JSYK, Timing Is *Key* When Taking a Magnesium Supplement

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At this point, you've probably been hearing so much about magnesium, aka that essential mineral that has likely been showing up all over your social media lately. It's naturally in a ton of the foods we eat, like green leafy vegetables, nuts, seeds, legumes, and whole grains, but a ton of people don’t get enough magnesium from grub alone. Because of that, seeking out a magnesium supplement is pretty common.

But magnesium supplements aren't just for deficiencies. There are many different formulations of magnesium and they all do various things, like helping with constipation and migraines. Some claim to also potentially aid in depression management and insomnia. And these days, the supplements don't just come in pill form—you can also get them as a powder or even a topical, like a lotion, oil, soap, or spray (but more on that later!). And don't forget about bath salts—Epsom salt contains magnesium too.

Whether you’re already in a fully committed relationship with your magnesium supplement or you’re thinkin' about starting one, taking it at the right time—especially depending on the condition you're using it for—is super important. Below, we tapped two nutrition experts to give the full scoop on the best time to take a magnesium supplement, how much of it to take, and what specific things it can treat.

So, why do you even need magnesium?

Well, magnesium supports your body in hundreds of ways. Literally. Per the National Institutes of Health Office of Dietary Supplements, it impacts over 300 systems and chemical reactions that aid in various bodily functions, like how our nerves work and blood sugar control. It's also important in helping your body in muscle contraction and relaxation, bone health, blood pressure, heartbeat regulation, electrolyte balance, insulin sensitivity, and metabolizing vitamin D, says Esther Tambe, MS, RD, CDN, CDCES, owner and founder of Esther Tambe Nutrition. These are all basic functions of magnesium.

If all of this sounds Very Important, it's because it is. A magnesium deficiency can cause some truly unpleasant (and sometimes even dangerous) symptoms, like muscle cramps, fatigue, poor sleep, nausea, tingling, and abnormal heart rhythms, adds Tambe. That being said, taking a magnesium supplement might be therapeutic for certain health concerns—like sleep issues, constipation, migraines, and mental health—which we’ll get into soon.

Do topical magnesium formulas (like oils and lotions) actually work?

Anecdotally, magnesium oils, sprays, and lotions have been getting a lot of love on TikTok with folks saying they've helped with migraines, anxiety, and sleep issues. People on the platform talk about spraying it on certain areas, like the bottoms of feet or near the armpits, or rubbing it all over, like any other lotion. So if you've been #influenced, I get it—but also, you might wanna hold on a sec. Studies have found that topical forms of magnesium don't raise magnesium levels in the body very much.

The oh-so-popular epsom salt bath doesn’t even have much research into its health benefits other than studies showing that baths in general are relaxing. Experts aren’t sure how much magnesium we really soak up through an epsom salt bath, but based on research on other topical forms of magnesium, the answer is probably not much. So if you're looking for a real boost to your magnesium levels, food sources or oral supplements are the way to go.

When is the best time to take magnesium?

The best time to take magnesium depends on *why* you’re taking it. "In general, magnesium can be taken any time of the day," says John Beyer, MD, a psychiatrist at Duke Behavioral Health. Still, reasons for needing to take a magnesium supplement can vary, so read below to find the best time for you, depending on specific needs.

If you're taking magnesium for a deficiency

If this is the case for you, then taking magnesium any time of day should do just fine. Just make sure you do it with a lil food to prevent any stomach and gastro distress, explains Tambe.

If you're taking magnesium for sleep issues

This is where timing matters most. If this is the case for you, then it’s best to take magnesium before bed, says Tambe. FWIW, magnesium isn’t a legitimate sleep aid, like, say, a prescription sleeping pill, but taking it before bed (specifically magnesium glycinate!) has been said to help you relax and get some good quality Zzz’s. (Ahem, we know you've seen that viral TikTok magnesium-based "sleepy girl mocktail" all over your FYP.)

If you're taking magnesium for constipation

Magnesium oxide acts as a laxative and stool softener (!!) and is a popular magnesium formulation for constipation. That said, it's recommended to not take it at the end of the day on an empty stomach (because you'll be up all night with the sh*ts!!!). Since this form of magnesium will effect you anywhere from 30 minutes to a few hours, it's best to take when you have direct and uninterrupted bathroom access. If you’re taking a high dose of magnesium for constipation, researchers suggest dividing it into two to three doses throughout the day.

If you’re taking magnesium for migraines

A 2020 study found that taking magnesium each morning can help with these debilitating headaches, and the most important thing is taking it consistently. So find a time you can stick to and you'll be golden!

Magnesium 250 mg

Magnesium 250 mg

Magnesium with Ashwagandha 325mg

Advanced Magnesium Capsules

Magnesium Vegetarian Tablets 250mg

Magnesium 500mg

Magnesium Glycinate 100mg

Magnesium Bisglycinate

The best timing may also depend on whether you’re taking other supplements or medications, explains Mitzi de Maa, RD, LDN, a dietitian at Your Latina Nutrition. “Be aware of possible interactions with medications like antibiotics or diuretics," she says. "Always check with your healthcare provider about when to take magnesium for your safety.”

Does taking magnesium help with anxiety and depression?

According to a 2020 study in Nutrients, magnesium may also help with anxiety and depression, likely thanks to its benefits on sleep health and its role in regulating the body’s stress response. Plus, depression has been associated with lower magnesium levels, and supplementing with magnesium has been shown to improve depressive symptoms. However, there aren't any large-scale, randomized-control trials (the gold standard for research) evaluating this connection, explains Dr. Beyer.

"We do not understand the exact mechanism that magnesium uses to improve depression and anxiety, but we do know that in the brain magnesium is required for many of the neurotransmitters involved in mood regulation. It is also an essential part of our stress response system," says Dr. Beyer. That said, magnesium shouldn't be used as a first-line treatment for mental health, emphasizes Dr. Beyer, but it may be a helpful add-on to psychotherapy, medications, and lifestyle modifications.

If you want to add magnesium supplement in your current mental health medication routine, Dr. Beyer generally recommends 200 to 300mg per day, but it's always best to speak with your healthcare provider before starting a new supplement.

Gotcha. So how much magnesium should I take?

Most healthy women need a recommended 310 to 360mg of magnesium a day (this may differ depending on age and if someone is breastfeeding or not, JFYI!). But, there are specific instances where that number can change depending on, again, your specific reason for using the supplement. Oh, and keep in mind that these are recs for your total intake of magnesium—from both food and supplements combined. You shouldn't take more than 350mg per day of supplemental magnesium, per the NIH.

Sleep

A 2021 research review in the journal BMC Complementary Medicine and Therapies found insufficient evidence to recommend magnesium as an effective intervention for insomnia, but if you still want to try magnesium for sleep, Tambe recommends magnesium glycinate.

Constipation

Taking 250 to 1,000mg of magnesium oxide can be most effective for constipation, based on findings from a 2021 study in Nutrients. De Maa says you can also use magnesium citrate as a short-term treatment for constipation.

Migraines

The American Migraine Foundation (AMF) suggests taking 400 to 600mg of magnesium oxide since this blend is believed to help reduce pain and prevent blood vessels in the brain from narrowing (aka the science-y reason that causes migraines for some people). Taking magnesium oxide regularly could even help prevent those pesky PMS migraines, according to the AMF.

Mental health

A 2022 study in the journal Nutrients found that 250 to 500mg of magnesium helps improve depressive symptoms. De Maa says that magnesium glycinate or taurate are the most common forms for aiding in depression management.

Any dose of magnesium above 350 mg could be harder for a person’s body to tolerate, according to the NIH. Always consult your personal doctor, dietitian, or other medical professional before taking a new medication or supplement.

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