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Magnesium Hydroxide Mixture BP

Active Ingredient:
magnesium hydroxide
Thornton & Ross Ltd See contact details
About Medicine
{healthcare_pro_orange} This information is for use by healthcare professionals
Last updated on emc: 18 Sep 2020
1. Name of the medicinal product

Magnesium Hydroxide Mixture

2. Qualitative and quantitative composition

Magnesium Hydroxide Paste Concentrated 1.325g/5ml

Excipient(s) with known effect:

Sodium benzoate 2.5mg/5ml

For a full list of excipients see section 6.1

3. Pharmaceutical form


4. Clinical particulars
4.1 Therapeutic indications

1. For relief of the symptoms of flatulence, heartburn, dyspepsia and indigestion

2. As a laxative for relief of occasional constipation

4.2 Posology and method of administration


Recommended doses and dosage schedule

1. As an antacid

Adults, the elderly and children over 12 years: one to two 5ml spoonfuls in a little water when required. Children under 12 years: not suitable.

2. As a laxative

Adults, the elderly and children over 12 years: 25 - 50ml (five to ten 5ml spoonfuls) in a glass of water at bedtime.

Children under 12 years: not suitable.

Directions for use: Shake the bottle.

4.3 Contraindications

Contraindicated in severe renal failure, acute gastrointestinal conditions and in hypersensitivity to magnesium salts or any of the other ingredients.

4.4 Special warnings and precautions for use

Use with caution in the elderly and debilitated and in patients with impaired liver function. Also in patients with impaired kidney function as hypermagnesaemia may result.

Keep all medicines away from children.

If constipation persists consult your doctor.

Not suitable for children under 12.

Discard any unused mixture 3 months after opening.

Paediatric population

In young children the use of magnesium hydroxide can produce a hypermagnesemia, especially if they present renal impairment or dehydration.

Excipient warnings :

This medicine contains less than 1mmol sodium (23mg) per 5ml dose, that is to say essentially 'sodium-free'.

This medicine contains 2.5mg sodium benzoate in each 5ml dose, which is equivalent to 0.05% w/v.

4.5 Interaction with other medicinal products and other forms of interaction

As a precaution for antacids, in order to minimise the risk of interactions affecting pharmacokinetics of concomitantly administered products, drug administrations should be separated by approximately 2 to 3 hours.

Magnesium salts reduce the absorption of a number of other drugs taken concomitantly. These include ACE inhibitors (captopril, enalapril, and fosinapril), antibacterials and antifungals (azithromycin, cefaclor, cefpodoxime, isoniazid, itraconazole, nitrofurantoin, rifampicin, tetracyclines, ketoconazole and the quinolone group of antibacterials); antivirals (atazanavir, fosamprenavir, tipranavir); antihistamines (fexofenadine); bisphosponates, corticosteroids (deflazacort); digoxin, dipyridamole, diflunisal, antiepileptics (gabapentin and phenytoin), ulcer healing drugs (lansoprazole); levothyroxine, mycophenolate, iron preparations, lipid regulating drugs (rosuvastatin); antipsychotics (sulpiride, phenothiazines), chloroquine, hydrochloroquine, proguanil, and penicillamine. Concomitant use with sodium polystyrene sulphonate may produce metabolic alkalosis. Alkaline urine due to some antacids increases excretion of aspirin. Antacids should be avoided with nilotinib.

Antacids possibly reduce absorption of bile acids.

Urine alkalinisation secondary to administration of magnesium hydroxide may modify excretion of some drugs; thus, increased excretion of salicylates has been seen.

4.6 Fertility, pregnancy and lactation

As with all other medicines, use of this product should be avoided in the above conditions unless recommended by a doctor.

4.7 Effects on ability to drive and use machines

None known

4.8 Undesirable effects

System Organ Class

Very Rare (<1/10,000)

Not known (cannot be estimated from the available data)

Metabolism and nutrition disorders

Hypermagnesmia. Observed after prolonged administration of magnesium hydroxide to patients with renal impairment.

Gastrointestinal disorders

Abdominal pain, Diarrhoea (a dose-dependent effect), Colic.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at or search for 'MHRA Yellow Card' in the Google Play or Apple App Store.

4.9 Overdose

Excessive use of magnesium containing antacids has rarely resulted in hypermagnesaemia, symptoms of which include flushing of the skin, thirst, respiratory depression, cardiac arrhythmias, coma and cardiac arrest.

Treatment should consist of the administration of calcium gluconate injection 10% intravenously at a dose of 10 - 20ml, to counteract respiratory depression or heart block. If renal function is normal, sufficient fluids should be given to aid removal of magnesium from the body. Dialysis may be necessary in patients with impaired renal function or severe hypermagnesaemia.

5. Pharmacological properties
5.1 Pharmacodynamic properties

Magnesium hydroxide is an antacid with slow neutralising action and a mild laxative action.

5.2 Pharmacokinetic properties

Magnesium salts are poorly absorbed following oral administration. Approximately one third of magnesium is absorbed from the small intestine, and excreted mainly in the urine with small amounts in breast milk and saliva.

5.3 Preclinical safety data


6. Pharmaceutical particulars
6.1 List of excipients

Sodium Benzoate (E211)

Purified Water

6.2 Incompatibilities

None known

6.3 Shelf life

12 months unopened, 3 months after first opening.

6.4 Special precautions for storage

Do not freeze

Do not store above 25° C

6.5 Nature and contents of container

500ml: Glass bottle with white plastic child resistant cap with EPE/Saranex liner.

6.6 Special precautions for disposal and other handling


7. Marketing authorisation holder

Thornton & Ross Ltd

Linthwaite Laboratories



8. Marketing authorisation number(s)

PL 00240/6500R

9. Date of first authorisation/renewal of the authorisation

27/09/88 / 24/09/2001

10. Date of revision of the text


Thornton & Ross Ltd
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Linthwaite, Huddersfield, West Yorks, HD7 5QH
Medical Information Direct Line
+44 (0) 1484 848164
Medical Information e-mail
[email protected]
Customer Care direct line
+44(0)1484 848200