Which magnesium is best for migraines? Choosing the right magnesium supplement for migraine prevention can be confusing, given the variety of forms available. Magnesium citrate, magnesium glycinate, and magnesium oxide are the most commonly recommended types, each offering distinct benefits in terms of absorption, tolerability, and clinical evidence. Whilst UK guidelines do not endorse magnesium as first-line prophylaxis, some clinicians consider it as an adjunct treatment for reducing migraine frequency. Understanding the differences between magnesium forms, appropriate dosing, and potential side effects can help you make an informed decision in consultation with your GP or headache specialist.

Understanding Magnesium's Role in Migraine Prevention

Magnesium is an essential mineral involved in over 300 biochemical reactions in the body, including several mechanisms relevant to migraine pathophysiology. Some studies suggest lower magnesium levels in people with migraine, though evidence is mixed and testing is not routinely recommended in UK clinical practice.

The mineral plays several potential roles in migraine prevention. Magnesium regulates neurotransmitter release and modulates the activity of N-methyl-D-aspartate (NMDA) receptors, which are involved in pain transmission. It also influences vascular tone , potentially helping to prevent the abnormal constriction and dilation of blood vessels associated with migraine attacks. Additionally, magnesium acts as a natural calcium channel blocker, which may reduce cortical spreading depression—the wave of electrical activity across the brain thought to trigger migraine aura.

Clinical guidelines have evaluated magnesium supplementation for migraine prevention. While NICE does not endorse magnesium as first-line prophylaxis, some clinicians may consider it as an adjunct treatment. The European Academy of Neurology provides a low to moderate quality recommendation for magnesium in migraine prevention based on the available evidence. Several randomised controlled trials have demonstrated that magnesium supplementation may reduce migraine frequency and severity in some individuals.

It is important to note that oral magnesium supplementation works best as a preventative measure rather than an acute treatment. Benefits typically emerge after several weeks of consistent use, and the response varies considerably between individuals. Intravenous magnesium is not routine migraine care in the UK. Those considering magnesium for migraine management should discuss this with their GP or headache specialist, particularly if they have other medical conditions or take regular medications.

Types of Magnesium Supplements: Key Differences

Not all magnesium supplements are created equal. The mineral must be bound to another substance (a chelate or salt) to form a stable compound, and these different forms vary in their bioavailability—the proportion that is actually absorbed and utilised by the body.

Magnesium oxide is one of the most common and inexpensive forms found in supplements. It contains a high percentage of elemental magnesium by weight (approximately 60%), but generally has lower bioavailability compared to organic forms. This form is more commonly associated with gastrointestinal side effects, particularly loose stools, though this laxative effect is sometimes used therapeutically for constipation.

Magnesium citrate combines magnesium with citric acid and offers moderate to good bioavailability. It is generally well-absorbed and well-tolerated, though it can still have mild laxative effects at higher doses. This form dissolves easily in liquid and is often used in clinical studies.

Magnesium glycinate (or bisglycinate) binds magnesium to the amino acid glycine. This chelated form is often well-tolerated by the digestive system, making it suitable for those prone to gastrointestinal sensitivity. The glycine component may also have calming properties that some find beneficial.

Magnesium threonate is a newer form that has gained attention for its theoretical ability to cross the blood-brain barrier more effectively than other forms. However, research specific to migraine prevention remains limited, and clinical evidence for superior efficacy is lacking.

Other forms include magnesium malate (combined with malic acid), magnesium taurate (bound to the amino acid taurine), and magnesium chloride. Each has distinct characteristics, though it's important to note that all oral magnesium salts can interact with certain medicines such as tetracyclines, quinolones, bisphosphonates, levothyroxine and some antivirals if taken together.

Which Magnesium Is Best for Migraines?

Based on current clinical evidence and practical considerations, magnesium citrate, magnesium glycinate, and magnesium oxide are the forms most commonly used for migraine prevention, each with specific characteristics to consider.

Magnesium oxide has been used in several clinical trials investigating migraine prophylaxis, including studies that demonstrated reduced migraine frequency. Despite its lower bioavailability, the high elemental magnesium content means that standard doses still deliver substantial amounts of the mineral. A typical dose of 400mg of magnesium oxide provides approximately 240mg of elemental magnesium. However, gastrointestinal side effects may limit tolerability for some individuals.

Magnesium citrate represents a good middle ground, offering reasonable bioavailability with generally good tolerability. It has been used successfully in migraine research and is widely available in the UK. This form is particularly suitable for individuals who need reliable absorption but can tolerate mild laxative effects.

Magnesium glycinate is often recommended for migraine sufferers with sensitive digestive systems. Its generally good tolerability may improve long-term adherence—a crucial factor in preventative treatment.

There is no established evidence that magnesium threonate provides superior migraine prevention compared to other forms, despite its theoretical advantages. The limited specific research and higher cost make it a less practical first-line choice.

Ultimately, no UK guidelines endorse a specific 'best' form of magnesium for migraine prevention. The choice should reflect digestive tolerance, budget, and individual response to treatment. Many clinicians suggest starting with magnesium citrate or glycinate and adjusting based on tolerability and effectiveness over 8-12 weeks. It is advisable to consult with a GP or pharmacist before beginning supplementation, particularly for those with kidney disease or taking medications that may interact with magnesium.

Recommended Dosage and How to Take Magnesium for Migraines

The recommended dosage of magnesium for migraine prevention typically ranges from 200-400mg of elemental magnesium daily, based on evidence from clinical trials. It is crucial to distinguish between the total weight of the magnesium compound and the amount of elemental (actual) magnesium it contains, as this varies by formulation. Do not exceed 400mg of elemental magnesium daily from supplements without medical advice, in line with NHS guidance.

For magnesium oxide, a common regimen might be 400mg (providing approximately 240mg of elemental magnesium) taken once or twice daily. For magnesium citrate or glycinate, doses providing 200-400mg of elemental magnesium are typical, which may require taking multiple capsules or tablets depending on the product strength. Always check the supplement label for elemental magnesium content rather than the total compound weight.

Timing and administration can influence both efficacy and tolerability:

• Divide doses: Taking magnesium in two divided doses (morning and evening) may improve absorption and reduce gastrointestinal side effects

• Take with food: Consuming magnesium with meals can enhance tolerability

• Evening dosing: Some individuals prefer taking magnesium in the evening, as it may have mild relaxing properties that support sleep

• Consistency: Maintain regular daily supplementation, as preventative effects develop gradually over weeks

• Medication spacing: If taking medications that interact with magnesium (such as tetracyclines, quinolones, bisphosphonates, or levothyroxine), separate dosing by at least 2-4 hours as advised by your pharmacist

Duration of treatment is important to consider. Migraine prevention with magnesium typically requires at least 8-12 weeks of consistent use before benefits become apparent. NICE guidance on migraine prophylaxis recommends trialling preventative treatments for at least 2-3 months before assessing effectiveness.

Patients should maintain a headache diary during this period, recording migraine frequency, severity, and duration to objectively evaluate response. If no improvement is observed after 3 months of adequate dosing, magnesium may not be effective for that individual, and alternative preventative strategies should be discussed with a healthcare provider.

Magnesium supplementation should be part of a comprehensive migraine management approach that may include identifying and avoiding triggers, maintaining regular sleep patterns, managing stress, and staying well-hydrated.

Potential Side Effects and Safety Considerations

Magnesium supplementation is generally well-tolerated when taken at recommended doses, but certain side effects and safety considerations warrant attention. The most common adverse effect is gastrointestinal disturbance, particularly loose stools or diarrhoea, which occurs because unabsorbed magnesium draws water into the intestines. This effect is dose-dependent and more common with magnesium oxide and citrate than with glycinate.

To minimise digestive side effects:

• Start with a lower dose and gradually increase over 1-2 weeks

• Divide the daily dose into smaller amounts taken throughout the day

• Take magnesium with food

• Consider switching to a more digestively tolerable form if needed

• Reduce the dose if symptoms persist

• Keep supplemental magnesium ≤400 mg/day (NHS guidance) unless under medical supervision; diarrhoea risk increases above this level

Other potential side effects, though less common, include nausea, abdominal cramping, and in rare cases, more serious symptoms of magnesium toxicity (hypermagnesaemia). Symptoms of excessive magnesium include muscle weakness, confusion, irregular heartbeat, and difficulty breathing. However, toxicity is uncommon in individuals with normal kidney function, as healthy kidneys efficiently excrete excess magnesium.

Important safety considerations and contraindications:

• Kidney disease: Individuals with impaired renal function should not take magnesium supplements without medical supervision, as reduced excretion can lead to dangerous accumulation

• Medication interactions: Magnesium can interact with certain medications:

• Separate from tetracyclines/quinolones by at least 2-3 hours
• Separate from levothyroxine and bisphosphonates by at least 4 hours
• May interact with some antivirals (integrase inhibitors); follow specific guidance

• May reduce iron absorption; take at different times

• Heart conditions: Those with heart block or myasthenia gravis should consult their doctor before supplementation

• Pregnancy and breastfeeding: Whilst magnesium is generally considered safe, pregnant or breastfeeding women should discuss supplementation with their midwife or GP

When to seek medical advice:

Contact your GP if you experience persistent diarrhoea, signs of dehydration, or unusual muscle weakness. Seek urgent medical attention for any of these headache red flags: sudden severe 'thunderclap' headache; new neurological deficit; fever/neck stiffness/rash; head injury; new headache in pregnancy/postpartum; new onset after age 50; progressive/worsening pattern; or temporal/scalp tenderness with jaw pain.

If you are taking regular medications or have existing health conditions, consult a healthcare professional before starting magnesium supplementation. Purchase supplements from established UK retailers and check labels for elemental magnesium content. Report any suspected adverse effects to the MHRA Yellow Card scheme.

Frequently Asked Questions