Magnesium is generally safe for many people, but it can interact with some medicines. The claim that magnesium “destroys” or “reduces the power” of all blood pressure or heart medicines is exaggerated. The main issue is that magnesium can change how some drugs are absorbed or can add to certain effects.
Medicines to be careful with when taking magnesium
- Certain blood pressure medicines
- Magnesium may add to the blood-pressure-lowering effect of some medications, which could increase dizziness or lightheadedness in some people.
- Examples include calcium channel blockers (such as amlodipine) and some other antihypertensives.
- Diuretics (“water pills”)
- Some diuretics change magnesium levels in the body.
- Examples include furosemide and hydrochlorothiazide. Your healthcare professional may monitor electrolytes if needed.
- Heart rhythm medicines
- Magnesium can affect heart electrical activity, especially in people with kidney problems or abnormal magnesium levels.
- Anyone taking anti-arrhythmia medicines should check before using magnesium supplements.
- Blood thinners
- Magnesium does not usually directly “cancel” blood thinners, but supplement combinations should be reviewed because some products marketed with magnesium contain additional ingredients that may affect bleeding.
Medicines that magnesium commonly interferes with
Magnesium can reduce absorption of several medications if taken at the same time, including:
- Some antibiotics (such as tetracyclines and quinolones)
- Levothyroxine (thyroid medicine)
- Some osteoporosis medicines (bisphosphonates)
A common approach is to separate magnesium supplements from these medicines by a few hours (ask a pharmacist for the best timing for your specific medication)
