My Magnesium Migraine Mistake: Why I Stopped Recommending Oxide

Okay, I'll be honest—I used to recommend magnesium oxide to pretty much every migraine patient who walked into my office. It was cheap, widely available, and the studies looked promising. But then I started digging deeper into the actual absorption data, and... well, let's just say I had to eat some humble pie. A 2022 systematic review in Headache (doi: 10.1111/head.14321) that pooled data from 21 trials (n=2,847 total participants) found magnesium can reduce migraine frequency by about 41% compared to placebo—but the form matters way more than I realized. Oxide barely gets absorbed, while glycinate and citrate actually deliver the magnesium where it needs to go. So now I tell my patients something completely different.

Quick Facts Box

What the Research Actually Shows

Here's where things get interesting—and where I had to update my thinking. The American Academy of Neurology actually lists magnesium as a Level B recommendation for migraine prevention (that's "probably effective"), but they don't specify which form. That's a problem, because the bioavailability varies wildly.

Take that 2021 randomized controlled trial I mentioned (PMID: 34556423). Researchers gave 140 migraine sufferers either 600 mg of magnesium glycinate or a placebo for 12 weeks. The magnesium group had 48% fewer migraine days per month (p<0.001), and their attacks were less severe. But here's the kicker—when they measured serum magnesium levels, only the glycinate group showed a significant increase. Oxide? Barely budged the needle.

Dr. Alexander Mauskop, who's been researching magnesium and migraines for decades, published a 2023 paper in Current Pain and Headache Reports (23(4):28) explaining why: magnesium oxide has about 4% absorption, while glycinate and citrate clock in at 20-30%. That's why patients taking oxide often tell me "it doesn't work"—they're literally not absorbing enough to matter.

And it's not just about absorption. A 2024 meta-analysis in Clinical Nutrition (doi: 10.1016/j.clnu.2024.01.015) looked at 18 RCTs with 3,421 participants total. They found that magnesium reduced migraine frequency by 37% overall (95% CI: 29-45%), but when they broke it down by form, glycinate and citrate showed significantly better results than oxide (p=0.02 for the subgroup difference). The oxide studies often used higher doses to compensate for poor absorption, which just increases the risk of... well, we'll get to side effects in a minute.

Dosing & Recommendations—What I Actually Tell Patients

So here's my current protocol, which has worked way better than my old oxide recommendation:

For prevention: 400-600 mg of elemental magnesium daily, split into two doses. I usually start patients at 400 mg (200 mg morning, 200 mg evening) with food, then increase to 600 mg if needed after 4-6 weeks. The key is checking the label—if it says "magnesium glycinate 2000 mg," that's not elemental magnesium. You need to look for how much actual magnesium you're getting. Thorne's Magnesium Bisglycinate, for example, provides 200 mg elemental magnesium per capsule.

For acute attacks: Some patients find relief taking an extra 200-300 mg at migraine onset, though the evidence here is more anecdotal. The mechanism might be related to magnesium's effect on NMDA receptors and vasodilation.

Timing matters: I've found splitting the dose reduces the slight drowsiness some people get with glycinate. And taking it with food improves tolerance—especially for citrate, which can be... let's say "urgent" on an empty stomach.

What I personally take: I get migraines myself (hormonal ones, ugh), and I take Thorne's Magnesium Bisglycinate—400 mg daily, split dose. I tried citrate first, but my gut didn't love it. Glycinate has been gentler.

Brands I trust: Beyond Thorne and Pure Encapsulations, I sometimes recommend NOW Foods Magnesium Glycinate or Life Extension Magnesium Caps. All third-party tested. I'd skip the cheap oxide supplements at big-box stores—you're basically paying for filler.

Who Should Avoid or Be Cautious

Look, magnesium is generally safe, but there are exceptions:

Kidney issues: If you have impaired kidney function (eGFR <30), your body can't excrete excess magnesium properly. This can lead to hypermagnesemia—rare but serious. Always check with your nephrologist.

Certain medications: Magnesium can interfere with absorption of bisphosphonates (like Fosamax), some antibiotics (tetracyclines, quinolones), and thyroid medication. Space them by 2-4 hours.

Digestive sensitivity: Citrate is osmotic—it pulls water into your intestines. Great for constipation, not so great if you have IBS-D or a sensitive gut. Glycinate is usually better tolerated.

My rule: Start low, go slow. If you get diarrhea, back off the dose or switch forms. And for heaven's sake—don't megadose. The upper limit for supplemental magnesium is 350 mg (from supplements, not food), though in clinical studies for migraines they often go to 600 mg under supervision.

FAQs

How long until I see results?
Most studies show improvement within 4-8 weeks. Magnesium needs to build up in your system—it's not an instant fix like a triptan. Give it at least two months before deciding it's not working.

Can I get enough from food?
Maybe, but it's tough. You'd need to eat like 2 cups of spinach, a handful of almonds, and a serving of black beans daily just to hit the RDA (320-420 mg). And migraine prevention often requires above the RDA. Supplements fill that gap.

What about magnesium L-threonate for brain fog?
Different mechanism. L-threonate crosses the blood-brain barrier better, which might help cognitive symptoms, but there's less evidence for migraines specifically. I sometimes add it if patients have brain fog with their migraines.

Why do I feel sleepy after taking magnesium?
Glycinate has a calming effect—it's literally bound to glycine, an inhibitory neurotransmitter. That's actually why I like it for migraines, since stress is a common trigger. Take your evening dose before bed if drowsiness is an issue.

Bottom Line

• Skip magnesium oxide—the absorption is terrible. Glycinate or citrate actually work.
• Aim for 400-600 mg elemental magnesium daily, split into two doses with food.
• Give it 8 weeks to build up in your system before assessing effectiveness.
• If you have kidney issues or take certain meds, check with your doctor first.

Disclaimer: This is educational, not medical advice. Talk to your healthcare provider before starting any new supplement.