magnesium hydroxide at a glance
Medicine class
Antacid and osmotic laxative
Licensed uses
Relief of heartburn, indigestion, dyspepsia, wind and occasional constipation
Form
An oral suspension that should be shaken before measuring
Children
The selected product is not suitable for children under 12 years
What is magnesium hydroxide used for?
The selected product is licensed for short-term symptom relief.
Relief of flatulence, heartburn, dyspepsia and indigestion
Laxative relief of occasional constipation
How does magnesium hydroxide work?
In the stomach, magnesium hydroxide neutralises acid. In the bowel, poorly absorbed magnesium salts retain water in the intestinal contents, helping to soften stools and promote bowel movement.
How to take magnesium hydroxide
Take the suspension by mouth, following its label or leaflet. Shake the bottle thoroughly before measuring and mix it with water as directed. Antacids are generally taken with or soon after food, but instructions for the specific product take priority.
Use an appropriate medicine measure rather than a household spoon.
Keep other medicines separate because magnesium hydroxide can reduce their absorption.
Discard unused selected-product suspension three months after opening.
magnesium hydroxide side effects
Common or expected effects
- Loose stools or diarrhoea
- Abdominal pain, cramping or colic
- Wind, nausea or vomiting may occur with antacids
Get urgent medical advice
- Excess magnesium in the blood, particularly after prolonged or excessive use in kidney impairment
- Flushing, intense thirst, breathing depression, abnormal heart rhythm, collapse or unresponsiveness after excessive use
magnesium hydroxide in pregnancy
The selected product's SmPC advises avoiding use during pregnancy unless recommended by a doctor. UK pregnancy information indicates that laxatives can be used when needed after advice from a pharmacist, midwife or doctor; pregnant people seeking an antacid should also ask which product is suitable.
magnesium hydroxide while breastfeeding
UK specialist guidance states that magnesium hydroxide can be used while breastfeeding a full-term, healthy infant, with no specific infant monitoring usually required. The selected product's SmPC is more cautious and advises use only when recommended by a doctor.
magnesium hydroxide interactions
Magnesium hydroxide can bind medicines in the gut or alter their absorption. A pharmacist should advise how to separate medicines where necessary.
Tetracycline and quinolone antibiotics; some other antibacterials and antifungals
Magnesium hydroxide may reduce absorption and treatment effectiveness when taken together.
Levothyroxine
Absorption may be reduced, so the medicines should not be taken together without spacing advice.
Iron preparations and bisphosphonates
Magnesium hydroxide may reduce absorption from the gut.
Common questions about magnesium hydroxide
Answers are fully visible for fast scanning and source review.
Is magnesium hydroxide an antacid or a laxative?
It is both. It neutralises stomach acid and can also retain water in the bowel to relieve occasional constipation.
What symptoms can magnesium hydroxide relieve?
The selected product is licensed for heartburn, indigestion, dyspepsia, flatulence and occasional constipation.
Why must magnesium hydroxide suspension be shaken?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.