5 Medications You Shouldn’t Mix with Magnesium

Does your daily routine include a handful of supplements? If magnesium is in the mix, you’re not alone. This essential mineral seems to be becoming part of many peoples’ routines, promising to ease muscle cramps, help you sleep better and even support your bone health. “Some research suggests that magnesium can be useful for the prevention of high blood pressure, type 2 diabetes, osteoporosis, migraine headaches and to help improve sleep,” per Cathryn Williamson, PharmD. But before you take that next capsule, there’s something you might not know: magnesium can have an impact on certain medications in ways that aren’t always obvious. Mixing the wrong combo could mean your medicine won’t work as well, or you might end up with some unpleasant side effects.

Curious which medications clash with magnesium? You’re in the right place. We’ll break down five you should definitely avoid mixing, plus offer simple tips to keep your supplement routine smart and safe.

1. Antibiotics

“One of the main class of medications that ranks highest in terms of clinically significant interactions with magnesium is antibiotics, specifically the fluoroquinolones (like ciprofloxacin, levofloxacin) and tetracyclines (like doxycycline, minocycline). This interaction is considered highly important because magnesium binds to these antibiotics in the gut, forming insoluble complexes and dramatically reducing their absorption and effectiveness,” shares Raksha Shah, M.A., RDN.

If you’re prescribed antibiotics, it’s best to take magnesium supplements at least two to six hours before or after taking the medication. Spacing doses out like this helps ensure the drug has enough time to be absorbed properly. Always talk to a healthcare provider if you have questions or need individualized advice. 

2. Osteoporosis Medications

“While magnesium deficiency is associated with osteoporosis, oral magnesium can decrease the absorption of some medications designed to treat the condition, such as alendronate,” explaines Daniel Atkinson, MD. Similar to antibiotics, magnesium may interfere with the absorption of these medications in the digestive tract. This could reduce the efficacy of the treatment and potentially compromise bone health in the long term.

It is generally recommended to take bisphosphonates like alendronate on an empty stomach with water and avoid magnesium-containing supplements or antacids for at least 30 to 60 minutes after taking the medication. Always follow the specific instructions provided with your prescription for best results.

3. Blood Pressure Medications

Some blood pressure medications, particularly calcium channel blockers (e.g., amlodipine), can have interactions with magnesium. “Amlodipine is a calcium channel blocker, and magnesium can also work in this way. So taking both at the same time can potentially amplify this effect and cause your blood pressure to drop too low,” per Atkinson. This has the potential to lead to excessively low blood pressure. This may result in symptoms like dizziness, fainting or even more serious cardiovascular complications. 

If you’re taking blood pressure medication, consult a healthcare provider before starting a magnesium supplement. They may recommend monitoring your blood pressure more closely or adjusting your magnesium intake so that it aligns safely with your treatment plan.

4. Diuretics

Diuretics—sometimes called “water pills”—are often prescribed for high blood pressure, heart failure or kidney issues. There are two primary types of diuretics that interact differently with magnesium:

• Loop and thiazide diuretics (e.g., furosemide or hydrochlorothiazide) can cause magnesium depletion in your body. Taking a magnesium supplement may be beneficial in such cases but should still be monitored closely by a physician.
• Potassium-sparing diuretics (e.g., spironolactone) “can increase magnesium levels dangerously when combined with magnesium supplements,” per Shah. Adding a magnesium supplement on top of this could lead to hypermagnesemia (too much magnesium in the body), with symptoms ranging from nausea to slowed heart rate.

Work with a healthcare provider to track your magnesium levels if you’re on a diuretic. Depending on your specific prescription and health needs, they can advise whether magnesium supplements are safe or necessary for you.

5. Amphetamines

Magnesium can impact the absorption and effectiveness of amphetamines, such as those prescribed for ADHD (e.g., Adderall) or narcolepsy. “Magnesium can change the pH of the stomach and cause a more basic environment (higher pH). Some drugs like amphetamines require an acidic environment for proper absorption. In the case of amphetamines, higher pH can cause the drug to be released faster into the body and possibly cause more side effects,” per Williamson. This can potentially reduce the intended stimulant effects or, in some cases, make the medication act unpredictably.

If you take amphetamines, consult a healthcare provider before starting magnesium supplements. They may recommend spacing out the timing of your medication and magnesium by at least a couple of hours to avoid interference. Always follow the provider’s advice to ensure your medication continues to work as intended.

Potential Symptoms of a Reaction

When medications interact with magnesium in a harmful way, your body often gives off warning signs. If you notice any of the following symptoms, consult a healthcare professional as soon as possible:

• Vomiting: Persistent nausea or vomiting could suggest an adverse reaction to a magnesium-medication combination. 
• Fatigue: Excessive tiredness or weakness might indicate that magnesium is amplifying the effects of a medication, such as lowering blood pressure too much. 
• Heart rate irregularities: Symptoms like a slow or irregular heartbeat could point to elevated magnesium levels in your bloodstream, especially if you’re taking medications that already affect heart function. 

And generally, if your medication is not working in the way you expect, like if you still have a bacterial infection after taking your course of antibiotics, it may be a sign that you were taking your magnesium too close to your antibiotic administration. Always pay close attention to how your body responds when starting or changing a supplement or medication regimen.

Our Expert Take

Magnesium is undoubtedly important for overall health and can provide numerous benefits when taken appropriately. However, it’s equally crucial to understand its potential interactions with other medications. If you take any of the drugs mentioned above, or any other prescription, discuss magnesium supplementation with a healthcare provider. They can offer personalized advice tailored to your health needs, including timing recommendations or alternative approaches to achieve your wellness goals.

By staying informed and proactive, you can maximize the benefits of both your medications and your magnesium supplement while minimizing the risks.