Magnesium is an important mineral that plays a role in over 300 biochemical reactions in the body. It helps regulate blood pressure, blood sugar levels, nerve functioning, energy production, muscle and nerve function, protein synthesis and more. Magnesium supplements are often taken to help prevent magnesium deficiency or treat conditions like constipation, insomnia, leg cramps, migraines and more.
While generally well tolerated, magnesium can interact with certain medications. Taking magnesium alongside some medications can make the drugs less effective or increase the risk of side effects. For this reason, it’s important to know what medications should not be taken at the same time as magnesium.
Diuretics
Diuretics, also called water pills, work by increasing urination to remove excess fluid from the body. They are often prescribed to treat high blood pressure, heart failure, liver cirrhosis, kidney disease and certain types of edema.
Some examples of diuretics include:
- Furosemide (Lasix)
- Hydrochlorothiazide
- Spironolactone (Aldactone)
- Triamterene (Dyrenium)
Magnesium can decrease the effectiveness of diuretics. It works opposite to diuretics by drawing water into the intestines, which decreases urine output.
If you need to take magnesium, make sure to take it at least 2 hours before or 4–6 hours after taking diuretic medications.
Antibiotics
Taking magnesium with certain antibiotics can prevent the drugs from being properly absorbed and utilized by the body.
Some examples of antibiotics that interact with magnesium include:
- Ciprofloxacin (Cipro)
- Doxycycline
- Levofloxacin (Levaquin)
- Minocycline
- Tetracycline
To prevent issues, avoid taking magnesium supplements within 2 hours of taking these antibiotics.
Bisphosphonates
Bisphosphonates are a class of drugs used to treat osteoporosis and other bone conditions characterized by loss of bone density.
Examples include:
- Alendronate (Fosamax)
- Ibandronate (Boniva)
- Risedronate (Actonel)
- Zoledronic acid (Reclast, Zometa)
Calcium, iron, magnesium and other minerals can bind to these drugs in the digestive tract, preventing absorption. To prevent this interaction, wait at least 30 minutes after taking an oral bisphosphonate before consuming mineral supplements like magnesium.
Antibiotics for Tuberculosis
Magnesium shouldn’t be taken with antibiotics used to treat tuberculosis, such as:
- Ethambutol (Myambutol)
- Isoniazid (Nydrazid, Laniazid)
- Rifampin (Rifadin, Rimactane)
- Pyrazinamide
These medications interact with magnesium in a way that can increase the risk of central nervous system side effects like anxiety, depression and confusion.
To be safe, avoid taking magnesium supplements if you are taking antibiotics to treat tuberculosis.
Muscle Relaxants
Muscle relaxants are used to treat muscle spasms, pain and discomfort. Some examples include:
- Cyclobenzaprine (Flexeril)
- Carisoprodol (Soma)
- Metaxalone (Skelaxin)
- Methocarbamol (Robaxin)
- Tizanidine (Zanaflex)
Magnesium can enhance the effects of muscle relaxants, causing excessive sedation and weakness.
Avoid taking magnesium within 1–2 hours of muscle relaxants unless approved by your healthcare provider.
Digoxin
Digoxin (Lanoxin) is a medication used to treat heart failure and atrial fibrillation. It works by making the heart beat stronger and with a more regular rhythm.
Taking digoxin along with magnesium can increase digoxin levels in the body. This puts you at risk of digoxin toxicity, with symptoms like nausea, vision changes and abnormal heart rhythms.
It’s recommended to avoid taking magnesium supplements if you use digoxin unless approved by your doctor. Magnesium from food sources is less likely to interact.
Blood Pressure Medications
Magnesium may interact with certain blood pressure medications, including:
- ACE inhibitors like lisinopril (Prinivil, Zestril), benazepril (Lotensin), captopril (Capoten) and enalapril (Vasotec)
- Angiotensin II receptor blockers (ARBs) like losartan (Cozaar) and valsartan (Diovan)
- Calcium channel blockers like amlodipine (Norvasc), diltiazem (Cardizem) and nifedipine (Procardia)
Using magnesium with these drugs can sometimes result in elevated magnesium levels, which may cause side effects like low blood pressure, nausea, vomiting, fatigue and confusion.
If you take these blood pressure medications, talk to your healthcare provider before starting magnesium supplements.
Antidepressants
Magnesium may interact with certain antidepressant medications like:
- Citalopram (Celexa)
- Escitalopram (Lexapro)
- Fluoxetine (Prozac)
- Sertraline (Zoloft)
In particular, SSRIs like these can cause high magnesium levels when taken with magnesium supplements. Symptoms of magnesium toxicity can include lethargy, impaired breathing, low blood pressure and dangerous heart rhythm changes.
Avoid magnesium supplements if you take these antidepressants unless monitored closely by your doctor.
Antacids
Some examples of antacids that may interact with magnesium include:
- Aluminum hydroxide (Amphojel)
- Calcium carbonate (Tums, Os-Cal)
- Dihydroxyaluminum sodium carbonate (Rolaids)
- Magaldrate (Riopan)
- Magnesium hydroxide (Milk of Magnesia)
- Sodium bicarbonate (baking soda)
Using magnesium supplements with magnesium-containing antacids can potentially lead to overdose. Additionally, antacids can sometimes cause diarrhea, which may increase magnesium loss in the stool.
Avoid taking magnesium supplements within 2 hours of antacids unless directed by your doctor.
Laxatives
Some laxatives that can interact with oral magnesium supplements include:
- Stool softeners like docusate (Colace)
- Osmotic laxatives like milk of magnesia, magnesium citrate and polyethylene glycol (MiraLax)
- Stimulant laxatives like bisacodyl (Dulcolax)
Using magnesium supplements alongside laxatives may increase the risk of hypermagnesemia or magnesium overdose. Symptoms can include nausea, vomiting, severely low blood pressure and irregular heartbeats.
It’s best to avoid taking magnesium supplements within 2 hours of using magnesium-based laxatives.
Gabapentin
Gabapentin (Neurontin) is an anticonvulsant drug used to prevent seizures and treat neuropathic nerve pain.
Magnesium can bind to gabapentin in the digestive tract, reducing its absorption and effectiveness. Waiting at least 2 hours between taking gabapentin and magnesium supplements can help minimize this interaction.
Quinolone Antibiotics
Examples of quinolone antibiotics that should not be taken with magnesium include:
- Ciprofloxacin (Cipro)
- Gemifloxacin (Factive)
- Levofloxacin (Levaquin)
- Moxifloxacin (Avelox)
- Ofloxacin (Floxin)
These antibiotics can form insoluble complexes when taken at the same time as magnesium, reducing absorption of the medication.
To prevent this interaction, avoid taking magnesium supplements within 2 hours of quinolone antibiotics.
Sodium Polystyrene Sulfonate
Sodium polystyrene sulfonate (Kayexalate) is a medication used to treat high potassium levels. It works by binding to potassium and removing it from the body.
Sodium polystyrene sulfonate may also bind to magnesium, leading to low magnesium levels.
Taking magnesium supplements is not recommended in people using sodium polystyrene sulfonate unless approved by a doctor.
Penicillamine
Penicillamine is used to treat Wilson’s disease, rheumatoid arthritis and cystinuria. It works by binding to copper and allowing it to be removed from the body in urine.
Penicillamine can also bind to magnesium, causing magnesium loss. This may result in magnesium deficiency over time.
If you take penicillamine, talk to your doctor before starting magnesium supplements.
Tetracycline Antibiotics
Some tetracycline antibiotics that interact with magnesium include:
- Demeclocycline (Declomycin)
- Doxycycline (Vibramycin, Monodox)
- Minocycline (Minocin, Solodyn)
- Oxytetracycline (Terramycin)
- Tetracycline (Sumycin, Achromycin)
Magnesium binds to tetracyclines in the digestive tract, reducing their absorption and effectiveness as antibiotics. To prevent this, avoid magnesium supplements within 2 hours of taking these medications.
Chemotherapy Drugs
Some chemotherapy medications that shouldn’t be taken with magnesium include:
- Cisplatin
- Doxorubicin (Adriamycin)
- Vincristine (Oncovin)
- Etoposide (VP-16)
Magnesium may inhibit cell uptake of these chemotherapy drugs, reducing their anti-cancer effects. It’s best to avoid magnesium supplements during chemotherapy cycles using these medications.
Calcineurin Inhibitors
Calcineurin inhibitors like cyclosporine (Neoral, Gengraf) and tacrolimus (Prograf) are commonly used after organ transplants to prevent rejection.
Magnesium can significantly increase blood levels of calcineurin inhibitors, raising the risk of toxicity and kidney damage.
Using magnesium supplements with these medications should be carefully monitored by your transplant team.
Summary Table
Here is a summary of the main types of medications that should not be taken with magnesium:
| Type of Medication | Examples |
|---|---|
| Diuretics | Furosemide, hydrochlorothiazide, spironolactone |
| Antibiotics | Ciprofloxacin, doxycycline, tetracycline |
| Bisphosphonates | Alendronate, risedronate |
| TB Antibiotics | Isoniazid, rifampin |
| Muscle Relaxants | Cyclobenzaprine, carisoprodol |
| Digoxin | Lanoxin |
| Blood Pressure Medications | Lisinopril, amlodipine |
| Antidepressants | Citalopram, fluoxetine |
| Antacids | Calcium carbonate, magnesium hydroxide |
| Laxatives | Magnesium citrate, bisacodyl |
The Bottom Line
Magnesium supplements can interact with a variety of common medications. This may reduce the effectiveness of these drugs, increase side effects or lead to magnesium toxicity.
To avoid issues, don’t take magnesium supplements within 1-2 hours of interacting medications unless approved by your doctor. Be sure your doctor is aware of any supplements you are taking.
Pay close attention to potential signs of magnesium toxicity, including nausea, vomiting, severely low blood pressure and abnormal heart rhythms. Seek medical attention if you experience these symptoms.
With appropriate precautions, magnesium supplements can often be used safely alongside medications. But it’s important to consult your doctor to prevent potential interactions.
