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Can Milk of Magnesia Applied Topically Help with Acne?

There Is No Scientific Evidence That Over-the-counter Milk of Magnesia Products Would Help

By: Dan Kern, Acne.org Founder & CSO
Last updated: February 06, 2020

The Essential Information

Milk of magnesia is an oral remedy for treating heartburn and stomach ailments that is sold at just about any drugstore.

Some acne sufferers try applying milk of magnesia to the skin topically in the hope that this will improve acne. However, no scientific evidence to date shows any potential benefit of applying over-the-counter milk of magnesia products to acne.

The Bottom Line: The vast majority of home remedies show little promise in acne treatment, but even among this unimpressive group, milk of magnesia stands out as unremarkable. It's probably best to save your milk of magnesia for when you get heartburn or upset stomach.

The Science

Milk of magnesia is an over-the-counter oral medication for relieving indigestion, constipation, heartburn, and upset stomach. Although milk of magnesia is only sold for oral use, some people with acne apply it topically in an attempt to treat acne breakouts and improve the appearance of acne scars. However, there is currently no scientific evidence that regular milk of magnesia has any effect on acne.

What Is Milk of Magnesia?

Milk of magnesia is a milky-looking liquid consisting of a white solid called magnesium hydroxide suspended in water.

milk of magnesia magnesium hydroxide suspended in water

What Is Milk of Magnesia Used For?

Milk of magnesia is approved for oral use as a(n):

  • Antacid: Treats symptoms caused by too much stomach acid, such as heartburn, upset stomach, or indigestion
  • Laxative: Relieves constipation1

Does Milk of Magnesia Work Topically for Acne?

To date, no studies have tested milk of magnesia as a topical treatment for acne, but could milk of magnesia be beneficial even though researchers have not tested it? To be effective against acne, milk of magnesia would need to possess at least one of the following medicinal properties:

  • Antibacterial activity: An ability to kill bacteria like P. acnes, a type of bacteria that plays a role in the development of red and sore acne lesions
  • Anti-inflammatory activity: An ability to reduce redness, itching, swelling, and soreness, all of which are hallmarks of acne breakouts
  • Antioxidant activity: An ability to remove free radicals, which are naturally occurring toxins that can build up in the body and contribute to acne
  • Wound-healing properties: An ability to speed up the healing of wounds in the skin. Acne lesions, scientifically speaking, are small wounds.2

There is no evidence that milk of magnesia in the form currently available on the market possesses any of these acne-fighting properties.

milk of magnesia medicinal properties

In most cases, scientists simply haven't tested milk of magnesia to see whether it possesses these medicinal properties, aside from one test that showed that nanoparticles of milk of magnesia can kill some types of bacteria. However, over-the-counter milk of magnesia doesn't use nanoparticles. Regardless, let's take a quick look at that research.

The research on milk of magnesia and antibacterial activity

Scientists have tested the ability of nanoparticles of magnesium hydroxide, which are extremely tiny particles of the same substance found in milk of magnesia, to fight bacteria. They found that nanoparticles of milk of magnesia can kill some types of bacteria.3,4 Unfortunately, the researchers did not test the nanoparticles on the type of bacteria that makes acne worse, called P. acnes. It is also important to note that milk of magnesia currently on the market consists of much larger particles, not nanoparticles. In other words, the results of this study do not change the fact that milk of magnesia currently found on the market has no proven antibacterial activity.

Expand to read details of study

Materials Letters

The study was published in 2014 in the journal Materials Letters. The researchers found that nanoparticles of milk of magnesia kill some types of bacteria, probably by entering the bacteria cells and destroying them from the inside. The researchers wrote, " we found that [magnesium hydroxide] nanoparticles were effective antibacterial agents against several bacteria."3

milk of magnesia antibacterial effect

Bacteria in a petri dish before (left) and 24 hours after (right) the addition of magnesium hydroxide nanoparticles. After 24 hours, magnesium hydroxide has killed the bacteria. Note: This bacteria is not acne bacteria.3

Side Effects of Milk of Magnesia Applied Topically

Because the research on applying milk of magnesia topically is very limited, we cannot say whether milk of magnesia is safe for topical use. However, patient reports suggest that topically applied milk of magnesia might cause skin irritation.

The Bottom Line

In conclusion, we have no evidence to date that milk of magnesia applied topically has any effect on acne. It is possible that future research may find some benefit to applying milk of magnesia to acne-prone skin. However, currently we cannot recommend this as a home treatment for acne.


  1. Magnesium hydroxide, https://en.wikipedia.org/wiki/Magnesium_hydroxide
  2. Oberemok, S. S. & Shalita, A. R. Acne vulgaris, I: pathogenesis and diagnosis. Cutis 70, 101 - 105 (2002). https://www.ncbi.nlm.nih.gov/pubmed/12234155
  3. Dong, C. et al. Study on antibacterial mechanism of Mg(OH)2 nanoparticles. Mater Lett 134, 286 - 289 (2014). https://www.sciencedirect.com/science/article/abs/pii/S0167577X1401369X
  4. Dong, C. et al. Antibacterial study of Mg(OH)2 nanoplatelets. Mater Res Bull 46, 576 - 582 (2011). https://www.researchgate.net/publication/251484730_Antibacterial_study_of_MgOH_2_nanoplatelets

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