Can You Take Iron and Magnesium Together?
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Medically reviewed by Suzanne Fisher, RD
Iron and magnesium are both critical minerals your body uses for many purposes. Getting enough iron is important for preventing anemia, a condition in which you don’t have enough healthy red blood cells. Getting enough magnesium can help keep your cardiovascular and nervous systems functioning properly.
Some people might not get enough iron and magnesium through their diet. Deficiencies in magnesium are common in the U.S. As for iron, children and women of childbearing age are particularly prone to not getting enough.
A healthcare provider may determine that taking supplements for both iron and magnesium makes sense for your health. While you can take iron and magnesium together, it’s important to be thoughtful about dose and potential interactions with medications.
Benefits of Iron
Iron is a critical mineral for many bodily processes, but it is especially important in preventing anemia. If you don’t have enough iron, your body may not be able to make hemoglobin, a protein needed for healthy red blood cells. This can lead to iron deficiency anemia. You may develop anemia if you lose blood, you aren’t getting enough iron in your diet, or both.
If you have anemia from an iron deficiency, taking extra iron can help. A healthcare provider can use blood tests to check your iron and tell you how much iron you should take and for how long.
Iron is primarily known for its role in preventing anemia. However, it performs lots of other roles. For example, iron is involved in promoting physical growth, enhancing brain development, synthesizing some hormones, and fortifying the immune system. Problems in these areas don’t tend to be as obvious unless you have a severe iron deficiency. Children might be particularly more vulnerable to these sorts of problems from severe iron deficiency.
Benefits of Magnesium
Magnesium is a multifunctional mineral involved in both DNA and protein synthesis, as well as calcium regulation. Magnesium plays particularly important roles in your muscles, the cardiovascular system, and the nervous system.
If severe, a magnesium deficiency can lead to problems like depression, fatigue, muscle weakness, and even seizures or abnormal heart rhythms (arrhythmia). Taking in enough magnesium can prevent these complications.
While severe deficiency is not common, milder magnesium deficiency is. Researchers have studied whether having a milder deficiency might also contribute to various medical conditions and, in turn, whether keeping magnesium levels regular can prevent these complications.
For example, some evidence has shown that getting enough magnesium might help lower high blood pressure (hypertension). Other promising studies have explored potential roles of proper magnesium levels in avoiding the heightened risk of diabetes and osteoporosis low magnesium levels may pose.
Researchers have also studied the potential beneficial impact of magnesium in conditions such as migraine, insomnia, asthma, and epilepsy. But so far, these results have been inconclusive.
Benefits of Taking Iron and Magnesium Together
It may make sense for some people to take both iron and magnesium supplements, especially if they are deficient in both and unable to get enough of either through their diet.
This might especially be the case for people who have anemia from iron deficiency. Although the evidence for this is evolving, anemia may be more common among people who don't get enough magnesium. For people who are deficient in iron and magnesium, treating anemia might be more effective if you take both supplements.
People who are deficient in one vitamin or mineral are often deficient in others. For example, certain medical conditions—like those of the digestive tract that make it harder for you to absorb vitamins and minerals—might put you at risk of deficiencies in both iron and magnesium. So some people with certain conditions might need supplements for both.
How To Take a Combination of Iron and Magnesium
Iron and magnesium are often taken as pills, but some other formulations, like powders, are sometimes available.
You typically need to purchase two separate supplements if you want to take iron and magnesium. However, some multivitamins contain both iron and magnesium, particularly vitamins marketed toward women.
Taking a lot of magnesium may interfere with the absorption of iron, though this may not be a problem at lower doses. You could choose to take iron and magnesium at the same time or not.
You might lower your risk of stomach upset from iron if you take it right after a meal. Some people also like to take magnesium right before bed because it can give a relaxing effect.
Related: Should You Take Magnesium for Sleep?
Dosage
There's no set dosage for how much iron and magnesium you should have when taking them together. When you and your healthcare provider are choosing a dosage, you will likely take into account factors like your age, sex, and current blood levels of the nutrients.
They will also factor in how much you're already taking in from your diet. There are recommended amounts for how much iron and magnesium someone should take in from all sources, including diet and supplements.
The recommended iron dosage differs based on a person’s age and sex. A big part of this is because of menstruation. People who menstruate lose blood and iron regularly, so they need more iron through their diet—and potentially supplements.
The recommended daily allowance (RDA) for men 19 or older and women 51 or older is 8 milligrams (mg). The RDA for iron is 15 mg for girls aged 14-19 and 18 mg for women aged 19-50. During pregnancy, the RDA for iron is 27 mg.
Because of the way different types of iron are absorbed from different foods, vegetarians actually may need to take in higher amounts of iron. For example, a 25-year-old vegetarian woman might have an RDA closer to 32 mg.
Keep in mind that iron sold as over-the-counter (OTC) supplements typically contain doses larger than the RDA for most people. And some multivitamins contain more iron than is recommended, especially if you are a woman who has not yet gone through menopause. Speak with a healthcare provider about the right dosage for you.
For magnesium, the RDA is 400 mg for men aged 19-30 and 310 mg for women in the same age range. For people aged 31 or older, iron's RDA is 420 mg for men and 320 mg for women. For comparison, many OTC supplements contain about these amounts. Again, you'll need to speak with your healthcare provider about the dose you need and for how long.
Is It Safe to Take Iron and Magnesium?
If you haven’t been getting enough iron and magnesium, it’s generally safe to take them both in supplement form. There doesn't appear to be any negative reaction between the two supplements. However, you want to be sure that supplementation is really the right way to go.
Taking the amount of magnesium in a multivitamin is safe for almost everyone. Most people could also safely take the amount of magnesium present in most supplements. However, people with certain medical conditions, like severe kidney disease or Addison’s disease, need to be more cautious.
You want to get enough iron, but getting too much has its risks. Most people don’t need to take separate supplements containing iron. And most men and older women don’t even need the amount of iron contained in multivitamins. Check with a healthcare provider to see if you need iron supplements.
Potential Drug Interactions
Some drugs may interfere with the absorption of magnesium, iron, or both. Other drugs may interact with the supplements in a way that increase the nutrients' amounts in your body. Sometimes taking extra magnesium or iron might increase the risk of side effects from a drug or make the drug less effective.
The following are some drugs that iron and/or magnesium may interact with:
Antacids containing magnesium, like Maalox
Antibiotics, including quinolones like Cipro (ciprofloxacin), tetracyclines like Doxycycline (doxycycline), and aminoglycosides like Garamycin (gentamicin)
Drugs that affect blood clotting, such as Plavix (clopidogrel)
Drugs to treat osteoporosis, such as bisphosphonates like Actonel (risedronate)
Some drugs to treat high blood pressure, such as calcium channel blockers like Norvasc (amlodipine)
Potassium-sparing diuretics like Aldactone (spironolactone), which might increase magnesium
Drugs for gastroesophageal reflux disease (GERD), such as proton pump inhibitors like Prilosec (omeprazole)
You still may be able to take the drugs safely, but you should check with a healthcare provider or pharmacist on how to minimize any risk.
What To Look For
You can purchase OTC iron supplements in different formulations, including ferrous sulfate, ferrous gluconate, and ferrous fumarate. Enteric formulations and slow-release formulations may be a little easier on the stomach than other kinds, but dose is the most important factor in reducing side effects.
Similarly, magnesium is available in different formulations, including magnesium citrate, magnesium oxide, and magnesium glycinate.
If you want to get iron and magnesium through a multivitamin, look carefully at the label. Many multivitamins don’t contain any iron, particularly gummy vitamins.
If you are purchasing a product OTC, look for a label indicating the product has been tested by a third party. Because the U.S. Food and Drug Administration doesn't regulate supplements the same way it does medication, third-party testing can help ensure the product is good quality.
Your healthcare provider or pharmacist may also make specific recommendations that you will want to look for when making a purchase.
Related: Which Type of Magnesium Is Best?
Can You Take Too Much Iron or Magnesium?
You can take too much of iron or magnesium.
Taking too much iron can be particularly toxic. Many young children have overdosed from taking too many multivitamins that contained iron. Taking over 20 mg per kilogram of body weight can lead to severe and even deadly symptoms.
Iron toxicity can also happen if you take smaller amounts over a prolonged time, especially if you didn’t have a true iron deficiency. Over time, the extra iron can cause problems like liver damage, fatigue, joint pain, and increased blood glucose.
Per government recommendations, you should get not more than 45 mg of total iron daily, including from both food and supplements. You might need to take more temporarily if you've been diagnosed with iron deficiency, though.
If you take very high doses of magnesium, it can cause serious symptoms of magnesium toxicity. For example, at high doses (more than 5,000 mg), you might develop muscle weakness, difficulty breathing, low blood pressure, vomiting, and arrhythmia.
You shouldn't take more than 350 mg per day in magnesium supplements (though your total intake with food might be higher). People with certain medical conditions, like kidney disease, should be more cautious.
Additionally, taking a lot more magnesium than you need may have a counterproductive effect on iron deficiency. For example, if you were taking too much magnesium in the form of a laxative, it might actually worsen anemia.
Side Effects of Taking a Combination of Iron and Magnesium
If taken at very high doses, both iron and magnesium can cause serious problems from toxicity. However, other side effects are possible even if you're taking lower doses.
For iron, gastrointestinal side effects are quite common. Abdominal pain, constipation, diarrhea, nausea, and vomiting can all occur.
The most common side effects from magnesium are very similar, often causing symptoms like diarrhea and upset stomach.
Scientists haven’t specifically studied side effect profiles when the two are combined.
A Quick Review
Iron and magnesium are both critical minerals you need for good health. While some people get enough of the two nutrients through their diets, a healthcare provider may determine you need to increase your levels by taking supplements for both iron and magnesium. While you can take iron and magnesium together, you will want to check with a healthcare provider about the potential risks and benefits.
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