The headline “Magnesium might clash badly with blood-pressure or heart medicines and reduce their power” is too broad. Magnesium supplements can interact with some medicines, but they do not generally make common blood-pressure medicines ineffective. The important interactions depend on the particular drug. Office of Dietary Supplements+1
Medicines to be particularly careful about
- Diuretics (“water pills”) such as furosemide, bumetanide and hydrochlorothiazide can change magnesium levels. Some increase magnesium loss through urine, while potassium-sparing diuretics such as spironolactone can reduce magnesium loss. Office of Dietary Supplements
- Digoxin is particularly important in people taking heart medication. Magnesium-containing antacids/laxatives and other supplements can affect medication absorption, and electrolyte abnormalities can increase the risks associated with digoxin. Don’t change digoxin or magnesium without medical advice. nhs.uk+1
- Certain antibiotics—especially doxycycline, ciprofloxacin and levofloxacin—can be poorly absorbed if taken together with magnesium. They generally need to be separated from magnesium supplements by several hours. Office of Dietary Supplements
- Alendronate and other oral bisphosphonates: magnesium can reduce their absorption; they should be separated by at least 2 hours. Office of Dietary Supplements
What about common BP medicines?
For medicines such as amlodipine, lisinopril, losartan, metoprolol and similar drugs, magnesium isn’t generally known for simply “cancelling out” their blood-pressure-lowering effect. However, magnesium itself can lower blood pressure slightly, so combining supplements with several BP medicines could potentially contribute to low blood pressure or dizziness in some people. Office of Dietary Supplements
At 83, I’d be particularly cautious about starting a magnesium supplement without checking your medication list and kidney function. The kidneys normally remove excess magnesium, and very high supplemental doses can cause serious problems, including abnormal heart rhythms. Office of Dietary Supplements
If you give me the names and doses of your blood-pressure/heart medicines and the magnesium product (including mg per tablet), I can check them one by one and tell you which combinations deserve attention.
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