Can too much magnesium cause muscle twitching?

The physiology runs the other way, which is the reason excess magnesium does not twitch a muscle

Can too much magnesium cause muscle twitching is answered by a piece of physiology that runs in the opposite direction to the worry. At the neuromuscular junction, where a nerve tells a muscle fibre to contract, calcium entering the nerve terminal triggers the release of acetylcholine, and magnesium antagonises that calcium, reducing acetylcholine release and damping transmission, which is why magnesium in excess, the hypermagnesaemia of failed kidneys or laxative-scale intake, produces muscle weakness, lost reflexes and, at the extreme, weakened breathing, a depression of the junction rather than an excitation of it, and why intravenous magnesium is used clinically to calm certain overexcited states. Magnesium deficiency runs the other way: with less magnesium to oppose calcium, the junction and the nerve membranes become more excitable, and twitching, cramps, tremor and, in severe deficiency, tetany follow, the hypomagnesaemia picture in which twitching is a symptom of too little, not too much. So too much magnesium in the blood does not cause twitching, it causes the opposite, and a healthy adult's kidneys prevent too much in the blood from a capsule habit anyway, the overflow-valves page's picture, so the direct route is closed twice, by the physiology and by the kidneys.

The indirect route, reverse causation, and the question filed

The indirect route is the one that can actually connect a large magnesium dose to a twitch, and it runs through the gut rather than the junction: a surplus dose, over the 400mg guidance level or a laxative salt at any dose exceeding absorption, produces osmotic diarrhoea, and diarrhoea loses potassium, sodium and fluid, low potassium and dehydration being established causes of muscle twitching and cramping, so a reader who has been taking a large citrate or oxide dose, running to the bathroom and noticing a flickering calf has a chain, magnesium to diarrhoea to electrolytes to twitch, with loose stools as its signature and a lower dose in a better-absorbed salt, fluids and potassium-rich food as its fix. Reverse causation is the commonest true story, as on the cramps-from-excess page: benign fasciculations, the flickers in a calf, an eyelid or a thumb that come with fatigue, caffeine, stress, hard training and poor sleep, sent the reader to the internet, the internet sent them to magnesium, the twitches continued because no trial supports magnesium for benign fasciculation in someone with adequate status, the dose rose, and the rising dose added the loose stools and the worry, so that the reader asking whether too much magnesium causes twitching is a reader whose twitching caused the too much. The triage that ends it is the twitching page's: no weakness, no wasting and no spreading means benign, and the levers are the caffeine curfew, sleep, a deload and less anxiety about the twitch itself; weakness, wasting or spreading means a GP. The question filed: too much magnesium does not cause twitching directly, the physiology producing weakness rather than excitation and the kidneys preventing excess anyway, can cause it indirectly through the electrolytes a surplus dose's diarrhoea loses, and most often did not cause it at all, the worked example being a dose under the level with nothing to lose in the gut, bisglycinate at 300mg elemental, £19.99 for 90 days at 22p, taken for the muscle-function sentence by audit and not for a twitch that caffeine explains.

The verdict, a physiology that points the other way

Can too much magnesium cause muscle twitching: not directly, because magnesium antagonises calcium at the neuromuscular junction so that excess depresses transmission and produces weakness while deficiency raises excitability and produces twitching, the direct route being closed by the physiology and by the kidneys that prevent excess from a capsule habit, but indirectly through the potassium and fluid a surplus dose's diarrhoea loses, and most often not at all, the twitch having come from caffeine, stress and fatigue and the dose having risen to chase it. The dose with nothing to lose in the gut: Futuro Labs Magnesium Glycinate, bisglycinate, 300mg elemental at 80% NRV, £19.99 for 90 days at 22p a day.

What to check on the label

Questions people also ask

Does high magnesium cause twitching?

No: at the neuromuscular junction magnesium antagonises calcium and reduces acetylcholine release, so excess magnesium depresses transmission and causes weakness and lost reflexes, while it is deficiency that raises excitability and causes twitching, cramps and tremor.

I started magnesium and my twitching got worse, why?

Two honest possibilities: a surplus or laxative-salt dose caused diarrhoea and the potassium and fluid it lost are twitching the muscle, fixed by a lower dose in a better-absorbed salt with fluids and potassium-rich food; or the twitch was caffeine, stress and fatigue all along and the capsule changed nothing.

Can magnesium diarrhoea cause muscle twitching?

Yes, indirectly: diarrhoea from a surplus dose loses potassium, sodium and fluid, and low potassium and dehydration are established causes of twitching and cramping, with loose stools before the twitch as the signature.

When is muscle twitching a sign of too little magnesium?

In genuine hypomagnesaemia from alcohol, medicines, gut loss or a diet that ran badly light, where twitching, cramps and tremor come with a low serum magnesium on a blood test and repletion settles them over days to weeks.

What actually stops benign muscle twitching?

The caffeine curfew, especially an evening pre-workout, sleep, a deload after stacked hard weeks and less anxiety about the twitch itself, over weeks; twitching with weakness, wasting or spreading goes to a GP.

Sources

1. The magnesium and neuromuscular junction physiology: magnesium antagonises calcium at the presynaptic terminal and reduces acetylcholine release, so magnesium excess depresses neuromuscular transmission and produces weakness, while magnesium deficiency increases neuromuscular excitability and produces twitching, cramps and tetany. PubMed record
2. The hypermagnesaemia literature: raised serum magnesium is rare with normal kidney function and occurs with impaired excretion or massive intake from magnesium laxatives and antacids, presenting with nausea, lethargy, low blood pressure, muscle weakness and slowed heart conduction, and treated in hospital with intravenous calcium and, where needed, dialysis. PubMed record
3. The hypomagnesaemia literature: clinically low serum magnesium presents with cramps, tremor, weakness and, when severe, arrhythmias and seizures, with alcohol misuse, proton-pump inhibitors, diuretics and gastrointestinal loss the common causes, and serum magnesium an imperfect marker of tissue status. PubMed record
4. The benign fasciculation literature: muscle twitching without weakness or wasting is common and associated with fatigue, caffeine, stress, exercise and anxiety, while twitching with progressive weakness or wasting warrants neurological assessment. PubMed record

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