10 Medications You Should Not Take With Magnesium

Bisphosphonates are a class of drugs widely used to treat osteoporosis and other bone diseases. These medications work by inhibiting bone resorption—the breakdown of old damaged bone tissue and its absorption into the body. This results in reduced risk of bone fractures in people with osteoporosis. The most common bisphosphonates include (3):

• Alendronate (Fosamax)
• Risedronate (Actonel)
• Ibandronate (Boniva)
• Pamidronate (Aredia)
• Zoledronate (eclast, Zomet)

Magnesium can interfere with the absorption of bisphosphonates that are taken orally. This can cause decreased absorption of the drug, undermining the effectiveness of the medical treatment.

Supplements or medications that contain magnesium should be taken at least two hours apart from oral bisphosphonates (4).

Magnesium can reduce the absorption of certain antibiotics by bonding to them to form insoluble, nonabsorbable compounds. These antibiotics include:

• Quinolones (e.g., Cipro, Levaquin)
• Tetracyclines (e.g., Declomycon, Vibramycin)

To avoid this interaction, it is recommended to take these antibiotics 2 hours before or 4-6 hours after taking a magnesium supplement (4, 5).

Diuretics are medications that increase the flow of urine by promoting the excretion of water and electrolytes (e.g., sodium) by the kidneys. Thus, they prevent the buildup of excess fluid in body tissues. Diuretics are most often used to treat edema, high blood pressure, and heart failure (6).

With regard to potential interactions between diuretics and magnesium, the drug can disrupt the functioning of magnesium in the body, rather than the reverse. Specifically, two classes of diuretics—loop diuretics (e.g., Lasix) and thiazide diuretics (e.g., HCTZ)—can deplete magnesium in the body by inducing the loss of magnesium in the urine.

Signs of low magnesium levels include (4, 7):

• Fatigue
• Poor appetite
• Muscle cramps
• Abnormal heart rhythms

On the flip side, another class of diuretics—potassium-sparing diuretics (e.g., Aldactone)—acts to ‘spare’ magnesium by reducing magnesium excretion via the urine (4).

Proton pump inhibitors (PPIs) are medications that reduce the production of acid in the stomach. Reducing stomach acid promotes healing of disorders such as gastroesophageal reflux disease (GERD), stomach and intestinal ulcers, and Helicobacter pylori infections. Common PPIs include:

• Omeprazole (Prilosec)
• Pantoprazole (Protonix)
• Esomeprazole (Nexium)

Native Note: PPIs are among the most widely prescribed drugs worldwide (8).

Accumulating evidence indicates that long-term use of PPIs can cause low blood levels of magnesium as a side effect. Magnesium needs stomach acid for optimal absorption. PPIs may reduce the absorption of magnesium through its acid-lowering effects.

In fact, low blood magnesium has been reported in 13% of people on PPIs (9).

Clinical monitoring for magnesium deficiency is recommended for people taking PPIs long-term. This is particularly important for those with diabetes or cardiovascular disease since low magnesium raises their risk of disease-associated complications (9).

Although not as potent as medications, magnesium supplements can significantly lower blood pressure at doses ≥ 400 mg/day for 12 weeks or longer. One mechanism for this benefit involves the role of magnesium as a natural “calcium channel blocker.” (10). As such, magnesium blocks calcium from entering cells, causing muscle cells in the blood vessel walls to relax and dilate (rather than contract from the action of calcium), potentially lowering blood pressure (11).

So can you take magnesium with blood pressure medication?

As would be expected, magnesium may have additive effects on lowering blood pressure when taken along with all high blood pressure medications. Magnesium supplementation may be used as a strategy to achieve blood pressure goals without increasing medications (12, 13).

However, since blood pressure could potentially drop too low, medical supervision is imperative. People who take blood pressure medications are advised to consult their healthcare provider should they wish to take magnesium supplements.

Gabapentin (Neurontin) is a medication commonly used to treat seizures and a variety of pain conditions caused by nerve damage. These conditions include diabetic neuropathy as well as nerve pain caused by shingles. Gabapentin is among the top 10 most commonly prescribed medications in the U.S. (14).

Magnesium decreases the intestinal absorption of gabapentin when they are taken at the same time (15). Therefore, gabapentin should be taken at least 2 hours prior to taking any supplement or antacid containing magnesium (16).

As a safe and effective medication, metformin is frequently prescribed as a first-choice therapy for the treatment of type 2 diabetes. However, metformin can significantly reduce blood levels of magnesium. Low levels of magnesium worsen insulin resistance—a hallmark of type 2 diabetes. Conversely, magnesium supplementation can help reverse insulin resistance and reduce the risk of developing complications of diabetes such as cardiovascular diseases and chronic kidney disease (17, 18)

Sulfonylureas are another type of diabetes medication that can interact with magnesium. For example, magnesium has been shown to speed the absorption of glipizide (Glucotrol), a common sulfonylurea drug (19).

Given these potential interactions and the greater occurrence of magnesium deficiency in diabetes, routine monitoring of magnesium status in people with type 2 diabetes may be particularly beneficial (18).

Levothyroxine (Synthroid, Levoxyl) is the primary medication used to treat hypothyroidism (low thyroid). Adequate stomach acid is necessary for adequate absorption of levothyroxine. However, antacids containing magnesium can cause a reduction in stomach acid, potentially impairing the absorption of the medication. Thus, levothyroxine should be taken at least 4 hours before or after taking magnesium-containing antacids (20).

Penicillamine (Cuprimine, Depen) is a medication used to treat Wilson’s Disease (copper toxicity), cystinuria, and severe rheumatoid arthritis. It works by chelating (bonding to) heavy metals (e.g., copper, mercury, lead) to form a complex that is readily eliminated via the urine (21).

However, penicillamine also binds magnesium. This could result in reduced bioavailability of the drug and diminish the effectiveness of the medication. Accordingly, magnesium supplements or antacids should be taken at least 2 hours apart from penicillamine (22).

Native Note: Long-term treatment with high-dosage penicillamine could cause magnesium depletion through its binding action (23).

Digoxin is a medication that is indicated for the treatment of heart failure and atrial fibrillation (Afib). Its primary mechanisms of action are to make the heart contract (beat) more vigorously and slow down the heart rate (24).

Digoxin can cause magnesium deficiency by reducing the reabsorption of magnesium in the kidneys (25). When the kidneys filter blood, magnesium and other substances that the body still needs are reabsorbed back into the bloodstream. This process of reabsorption is essential for maintaining healthy blood levels of magnesium (26).

Digoxin-induced depletion of magnesium is especially significant considering that low blood magnesium is linked to increased death from cardiovascular disease (27).