Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Magnesium Sulfate 50%w/v Solution for Injection
⚠ This medicine appears to have been discontinued
The electronic medicines compendium (emc) no longer publishes a Summary of Product Characteristics for this product, which usually means it is no longer marketed in the UK. The patient leaflet below is kept for reference, but the product may not be available.
If you were prescribed this medicine, other products containing Magnesium sulfate heptahydrate may still be available. Do not stop your treatment — ask your pharmacist or GP what to use instead.
What it is and what it is used for
for Magnesium Sulfate Injection is used to treat low levels of magnesium in the blood where it is not possible for the medicine to be taken by mouth. It may also be used to prevent seizures (fits) caused by a serious complication of pregnancy known as eclampsia. It is used in the treatment of acute hypomagnesaemia.
What you need to know before you take it
Magnesium Sulfate Injection You should not be given Magnesium Sulfate Injection if:
- you are allergic to Magnesium Sulfate, its salts or any of the other ingredients of this medicine listed in section 6.
- you suffer from severe kidney failure. Warnings and Precautions Talk to your doctor, pharmacist or nurse before receiving Magnesium Sulfate if you:
- suffer from any kidney problem.
- suffer from disease of the muscles causing drooping eyelids, double vision, difficulty in speaking and swallowing and sometimes muscle weakness in the arms or legs known as myasthenia gravis. During treatment Your blood calcium levels will be routinely monitored whilst taking Magnesium Sulfate. Other medicines and Magnesium Sulfate Injection Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines, including medicines obtained without a prescription. Medicines which may interact with Magnesium Sulfate Injection include:
- Digitalis glycosides e.g. digoxin (a medicine used to treat heart problems)
- Barbiturates (e.g. amobarbital)
- Opioids ( e.g. morphine)
- Hypnotics ( e.g. nitrazepam)
- Muscle relaxants e.g. tubocurarine
- Calcium channel blockers e.g. nifedipine or nimodipine (medicines used to treat high blood pressure) which could result in calcium ion imbalance causing abnormal muscle function.
- Aminoglycoside antibacterials (such as Streptomycin) Pregnancy, breast-feeding and fertility If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Tell your doctor if you are pregnant or trying to become pregnant. Magnesium Sulfate Injection will only be given to you if your doctor considers the benefit of treatment outweighs the risk to the developing baby. Low blood calcium levels and effects on the bones, such a reduced bone density, have been reported in babies whose mothers were given magnesium sulphate continuously for more than 5-7 days during pregnancy. It is not advisable to administer magnesium sulfate during pregnancy or breast-feeding unless considered essential, and it must be administered under medical supervision. If used in pregnant women the baby's heart rate will be monitored and will not be used within 2 hours of delivery. Driving and using machines There are no known effects of Magnesium Sulfate Injection on driving and using machines. Please speak to your doctor before driving or operating machinery.
How to take it
Your doctor will give Magnesium Sulfate Injection to you into a vein (intravenous) or into the muscle (intramuscular) either by injection or infusion (drip). Your doctor will decide how much Magnesium Sulfate should be given to you. For the treatment of low magnesium levels: You will be given up to 40g by slow intravenous infusion (drip) (in glucose 5%) over a period of up to 5 days. To prevent fits associated with eclampsia: After an initial intravenous dose you will be monitored for 24 hours and then you may be given either an intravenous infusion (drip) or regular intramuscular injections. Intramuscular Maintenance Regimen A loading dose of 4g MgSO4 IV (usually in 20% solution) over 5min (minimum, preferably 10-15 min) is followed immediately by 5g MgSO4 (approx. 20mmol Mg2+) (usually in 50% solution) as a deep IM injection into the upper outer quadrant of each buttock. Maintenance therapy is a further 5g MgSO4 IM every 4h, continued for 24h after the last fit (provided the respiratory rate is >16/min, urine output >25ml/h, and knee jerks are present). Intravenous Maintenance Regimen A loading dose of 4g MgSO4 IV (or in some cases 5g MgSO4 IV, as described above, is followed by an infusion of 1g/h continued for 24h after the last fit.
Continued overleaf
Recurrent Convulsions: In both the IM and IV regimens, if convulsions recur, a further 2-4g MgSO4 (depending on the woman's weight, 2g MgSO4 if less than 70Kg is given IV over 5 min. Renal Failure: Doses must be reduced in renal failure. Caution must be observed to prevent exceeding the renal excretory capacity. The dosage should not exceed 20g in 48 hours (100ml of a 20% solution or 80mmol of magnesium ions). Elderly No special recommendation except in patients with kidney problems. If you are given too much or too little Magnesium Sulfate Injection As this medicine will be given to you whilst you are in hospital, it is unlikely that you will be given too much or too little, however, tell your doctor if you have any concerns.
4.Possible side effects Like all medicines, this medicine can cause side effects, although not everybody gets them. Contact your doctor or nurse immediately if you get any of the following:
- Allergic reactions such as shortness of breath, wheezing or difficulty breathing; swelling of the face, lips, tongue or other parts of the body; rash, itching or hives on the skin.
- High blood sugars causing severe dehydration (Hyperosmolar dehydration).
- Heart attack (shortness of breath, chest pain, feeling faint and/or dizzy)
- coma Other side effects:
- feeling or being sick
- flushing of the skin
- feeling thirsty
- loss/slowed reflexes
- temporarily low blood pressure
- drowsiness
- confusion
- muscle weakness
- slowed breathing
- irregular or slow heartbeat
- Problems with the balance of salts and water in the blood. This may lead to thirst (which may be severe), dry mouth, tiredness, restlessness and muscle weakness. There have been isolated reports of low blood calcium levels in mothers and their new-born babies following prolonged use and high doses of magnesium sulphate during pregnancy.
- low phosphate levels in the blood (Hypophosphataemia)
- double vision
- slurred speech . sweating . dizziness . headache . pain and burning at the site of injection following IV/IM injection . risk of itching and tingling . rapid heartbeat
can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects, you can help provide more information on the safety of this medicine.
Possible side effects
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How to store it
Magnesium Sulfate Injection Keep out of the sight and reach of children. This Magnesium Sulfate Injection should not be used after the expiry date which is printed on the carton and ampoule label after EXP. The doctor or nurse will check that the expiry date on the label has not passed before administering the injection to you. The expiry date refers to the last day of that month. Do not store above 25°C. After opening the ampoule, the solution for injection must be used immediately. The ampoule containing the injection will only be used for you and if any injection is left over the doctor/nurse will dispose of it.
Contents of the pack and other information
What Magnesium Sulfate Injection contains The active substance is Magnesium Sulfate Heptahydrate 2ml contains 1g Magnesium Sulfate Heptahydrate (4mmol Mg2+) 5ml contains 2.5g Magnesium Sulfate Heptahydrate (10mmol Mg2+) 10ml contains 5g Magnesium Sulfate Heptahydrate (20mmol Mg2+) The other ingredients are water for injection, hydrochloric acid and sodium hydroxide. What Magnesium Sulfate Injection looks like and contents of the pack Magnesium Sulfate sterile solution for injection/ concentrate for solution for infusion is a clear, solution supplied in 2ml, 5ml and 10ml glass ampoules. 10 ampoules are packed in each carton. Not all pack sizes may be marketed. Marketing Authorisation Holder Aurum Pharmaceuticals Ltd Bampton Road Harold Hill Romford RM3 8UG United Kingdom Manufacturer Macarthys Laboratories Ltd Bampton Road Harold Hill Romford RM3 8UG United Kingdom Product Licence No: PL 12064/0013 This leaflet was last revised in October 2019
Reporting of side effects If you or your child gets any side effects, talk to your doctor, pharmacist or nurse. This includes any
Frequently asked questions about Magnesium Sulfate 50%w/v Solution for Injection
How do I take Magnesium Sulfate 50%w/v Solution for Injection?
Magnesium Sulfate 50%w/v Solution for Injection comes as injection containing 50%. Always follow the dose your doctor or pharmacist has given you, and read the leaflet that comes with the medicine.
What is the active substance in Magnesium Sulfate 50%w/v Solution for Injection?
The active substance in Magnesium Sulfate 50%w/v Solution for Injection is magnesium sulfate heptahydrate.
Are there equivalent medicines to Magnesium Sulfate 50%w/v Solution for Injection?
Medicines with the same active substance, strength and form include: Magnesium Sulfate 50%w/v Solution for Injection or Infusion. They are interchangeable only if your prescriber or pharmacist says so.
Where does this information come from?
This leaflet reproduces the patient information leaflet approved for Magnesium Sulfate 50%w/v Solution for Injection, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.
Can I get Magnesium Sulfate 50%w/v Solution for Injection without a prescription?
Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.
About this leaflet
The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.
- Source: electronic medicines compendium (emc), Datapharm
- Active substance: magnesium sulfate heptahydrate
- Official document: view the original leaflet on emc →
⚕For healthcare professionals — Summary of Product Characteristics (SmPC)Full SmPC: dosage, interactions, contraindications, warnings+
4.1. Therapeutic indications
• Treatment of Magnesium deficiency in hypomagnesaemia where the oral route of administration may be inappropriate.
• To prevent further seizures associated with eclampsia.
4.2. Posology and method of administration
Dosage should be individualised according to patient's needs and responses.
Plasma levels should also be monitored throughout therapy.
a) Treatment of magnesium deficiency in hypomagnesaemia:
For intravenous administration, a concentration of 20% or less should be used; the rate of injection not exceeding 1.5ml/minute of a 10% solution or its equivalent.
Up to 40g MgSO4 (equivalent to 160mmol Mg2+) by slow intravenous infusion (in glucose 5%) over up to 5 days, may be required to replace the deficit (allowing for urinary losses).
Mild magnesium deficiency
1g intramuscularly every 6 hours for 4 doses.
Severe magnesium deficiency
Up to 250mg/kg intramuscularly given within a period of 4 hours or 5g/litre of infusion solution intravenously over 3 hours
Paediatric population
It is recommended that the solution be diluted to 20% w/v prior to intramuscular injection
Elderly
No special recommendation except in renal impairment, see below
Renal impairment:
Dosage should be reduced in renal impairment. Plasma magnesium concentrations should be monitored throughout therapy
b) To prevent further seizures associated with eclampsia:
An initial intravenous (IV) loading dose is followed for 24h by either an IV infusion, or regular intramuscular (IM) injections.
Intramuscular Maintenance Regimen
A loading dose of 4g MgSO4 (approx. 16mmol Mg2+) IV (usually in 20% solution) over 5min (minimum, preferably 10-15 min) is followed immediately by 5g MgSO4 (approx. 20mmol Mg2+) (usually in 50% solution) as a deep IM injection into the upper outer quadrant of each buttock.
Maintenance therapy is a further 5g MgSO4 (approx. 20mmol Mg2+) IM every 4h, continued for 24h after the last fit (provided the respiratory rate is >16/min, urine output >25ml/h, and knee jerks are present).
Intravenous Maintenance Regimen
A loading dose of 4g MgSO4 (approx. 16mmol Mg2+) IV (or in some cases 5g MgSO4 (approx. 20mmol Mg2+) IV), as described above, is followed by an infusion of 1g/h continued for 24h after the last fit.
Recurrent Convulsions: In both the IM and IV regimens, if convulsions recur, a further 2-4g MgSO4 (approx. 8 - 16mmol Mg2+) (depending on the woman's weight, 2g MgSO4 (approx. 8mmol Mg2+) if less than 70Kg) is given IV over 5 min.
* The Eclampsia Trial Collaborative Group (Duley L et al) (1995) Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial., The Lancet, Vol. 345, pp. 1455-1463.
Appropriate reductions in dosage should be made for patients with renal impairment; a suggested dose reduction in severe renal impairment is a maximum of 20g MgSO4 (approx. 80mmol Mg2+) over 48 hours.
Method of administration
Magnesium sulfate injection may be administered by intramuscular or intravenous routes.
Intramuscular therapy should be used only when peripheral venous access is impossible.
4.3. Contraindications
Hypersensitivity to magnesium and its salts or to any of the excipients listed in section 6.1.
Magnesium sulfate is contraindicated in patients with severely impaired renal function.
4.4. Special warnings and precautions for use
Magnesium sulfate must be used with caution in patients suspected of or known to have renal impairment.
Magnesium sulfate should not be used in hepatic coma if there is a risk of renal failure.
Parenteral magnesium salts should be used with caution in patients with myasthenia gravis.
Serum calcium levels should be routinely monitored in patients receiving magnesium sulfate.
4.5. Interaction with other medicinal products and other forms of interaction
Administer with caution to patients receiving digitalis glycosides. Magnesium sulfate should not be administered concomitantly with high doses of barbiturates,opiods or hypnotics due to the risk of respiratory depression
The action of non-depolarising muscle relaxants such as tubocurarine is potentiated and prolonged by parenteral magnesium salts.
Concomitant use of calcium channel blockers such as nifedipine or nimodipine may rarely lead to a calcium ion imbalance and could result in abnormal muscle function.
The neuromuscular blocking effects of parenteral magnesium and aminoglycoside antibacterials may be additive.
4.6. Fertility, pregnancy and lactation
Pregnancy
Safety in human pregnancy has not been established, however, in the medical emergency of a patient having Eclampsia, Magnesium Sulfate can be administered to relieve this condition, which may be life threatening to both mother and baby.
Magnesium crosses the placenta. When used in pregnant women, foetal heart rate should be monitored and use within 2 hours of delivery should be avoided.
Magnesium sulfate can cause skeletal adverse effects when administered continuously for more than 5 to 7 days to pregnant women. There are retrospective epidemiological studies and case reports documenting fetal adverse effects including hypocalcaemia, skeletal demineralization, osteopenia and other skeletal adverse effects with maternal administration of magnesium sulfate for more than 5 to 7 days. The clinical significance of the observed effects is unknown.
If prolonged or repeated exposure to magnesium sulfate occurs during pregnancy monitoring of neonates for abnormal calcium or magnesium levels and skeletal adverse effects should be considered.
Breast-feeding
As with all drugs it is not advisable to administer magnesium sulfate during pregnancy or breastfeeding unless considered essential, and it must be administered under medical supervision.
Fertility
No studies and/or data are available on the effects on fertility.
4.7. Effects on ability to drive and use machines
No studies on the effects on the ability to drive and use machines have been performed.
4.8. Undesirable effects
Metabolism and nutrition disorders
Electrolyte/fluid abnormalities (hypophosphataemia, hypertonic dehydration)
Hypersensitivity reactions.
Hypocalcaemia.
Pain or burning at the injection site following IV/IM administration.
Hypermagnesaemia characterised by flushing, sweating, thirst, hypotension, drowsiness, dizziness, headache, risk of itching and tingling, nausea, vomiting, confusion, slurred speech, double vision, loss of tendon reflexes due to neuromuscular blockade, muscle weakness, respiratory depression, electrolyte/fluid abnormalities (hypophosphataemia, hyperosmolar dehydration), ECG changes (prolonged PR, QRS and QT intervals), bradycardia, tachycardia cardiac arrhythmias, coma and cardiac arrest.
There have been isolated reports of maternal and fetal hypocalcaemia with high doses of magnesium sulfate (see section 4.6).
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: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
4.9. Overdose
Appropriate action should be taken to reduce the blood level of magnesium to avoid hypermagnesaemia. Neuromuscular blockade associated with hypermagnesaemia may be reversed with calcium salts, such as Calcium Gluconate, which should be administered intravenously in a dose equivalent to 2.5 to 5mmol of calcium.
💬 Ask about this leaflet
Ask anything about Magnesium Sulfate 50%w/v Solution for Injection. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.
Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.
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