Also called

Alu-Cap® (discontinued)

Available as


Aluminium hydroxide is an antacid, which means that it neutralises excess stomach acid associated with indigestion. It also helps to protect the lining of your stomach from acid irritation.

Aluminium hydroxide can also reduce the amount of phosphate which your body absorbs from the food you eat. It combines with phosphate in your stomach, and this is then removed instead of being absorbed. Although aluminium hydroxide is sometimes prescribed for this purpose in people with certain kidney diseases, other medicines are usually used in preference to it.

Before taking aluminium hydroxide

To make sure this is the right treatment for you, before you take aluminium hydroxide capsules it is important that your doctor or pharmacist knows:

  • If you are pregnant or breastfeeding.

  • If you have any problems with the way your liver works or any problems with the way your kidneys work.

  • If you have been told you have low levels of phosphate in your blood.

  • If you have ever had an allergic reaction to a medicine.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

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How to take aluminium hydroxide

  • Before you start taking aluminium hydroxide, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about aluminium hydroxide and will provide you with a full list of the side-effects which you may experience from taking it.

  • For indigestion in adults, take one capsule four times a day with meals and one at bedtime. The capsules are not suitable for children to take as an antacid. Antacids are best taken when symptoms are likely to occur.

  • If you are taking aluminium hydroxide to reduce the amount of phosphate in your body, your doctor will tell you how many capsules to take each day. You could be asked to take between 4-20 capsules a day. Take the capsules spaced out throughout the day with your meals.

  • Aluminium hydroxide can interfere with other medicines taken at the same time and can prevent them form being absorbed properly. It is best if you leave two hours between taking aluminium hydroxide and any other medicines.

Getting the most from your treatment

If you are taking aluminium hydroxide for indigestion

  • There are some foods that may make your symptoms worse. Foods and drinks that have been suspected of this include peppermint, tomatoes, chocolate, spicy foods, hot drinks, coffee and alcoholic drinks. If it seems that a food is aggravating your symptoms, try avoiding it for a while to see if your symptoms improve. Also, try avoiding eating large meals, as these can make your symptoms worse too.

  • If at any time you develop any of the following symptoms, speak with your doctor as soon as possible: difficulty swallowing, loss of blood, weight loss or if you are being sick. These are symptoms sometimes associated with indigestion that your doctor will want to investigate further.

If you have been prescribed aluminium hydroxide for the management of kidney disease

  • Try to keep your regular appointment with your doctor so that your progress can be monitored. Your doctor is likely to want you to have blood tests from time to time.

Continue reading below

Can aluminium hydroxide cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains the most common one associated with aluminium hydroxide. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common aluminium hydroxide side-effects

What can I do if I experience this?


Eat plenty of fibre such as fruit, vegetables and bran and drink plenty of water each day. If you are taking the capsules as an antacid, speak with your pharmacist for advice on a more suitable preparation

If you experience any other symptoms which you think may be due to the capsules, speak with your doctor or pharmacist for further advice.

How to store aluminium hydroxide

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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