You always hear beauty gurus say that Milk of Magnesia (MOM), an OTC antacid and laxative, can secretly double as a life-saving foundation primer or mask for those with oily skin types. But does using Milk of Magnesia actually work to absorbing facial oil? And are there any drawbacks to this off-label use?
In its unflavored and most widely-used form, magnesium hydroxide (Mg(OH)2) is the active ingredient, accompanied by water and sodium hypochlorite (NaClO) (1).
Mg(OH)2 acts as an antacid (to counter something like stomach ulcers) via neutralization: Mg(OH)2 will dissociate in water, and the basic hydroxide ions (OH-) will combine with the acidic hydrogen ions (H+) in stomach acid to form water. Hence, neutralization.
As a laxative, Mg(OH)2 relies on the magnesium ions (Mg2+) that form upon dissociation. Because these ions aren’t largely absorbed by the intestinal tract, they will draw water from the surrounding tissues, which will increase the water content of the intestinal tract, resulting in softer and more “passable” fecal matter. Mg2+ ions also cause the release of a compound called cholecystokinin, which similarly results in higher levels of water, electrolytes, and intestinal movement (2).
The other ingredient of importance is sodium hypochlorite (NaClO), otherwise known as bleach. It is in very low concentration and acts as a pH adjuster or buffer. When dissolved in water, NaClO will slowly decompose, releasing chlorine, oxygen and sodium hydroxide.
The reaction of this process is: 4 NaClO + 2 H2O → 4 NaOH +2 *Cl2 +O2.
*Keep in mind that the rate of decomposition is extremely slow, so the amount of chlorine gas emitted will probably be negligent. However, it’s best to not inhale bleach for any sustained periods of time.
Milk of magnesia does indeed has some ability to absorb surface lipids on the skin. Though not many studies have been specifically designed to test this concept, one study suggests that Mg(OH)2 works better than magnesia or magnesium oxide (MgO) at facilitating the absorption and separation of wax and stearyl esters, which are similar to compounds found in sebum (3). While this is far from conclusive, it does give some weight to the efficacy of MOM as a “degreaser.”
Furthermore, what little of the bleach content is present, can further “degrease” the skin. As a strong oxidizer, bleach can cause defatting or the chemical dissolution of surface lipids (4), resulting in less oil on the skin.
Clearly, the most obvious drawback is that Milk of Magnesia is quite alkaline — as are its two main ingredients magnesium hydroxide (Mg(OH)2) and sodium hypochlorite (NaClO). MOM has an overall pH of 10.5, while sodium hydroxide (NaOH), as seen above in the chemical reaction has an astonishingly high pH of 14 (5)!
When the skin is at a basic pH, all kinds of problems related to impaired skin can manifest, such as contact dermatitis, increased acne (since a basic pH interferes with regular desquamation and allows for bacteria proliferation), and many others. That's because Milk of Magnesia disrupts the acid mantal that helps to serve as a protective barrier.
With consistent use, MOM can seriously wreck your skin!
Relax. If you’ve been applying MOM to the skin, just discontinue use. If you’re bummed out because something so promising isn’t actually so, don’t worry! There are other (better) ways to deal with oily skin, ranging from something as complicated as oral isotretinoin, to something as simple as a pressed powder. There are too many to identify, describe, and analyze! Therefore, keeping in line with this post, here are a few topical “cosmetic” absorbents that can easily replace MOM:
Ultimately, my personal Holy Grail product is the Hourglass Mineral Veil Primer because it really extends the wear-time of anything I apply over it by a few hours. It also provides decent UVA and UVB protection, which coupled with its silky, water-light texture, makes it a perfect mixing medium for my regular sunscreen.
Milk of Magnesia does have some ingredients that allow it to absorb oil in the short term. However, it's very, very akaline, which is a big no-no in skin care. Alkaline products can damage skin after just one use. And the damage is cumulative; keep using it and it will get worse. Instead, try some foundations formulated specifically to help oily skin.
Have YOU tried MOM before? Let me know what you think in the comments!
About the author: John Su is an established skin care expert and aspiring dermatologist. He also runs a blog, The Triple Helix Liaison, dedicated to providing unbiased, meaningful, and insightful information about skin care.
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