How Long Does Magnesium Stay in Your Body?

Magnesium is an essential mineral that helps your body function properly, from supporting muscles and nerves to keeping your heartbeat steady.

How long it stays in your system depends on a few factors, but most types of magnesium are cleared within a day or two.

How Long Magnesium Lasts in Your Body

If you take magnesium supplements or eat magnesium-rich foods, about half of it will still be in your system eight to nine hours later. After another eight to nine hours, half of that amount (25%) will remain. This cycle continues until the magnesium is mostly cleared.

Your body doesn’t eliminate magnesium all at once. Some of it is stored in your bones and muscles, where it can remain for weeks or even months, depending on your needs and how quickly your body uses it.

Factors That Can Affect How Long Magnesium Remains in Your Body

1. The Form of Magnesium

Magnesium supplements come in several forms, each absorbed differently by the body. Many foods also naturally contain magnesium in different forms.

Common types of magnesium include:

Forms like citrate, glycinate, aspartate, and lactate tend to be absorbed more efficiently, which may keep magnesium circulating in the bloodstream longer.

On the other hand, forms like magnesium oxide are absorbed less effectively, meaning they raise magnesium levels less and may be excreted more quickly.

While supplement labels usually list the form they contain, eating a range of magnesium-rich foods can help you get magnesium in different forms.

2. How Much Magnesium You Take

Higher doses of certain forms, like magnesium citrate, can lead to greater absorption.
Supplements typically range from 100 to 400 milligrams or more, usually taken once daily.

The Recommended Dietary Allowance (RDA) for magnesium is:

• 400–420 milligrams per day for men
• 310–320 milligrams per day for women

3. Your Current Magnesium Levels

If your magnesium levels are low, your body will hold on to more of it. But if you already have enough, excess magnesium is usually excreted through urine.

Your body does a great job regulating magnesium levels to maintain balance. A healthy, balanced diet and incorporating various magnesium-rich foods can help ensure your magnesium levels are healthy.

4. Health Conditions and Medications

Certain health issues can affect how well your body absorbs and holds onto magnesium. A few conditions might make it harder for your body to hold on to magnesium.

For example:

Some medications can also reduce magnesium absorption, including:

Side Effects and Safety Considerations

Getting too much magnesium from food is rare and not usually a big concern. But high doses from supplements can lead to side effects like diarrhea, nausea, and stomach cramping.

In rare cases, magnesium toxicity has occurred from taking extremely high doses over time.

It’s a good idea to check with your doctor before taking magnesium supplements, especially if you’re on medications like blood pressure drugs, antibiotics, bisphosphonates, diuretics, or PPIs.