Magnesium L-Threonate and medications.
Magnesium L-Threonate is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
Magnesium L-threonate is a magnesium form designed to raise magnesium specifically in the brain, using a threonate transporter that gives it better brain penetration than common forms like glycinate. That difference is the whole point: it is aimed at memory, synaptic density and cognitive ageing rather than general magnesium repletion. The evidence is Grade B, anchored by Slutsky's animal work on synaptic plasticity and a cognitive review by Zhang, so the case is promising rather than settled. The usual dose is 1,500 to 2,000mg of Magtein, which delivers only about 144mg of elemental magnesium, so it is not a substitute for a standard magnesium supplement. It is a distinct compound from magnesium glycinate and not interchangeable for cognitive goals; the two can be used together since they work differently. It is expensive, which is worth weighing against the modest evidence. Some people get a headache when starting.
Below are the 14 documented pairs we have explicitly assessed for Magnesium L-Threonate: 14 amber. The pairs cluster around 3 mechanisms: Absorption interference, Mineral chelation (absorption), and Renal magnesium wasting (drug-induced). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Absorption interference
Long-term esomeprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term esomeprazole, ask your GP for a magnesium blood test.
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Long-term omeprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term omeprazole, ask your GP for a magnesium blood test.
Long-term pantoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term pantoprazole, ask your GP for a magnesium blood test.
Mineral chelation (absorption)
Magnesium binds to alendronic acid in the gut and blocks absorption, the same way calcium does. Magnesium L-threonate is still elemental magnesium, so it has the same effect. Take alendronic acid first thing on an empty stomach with plain water, stay upright for 30 minutes, then wait at least two hours before any magnesium supplement.
Magnesium can bind to ciprofloxacin in the gut and sharply reduce how much antibiotic you absorb, which may let an infection persist. Take ciprofloxacin at least two hours before, or six hours after, any magnesium supplement.
There are two things to know here, and on balance magnesium is more helpful than harmful. Taking magnesium at the same time as digoxin can slightly reduce how much digoxin you absorb, so it is sensible to separate them by about two hours. At the same time, a low magnesium level makes digoxin more likely to cause dangerous heart rhythms, so keeping your magnesium in the normal range is protective. Magnesium L-threonate is still elemental magnesium, so both points apply. Because digoxin has a narrow safe range, tell whoever prescribes it that you take magnesium.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Magnesium can bind to doxycycline in the gut and reduce how much antibiotic you absorb, which may let an infection persist. Take doxycycline at least two hours before, or six hours after, any magnesium supplement.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Taking magnesium at the same time as gabapentin can lower how much gabapentin your body absorbs, which may make it work less well. Magnesium L-threonate is still elemental magnesium, so the same effect applies. Take gabapentin at least two hours apart from any magnesium supplement, and keep the timing consistent day to day.
Magnesium can bind levothyroxine in the gut and reduce how much you absorb, the same way calcium and iron do. Magnesium L-threonate is still elemental magnesium, so it carries the same binding effect. Take levothyroxine first thing on an empty stomach and take any magnesium supplement at least four hours later, or at bedtime.
Magnesium can bind to minocycline in the gut and reduce how much antibiotic you absorb. The effect is smaller than with older tetracyclines, but keep them apart: take minocycline at least 2 hours before or 6 hours after your magnesium.
Magnesium binds to risedronate in the gut and blocks absorption. Magnesium L-threonate is still elemental magnesium, so it has the same effect. Take risedronate first thing on an empty stomach with plain water, stay upright for 30 minutes, then wait at least two hours before any magnesium supplement.
Renal magnesium wasting (drug-induced)
Bumetanide makes the kidneys pass out more magnesium in the urine, so people on it long term often run low on magnesium. This works the opposite way to most interactions: the medicine lowers your magnesium rather than the supplement affecting the medicine, so taking magnesium is generally a supportive response rather than a hazard. If you take bumetanide long term, especially for heart failure, it is worth asking your GP for a magnesium blood test and letting them know you supplement, since low magnesium can affect heart rhythm.
Furosemide makes the kidneys pass out more magnesium in the urine, so people on it long term often run low on magnesium. This works the opposite way to most interactions: the medicine lowers your magnesium rather than the supplement affecting the medicine, so taking magnesium is generally a supportive response rather than a hazard. If you take furosemide long term, especially for heart failure, it is worth asking your GP for a magnesium blood test and letting them know you supplement, since low magnesium can affect heart rhythm.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
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- the evidence-backed compounds worth adding, and the ones worth dropping
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