What Is Magnesium?

Magnesium is an essential mineral crucial for many bodily functions. It is necessary for more than 300 biochemical reactions in the body, including blood sugar control, blood pressure regulation, and muscle and nerve function. Magnesium also supports bone health and is important for immune health and normal heart rhythm.

Magnesium is naturally found in many foods and is also available as a nutritional supplement. Good dietary sources of magnesium include nuts, seeds, legumes, whole grains, fruits such as bananas and avocados, and dark, leafy greens such as spinach. Magnesium is also added as a nutrient to cereals and other fortified foods.

While magnesium is available as a supplement, it is not recommended unless you are magnesium deficient. There are some medications you shouldn't mix with magnesium to avoid potential side effects or interactions.

1. Antibiotics

Magnesium can interact with certain antibiotics, including tetracyclines such as demeclocycline and doxycycline, and quinolone antibiotics such as ciprofloxacin and levofloxacin.

These antibiotics taken with magnesium—or too soon after magnesium—may not be absorbed properly or work as effectively. To ensure optimal absorption, take antibiotics at least two hours before or 4–6 hours after taking magnesium.

2. Diuretics

Diuretics are drugs that help the body get rid of excess salt and fluid by increasing urination. Depending on the type of diuretic, magnesium loss through urine may increase or decrease.

Some diuretics can cause hypomagnesemia, a condition in which magnesium levels become dangerously low. Symptoms may include muscle weakness, hyperexcitability, and sleepiness.

3. Bisphosphonates

Magnesium-rich supplements can decrease the absorption of oral bisphosphonates, drugs used to treat osteoporosis. This interaction can occur when medications like alendronate (Fosamax) are taken too soon before or after magnesium.

To avoid this, take bisphosphonates at least two hours before or after magnesium supplementation.

4. Proton Pump Inhibitors (PPIs)

Prolonged use of PPIs (over one year) can cause low blood magnesium levels. PPIs are used to treat peptic ulcers and acid reflux. Examples include esomeprazole (Nexium) and lansoprazole (Prevacid).

If you use PPIs regularly, ask your healthcare provider to check your magnesium levels periodically.

5. Zinc

Zinc is a trace mineral important for immune function and wound healing. However, taking very high doses of zinc alongside magnesium can hinder magnesium absorption.

To avoid this interaction, take zinc and magnesium supplements at different times of the day.

When To See a Healthcare Provider

If you take any of the above medications, speak with your healthcare provider before adding magnesium supplements. In some cases, magnesium can still be taken at a different time than your medication.

Also contact your provider if you experience side effects from magnesium such as:

  • Skin flushing

  • Abdominal pain

  • Diarrhea

  • Nausea or vomiting

  • Electrolyte imbalances (e.g., hypocalcemia, hyperkalemia)

  • Muscle weakness or abnormal heartbeat

In rare cases, high magnesium intake can cause breathing difficulty, heart failure, or hypothermia. If you experience serious side effects, seek emergency care immediately.

A Quick Review

Magnesium supports over 300 bodily functions and is found in many foods. While magnesium supplements can be beneficial for those with deficiencies, certain medications should not be taken with magnesium, including antibiotics, PPIs, diuretics, bisphosphonates, and high doses of zinc.

Always consult a healthcare provider before combining magnesium supplements with other medications.