The headline “NEVER Use Magnesium If You Are Taking Any of the Following Medications” is an exaggeration. Magnesium supplements do not need to be avoided by everyone, but they can interact with certain medications or require caution.
Here are the main medications to be aware of:
1. Certain antibiotics
Magnesium can reduce the absorption of:
- Tetracyclines (such as doxycycline)
- Fluoroquinolones (such as ciprofloxacin and levofloxacin)
What to do: Take magnesium 2–6 hours apart (the exact interval depends on the antibiotic).
2. Levothyroxine (thyroid hormone)
Magnesium can reduce how much levothyroxine your body absorbs.
What to do: Take magnesium at least 4 hours after levothyroxine.
3. Bisphosphonates (for osteoporosis)
Examples:
- Alendronate
- Risedronate
Magnesium can interfere with their absorption.
What to do: Take magnesium several hours later, following the medicine’s instructions.
4. Some blood pressure medications
Magnesium can have a mild blood pressure–lowering effect. When combined with blood pressure medicines, it may increase the risk of low blood pressure in some people, although this is usually not a problem at recommended doses.
5. Diuretics (“water pills”)
Some diuretics:
- Increase magnesium loss (such as furosemide and hydrochlorothiazide).
- Others reduce magnesium excretion (such as amiloride and spironolactone).
Whether you need magnesium depends on the specific medicine and your blood magnesium level.
6. Digoxin
People taking digoxin should consult their healthcare professional before taking magnesium supplements, as abnormal magnesium levels can affect heart rhythm.
7. People with significant kidney disease
This isn’t a medication interaction, but it’s one of the most important cautions. Reduced kidney function can make it difficult to remove excess magnesium, increasing the risk of dangerously high magnesium levels.
Common side effects
At typical doses, magnesium supplements most often cause:
- Diarrhoea
- Stomach cramps
