Disclaimer: None of the information in this article constitutes medical advice. All statements are merely the opinion of the writer(s). We recommend that patients follow their doctor’s guidance in regard to supplementation.
Magnesium is one of the most commonly-supplemented minerals, and for good reason. As we documented in our article on the best magnesium supplements, this mineral has a host of potential cardiovascular and metabolic benefits.
But how long does it take you to start noticing an effect after starting a magnesium supplement? Does it vary based on your health status and condition? Does topical magnesium work more rapidly than oral magnesium based on our personal tests?
In this article we'll answer all of these questions and more, as we analyze clinical studies on magnesium supplementation to determine how long the compound takes to have an effect.
We'll discuss how and why the time window may vary by person, and share our experience testing oral and topical magnesium.
Key takeaways:
- Research studies suggest it takes around eight weeks for a notable effect
- Taking magnesium citrate may cause quicker absorption
- Our personal tests found that topical magnesium worked quicker than oral
What Does the Research Say?
There have been hundreds of clinical trials on oral magnesium supplementation.
A published in the Magnesium Research journal found that oral magnesium supplementation alleviated low magnesium status after seven weeks.
As we documented in our magnesium glycinate vs citrate article, another study reported that around eight weeks of supplementation increased magnesium levels in the body.
A 2014 found that 12 weeks of magnesium supplementation improved physical performance in elderly women.
Based on the available research, it seems that around eight weeks of oral supplementation is necessary to have a noticeable effect, on average.
Is Topical Magnesium Faster-Acting?
Magnesium oil (magnesium chloride and water) may potentially be faster-acting than oral magnesium, because it appears to be absorbed directly into the bloodstream through the skin.
There are significantly fewer clinical trials on topical magnesium than oral magnesium, but a published in the Nutrients journal documented a few clinical trials which found this method to be effective.
As the author of this article, I've tried both forms of magnesium (and have been diagnosed in the past with a mild intracellular magnesium deficiency), and topical magnesium oil had the most immediate effect in my experience:

After 2-4 sessions of topical magnesium a few days in a row, I noticed reduced muscle tension and greater relaxation.
The downside to this approach is that it's highly inconvenient and irritates the skin. I definitely recommend purchasing some body lotion in advance of using this type of product regularly.
Should I Test Before Supplementing?
Ordering a magnesium test may make sense prior to supplementation, since magnesium supplements would be a waste of money for individuals already replete in the mineral.
An intracellular nutrient test is generally more accurate than a typical blood test for magnesium, because 99% of magnesium in the body is stored in tissue and bone, not in the blood (source).
Unfortunately, this type of testing is rarely covered by health insurance in the US.
As the author of this article, I had to pay for this test out-of-pocket when I got it done years ago.