TL;DR: Not all magnesium is created equal. Magnesium chloride is significantly more water-soluble than magnesium sulfate (the compound in Epsom salt), which is why it's the form most topical magnesium products are built around — including our Nightly Reset lotion. Magnesium citrate and glycinate, by contrast, are oral-only forms you'll find in supplement capsules, not lotions. Here's the actual chemistry behind why the type of magnesium in your lotion matters, and what to look for on the label.
If you've gone down the magnesium rabbit hole for your family — Epsom salt baths, magnesium oil sprays, a bottle of magnesium citrate in the supplement drawer, and now a lotion — you've probably had the same thought we did before we started formulating: is this all the same mineral, just marketed five different ways?
It's a fair question, and it's one label reading doesn't always answer, because most brands just say "magnesium" without specifying which compound they're using. The form matters. It affects how well the product dissolves, how it feels on skin, and whether it's actually suited for topical use in the first place.
What's the Difference Between Magnesium Chloride and Magnesium Sulfate?
Magnesium chloride and magnesium sulfate are both magnesium salts, but they behave very differently once you try to put them in a lotion or a bath. Magnesium chloride is highly water-soluble — it dissolves at roughly 54 grams per 100 mL of water. Magnesium sulfate (the compound in Epsom salt) is far less soluble, at around 27 grams per 100 mL. That's about half.
Solubility isn't a minor technical detail. A more soluble salt dissociates more readily into free magnesium ions, which is the form magnesium needs to be in for a topical product to have any chance of interacting with the skin. This is the main reason magnesium chloride, rather than magnesium sulfate, has become the standard in topical magnesium oils, sprays, and lotions.
Why Does Kindred Naturals Use Magnesium Chloride in the Nightly Reset?
We formulated our Nightly Reset lotion with magnesium chloride specifically because of that solubility profile. It allows the magnesium to stay evenly dissolved and stable in the lotion base — paired with nourishing carriers like kokum butter — rather than settling out or feeling gritty on skin. It's also the form most commonly used in the research on topical magnesium application, which mattered to us as we developed the formula.
Why Does Solubility Matter for a Topical Product Specifically?
Skin is a good barrier — that's its job. For any mineral to have a chance of interacting with the skin's surface layers, it generally needs to be small, soluble, and evenly distributed across the area it's applied to. A magnesium compound that stays largely undissolved (like Epsom salt sitting at the bottom of a bathtub) has a harder time doing that than one that's fully dissolved into ionic form in a lotion.
This is also why you won't find magnesium sulfate marketed as a lotion ingredient the way you'll find it in bath salts. Sulfate's lower solubility works fine when you're soaking in a full tub of water for twenty minutes, but it's not practical for a leave-on skincare product meant to be massaged in and absorbed into a moisturizer base.
What About Magnesium Citrate or Glycinate — Why Aren't Those in Lotions?
If you've stocked magnesium citrate or magnesium glycinate in your supplement cabinet, you might wonder why those forms don't show up in skincare. The answer is straightforward: citrate and glycinate are bonded to organic acids and amino acids specifically to improve how they're absorbed through the digestive tract when swallowed. That bonding structure has nothing to do with skin — it's designed for oral bioavailability, not topical application.
In other words, citrate and glycinate are the right tools for a different job. They're excellent, well-studied forms for oral supplementation. They're just not formulated — or intended — for a lotion.
Is There Real Science Behind Magnesium Absorbing Through the Skin?
This is the question we get most often from research-minded parents, and we think it deserves an honest answer rather than a marketing one. Magnesium chloride's high solubility gives it a real, measurable advantage over less-soluble forms for topical use — that part of the chemistry is well established. What's still being actively researched is exactly how much magnesium crosses intact skin and reaches the bloodstream, and how that compares to oral intake.
A widely cited 2017 review in the journal Nutrients noted that while topical magnesium has real effects on the skin barrier and is well tolerated, the evidence that it meaningfully raises whole-body magnesium levels is still limited. That's why we frame the Nightly Reset as a lotion that may support relaxation and a calm bedtime routine as part of the sensory experience of application — the massage, the warmth, the ritual — rather than a treatment for a diagnosed magnesium deficiency. If you're concerned about a deficiency, that's a conversation for your pediatrician or doctor, not a lotion label.
What Should You Actually Look for on a Magnesium Lotion Label?
A few things worth checking before you buy:
The specific compound. "Magnesium" alone tells you nothing. Look for "magnesium chloride" listed in the ingredients, not just the word "magnesium" in the product name.
Where it falls in the ingredient list. Ingredients are listed by concentration. If magnesium chloride is buried near the bottom of a long list, it's likely present in a small amount.
What it's paired with. A well-formulated magnesium lotion should also nourish the skin barrier itself — carrier oils and butters that keep skin soft, not just a magnesium delivery vehicle with filler around it.
No synthetic fragrance stacked on top. A lotion meant for nightly use on a baby's or mom's skin shouldn't need synthetic fragrance to feel like a ritual. The scent (or lack of it) should come from what's actually in the formula.
Frequently Asked Questions
Is magnesium chloride the same as Epsom salt?
No. Epsom salt is magnesium sulfate. Magnesium chloride is a different, more water-soluble magnesium compound, which is why it's more commonly used in topical lotions and oils rather than bath salts.
Can magnesium lotion cause skin irritation?
Some people notice a mild tingling sensation with topical magnesium chloride, especially at higher concentrations or on skin with a compromised barrier. Formulating at a gentle concentration and pairing it with nourishing carriers, as we do in the Nightly Reset, helps minimize this. As with any new skincare product, we recommend a small patch test first, especially for babies.
Is topical magnesium safe to use on babies?
Our Nightly Reset lotion is formulated to be gentle enough for babies and adults alike, using a lower, family-friendly concentration of magnesium chloride. As always, introduce any new product gradually and check with your pediatrician if your child has particularly sensitive or reactive skin.
How is magnesium chloride sourced?
Magnesium chloride used in skincare is typically derived from natural mineral deposits or seawater, then purified for cosmetic use. It's a naturally occurring mineral salt, not a synthetic compound.
How often should you apply magnesium lotion?
Most families use it once nightly as part of a bedtime routine — applied to arms, legs, or feet after a bath. Consistency as part of a calming ritual tends to matter more than the amount used at any single application.
Understanding what's actually in your magnesium lotion — and why — means you're no longer taking a brand's word for it. You're reading the label the way it deserves to be read. If you're ready to see what a thoughtfully formulated, magnesium chloride–based lotion feels like for your family's bedtime routine, you can explore the Nightly Reset at shopkindrednaturals.com.
Written by Mike & Carly Pronsky, founders of Kindred Naturals.