Can You Take Calcium and Magnesium Together?

Calcium and magnesium are minerals that play critical roles in health. Calcium provides structure to bones and is necessary for nerve function, while magnesium is needed for important processes such as blood sugar regulation and muscle contraction.

Both of these minerals are essential, meaning they must be consumed through dietary sources on a consistent basis. Magnesium and calcium are found in a number of foods, but factors such as dietary intake, medication use, and health conditions can interfere with the levels of magnesium and calcium you have, which is why some people require supplements.

While it’s safe to take magnesium and calcium supplements together, taking them separately may be the best choice. This is because when taken together, the minerals can interfere with each other's absorption.

Here’s everything you need to know about taking both calcium and magnesium supplements. 

Benefits of Calcium

Calcium is best known for its role in keeping bones strong and healthy. However, calcium is necessary for a number of other crucial processes, such as blood vessel dilation, blood clotting, and the secretion of certain hormones.

Most people get plenty of calcium from their diets, but certain populations, such as postmenopausal women and people following vegan diets, may need to take a calcium supplement to meet their daily needs.

Calcium supplements can benefit health in the following ways:

• Help improve bone mineral density: Maintaining optimal calcium status is essential for supporting skeletal health and bone mineral density. In some populations, such as middle-aged and older women, calcium supplements may help slow the rate of bone mineral density decline in the femur and spine. However, it’s unclear if calcium supplements are effective for protecting against fracture risk and osteoporosis.
• May protect against cardiovascular disease (CVD): Research has shown that calcium supplementation may decrease your risk of death from CVD. This could be because calcium may slightly adjust lipid (fat) profiles, reduce blood pressure, and decrease the risk of hypertension.
• May reduce colorectal cancer risk: Dietary calcium has been linked to a reduction in polyps in the intestines. This may be due to calcium's ability to combine with bile acids in the intestines, which can reduce the rate at which the cells of these polyps develop.
  

Benefits of Magnesium

Magnesium is concentrated in many plant foods, such as beans, seeds, and vegetables. Unfortunately, due to an overreliance on ultra-processed foods and low consumption of magnesium-containing foods, it’s estimated that around half of Americans consume less than the daily recommended amount of magnesium.

People with health conditions that impact magnesium absorption and older adults are also at greater risk for developing low magnesium levels.

Magnesium supplements are necessary for people who can’t maintain optimal magnesium status through diet alone. Plus, taking magnesium has been linked with the following health benefits: 

• May reduce blood sugar and blood pressure: Taking magnesium supplements can help support optimal blood sugar and blood pressure and can benefit people with high blood pressure (hypertension) and diabetes.
• Supports bone health: Low levels of magnesium can inhibit the formation of bone tissue and increase bone breakdown, which can increase the risk of developing bone disorders like osteopenia and osteoporosis. Research shows taking magnesium supplements may help improve bone mineral density and decrease fracture risk in certain populations. 
• May improve mental health: Research has shown that taking magnesium supplements may help reduce symptoms of depression and anxiety and help regulate stress.

Magnesium supplements have also been shown to improve sleep quality, reduce headache symptoms, and ease constipation.

Is There a Benefit To Taking Calcium and Magnesium Together?

Maintaining optimal levels of both magnesium and calcium is essential for overall health. If you have low levels of both, you might need to take both supplements. However, there might not be a benefit from taking them at the same time. Instead, you can likely get the most benefit of each supplement by taking the two separately.

Calcium and magnesium may compete for absorption in the body, so taking the supplements at the same time could interfere with your body’s ability to absorb the nutrients. Instead, it's best to take them at different times throughout the day.

If you are someone who only takes a calcium supplement, there may be a benefit to adding magnesium to your supplement regimen. High calcium intake can impair magnesium balance when magnesium intake is low. Taking a magnesium supplement in addition to the calcium supplement can avoid a disruption to your magnesium balance.

Besides providing your body with a balance of magnesium and calcium, taking the two supplements in combination can further benefit bone health, such as by increasing bone density.

How To Take a Combination of Calcium and Magnesium

It’s best to take calcium and magnesium separately whenever possible. For example, you might choose to take your magnesium supplement in the afternoon and your calcium supplement at night.

That said, some products, such as those promoted for bone health and multivitamin supplements, often contain a number of nutrients, including minerals like magnesium and calcium. To ensure the calcium is not negatively affecting magnesium absorption, the manufacturer might include a greater amount of magnesium than calcium in the product.

Make sure to follow any directions from your healthcare provider and the manufacturer.

Dosage 

Supplements that contain a combination of magnesium and calcium tend to have a 2:1 or 3:1 ratio—there is two or three times the amount of magnesium than calcium. Manufacturers of these combination supplements say these are the ideal ratios for both minerals to get properly absorbed. However, there is no official ideal ratio.

Most multinutrient supplements provide 200-300 milligrams (mg) of calcium. That's less than calcium-only supplements, which typically contain 500-600 mg of calcium per dose but can contain as much as 1,500 mg.

The amount of magnesium a supplement contains varies and can be especially dependent on the type of magnesium used.

How much magnesium and calcium you need each day depends on factors like age, sex, and pregnancy status. It’s recommended that adults take 310-420 mg of magnesium and 1,000-1,300 mg of calcium per day. Keep in mind these recommendations are for total dietary magnesium and calcium intake, including amounts found naturally in food and from dietary supplements.

The supplemental dosage you need—and for how long you take it at that dose—can depend on your current levels of the minerals as well as factors like your diet.

Is It Safe To Take Magnesium and Calcium Together?

It’s safe to take magnesium and calcium together. However, to enhance the absorption of these minerals, it’s best to take them separately.

Other than the decreased absorption that may occur due to competing absorption, there are no significant health concerns related to taking magnesium and calcium together. 

While taking both supplements as part of your regimen is fine, you should always consider the safety of each individual supplement. For instance, calcium supplements have been linked to an increased risk of heart disease and kidney stones, especially when taken in high doses. And taking large doses of magnesium can lead to diarrhea, nausea, and abdominal cramping.

Serious side effects are rare for either supplement, and they are likely safe even during pregnancy when taken at the right amount.

Potential Drug Interactions

Before taking any new supplement, you should check with your healthcare provider about what interaction it might have with any medication or supplement you are already taking.

Calcium supplements may interfere with the following medications:

• Tivicay (dolutegravir): Taking calcium with this HIV medication may significantly decrease blood levels of the medicine. It’s recommended to take dolutegravir at least two hours before or six hours after taking calcium supplements.
• Thyroid medications: Calcium supplements may interfere with the absorption of levothyroxine, sold under brand names like Synthroid and Levoxyl, a medication used to treat hypothyroidism and thyroid cancer. The medication should be taken at least four hours apart from calcium.
• Antibiotics: Calcium supplements may reduce the absorption of certain antibiotics, such as Cipro (ciprofloxacin) and Factive (gemifloxacin). These medications should be taken two hours before or two hours after calcium supplements. 

Magnesium supplements may interfere with the following medications:

• Antibiotics: Magnesium supplements may decrease the absorption of some antibiotics, such as doxycycline (sold under brand names like Vibramycin and Monodox) and ciprofloxacin. Antibiotics should be taken two hours before or at least four hours after taking a magnesium supplement.
• Bisphosphonates: These drugs, including Fosamax (alendronate), can help treat osteopenia or osteoporosis. Magnesium supplements may interfere with the absorption of the drug, so they should be taken at least two hours apart.
• Diuretics: Certain diuretics—namely potassium-sparing ones like Midamor (amiloride) and Aldactone (spironolactone)—reduce how much magnesium is excreted through urine. This can lead to an increase in magnesium levels that, combined with magnesium supplements, can make your magnesium levels too high.

What To Look For 

When shopping for magnesium and calcium supplements, there are a few factors to consider. To ensure you’re purchasing a high-quality and safe supplement, choose supplements from reputable manufacturers. 

Whenever possible, purchase magnesium and calcium products that are certified by USP, UL, or NSF International. These independent organizations set strict standards for supplement quality and safety.

It’s also important to choose supplements in a form you can tolerate. If you have trouble swallowing capsules or tablets, consider taking a liquid, chewable, or powdered supplement. 

If your healthcare provider determines supplementing with both magnesium and calcium is appropriate for you and you want to take a combination supplement, ask them what ratio of magnesium to calcium would be best and look for that ratio on the packaging.

Can You Take Too Much Calcium or Magnesium?

While it’s safe to ingest high amounts of calcium and magnesium from food sources, it is possible to take in too much of these nutrients from supplements.

The maximum amount of magnesium supplements considered safe for most adults to take each day is 350 mg. The maximum amount of calcium intake across all forms—supplements, food, and drink—considered safe for most adults is 2,000-2,500 mg each day.

Taking magnesium supplements that contain doses higher than the maximum recommended amount can be safe, but taking very large doses of magnesium-containing laxatives and antacids—doses as big as 5,000 mg a day—has been associated with magnesium toxicity. The risk is higher for people with impaired kidney function. Symptoms of magnesium toxicity include low blood pressure, difficulty breathing, and irregular heartbeat.

Taking very high doses of calcium can also harm health, including the health of the cardiovascular system. High supplemental calcium intake can cause extra calcium to be deposited in your arteries, which can increase the risk of heart disease and cardiovascular complications like heart attack.

For example, a 2021 review of 13 studies that included 43,178 people found that supplementary calcium intake of 1,000 mg per day significantly increased the risk of heart disease by about 15% among healthy postmenopausal women.

Side Effects of Taking a Combination of Magnesium and Calcium

Calcium and magnesium can lead to different side effects, including gastrointestinal upset. 

Some of the most common side effects of taking magnesium supplements include diarrhea, nausea, and mild abdominal pain. Keep in mind that certain forms of magnesium, like magnesium oxide, are more likely to cause gastrointestinal side effects compared to other forms, such as magnesium glycinate. 

Calcium supplements may also lead to gastrointestinal symptoms. For example, calcium carbonate, a common form of calcium used in supplements, may lead to bloating, gas, and constipation. Taking calcium with food may reduce the risk of experiencing these uncomfortable side effects. 

Because certain forms of magnesium and calcium may trigger gastrointestinal symptoms, taking the nutrients together may exacerbate these side effects.

In addition to digestive symptoms, some research suggests that taking high-dose calcium supplements may lead to other negative health consequences, such as kidney stones, age-related macular degeneration, heart disease, and metabolic syndrome.

A Quick Review

Magnesium and calcium are minerals that play essential roles in health. Sometimes, a healthcare provider may determine you need to increase or maintain your levels of both through supplements. Magnesium and calcium supplements may offer several health benefits. For example, both have been linked to improved bone health. But magnesium and calcium may negatively affect each other's absorption, so talk with your healthcare provider about when to take each supplement and how much of each to take so you can get the most benefit out of each.