Magnesium citrate

The most common forms are tablets and capsules, which are easy to administer and dose accurately, but magnesium citrate is also available as a powder or liquid, preferred in certain clinical contexts.

A representative example is Solgar Magnesium Citrate, 200 mg, formulated without sugar, salt, starch, yeast, wheat, soya, gluten or lactose, and free from preservatives, artificial flavours or colours.

Formulations with higher concentrations are also available on the market, such as Zenyth magnesium citrate 1200 mg, intended for situations where a higher intake or a controlled laxative effect is required.

Magnesium citrate is recommended for the prevention and correction of magnesium deficiency, which manifests as muscle cramps, persistent fatigue, irritability, sleep disturbances or palpitations. 

It is useful for supporting the normal functioning of the nervous system during periods of intense mental or physical stress, as well as for reducing mild anxiety and states of tension. 

Thanks to its osmotic effect, magnesium citrate is also recommended for occasional constipation, as it has a mild laxative effect. 

For adults, the usual dose of 200 mg magnesium citrate is one tablet per day, preferably taken with meals to reduce the risk of gastric discomfort. 

For capsules, 1–3 capsules a day are recommended, taken with meals and plenty of liquid. To reduce the laxative effect, the dose should be divided into separate doses. 

The administration of magnesium citrate is contraindicated in people with severe renal impairment, as magnesium excretion is compromised, increasing the risk of hypermagnesaemia. 

Furthermore, it is not recommended in cases of chronic diarrhoea, intestinal obstruction or hypersensitivity to any of the product’s ingredients.

Magnesium citrate is characterised by high bioavailability, as it is well absorbed in the gut. 

The product is suitable for vegetarians and vegans, as the capsules are plant-based and do not contain major allergens such as gluten or lactose. In the case of long-term treatment, it is recommended to monitor the total magnesium intake from both diet and supplements.

The most common adverse reactions associated with magnesium citrate are gastrointestinal in nature and include diarrhoea, bloating, flatulence or abdominal cramps, particularly at high doses. 

These effects are generally mild and reversible upon reducing the dose. Serious reactions are rare and generally occur in cases of overdose or renal failure.

Magnesium citrate may interfere with the absorption of certain medicines, such as tetracyclines, fluoroquinolones, bisphosphonates or levothyroxine, which is why it is recommended to take them at least 2–4 hours apart. 

Foods rich in fibre or phytates may reduce magnesium absorption, whilst vitamin B6 may have a synergistic effect, facilitating the cellular utilisation of magnesium.

An overdose of magnesium citrate can cause hypermagnesaemia, which presents with nausea, vomiting, low blood pressure, muscle weakness and, in severe cases, heart rhythm disturbances. 

If any suggestive symptoms appear, use should be discontinued and medical assessment is required.

Magnesium citrate products should be stored in their original, tightly closed packaging in a dry place, protected from light and excessive heat. The optimal storage temperature is below 25 °C and the product must be kept out of the reach of children.

• WebMD, Health benefits of magnesium citrate
• MDPI, Unlocking the Power of Magnesium: A Systematic Review and Meta-analysis of its Role in Oxidative Stress and Inflammation
• SpringerLink, Greater bioavailability of magnesium citrate compared to magnesium oxide, demonstrated by the assessment of urinary excretion and serum levels following a single-dose administration in a randomised crossover study.
• Healthline, How to use magnesium citrate for constipation