Milk of magnesia is a time-honored medicine to treat constipation. But that is not the only use for this versatile compound. We first heard about using milk of magnesia in the armpits to suppress odor about a dozen years ago:
Q. I want to share a remedy I learned about when traveling in Brazil. Just apply milk of magnesia to your armpits. It is the best underarm deodorant!
A. What an unusual idea. Milk of magnesia contains magnesium hydroxide, which is both an antacid and a laxative. We have never heard of applying it to underarms, though. Perhaps it reduces the acidity of the skin to make odor-forming bacteria less welcome.
Dual Uses for Magnesium:
Q. I have followed your advice about the benefits of magnesium, both as a dietary supplement and using topical milk of magnesia as a deodorant. This has worked very well, but lately I’m experiencing loose stools.
I stopped the 250 mg supplement while continuing to apply milk of magnesia under my arms. The stool issue hasn’t abated. The question now is: can the topical application of milk of magnesia every other day, alone, produce over-absorption of magnesium and the lack of firm stools?
Do You Absorb Magnesium from Your Armpits?
A. Scientists are not convinced that magnesium can be absorbed well through the skin (Grober et al, Nutrients, Aug. 2017). That said, you might want to discontinue using milk of magnesia as a deodorant for a couple of weeks to see whether your loose stools resolve. Some people appear more sensitive to the laxative effect of magnesium than others.
What Are the Benefits of Magnesium?
Constipation:
As already mentioned, magnesium is an excellent remedy to overcome constipation. People who plan to use magnesium for regularity must have good kidney function, though. Otherwise, blood levels of this mineral could build up to toxic levels.
Insomnia:
Many people have found that magnesium supplements in the evening help them get to sleep more easily. There are, unfortunately, few published studies to support or refute this idea. Researchers have reported that magnesium supplements can help older people with insomnia (Abbasi et al, Journal of Research in Medical Sciences, Dec 2012). Despite previous reports, Israeli investigators have found that magnesium oxide supplements did not prevent nighttime leg cramps (Rouguin Maor et al, JAMA Internal Medicine, May 1, 2017).
Headaches:
Some people who get recurrent migraine headaches find that magnesium supplements help prevent them. They are among a handful of nutraceuticals that show promise for this purpose (Rajapakse & Pringsheim, Headache, Apr. 2016; Daniel & Mauskop, Current Treatment Options in Neurology, Apr. 2016; D’Onofrio et al, Neurological Sciences, May 2017).
Stroke Prevention:
People who eat foods rich in the mineral magnesium appear to be less likely to suffer strokes. That is the conclusion of a meta-analysis involving roughly 240,000 people (Larsson et al, American Journal of Clinical Nutrition, Feb. 2012). Foods rich in magnesium include halibut, almonds, cashews, soybeans, spinach, and other dark green leafy vegetables as well as legumes like black-eyed peas and lentils. (Find a list here.) The more magnesium-rich foods people consumed, the lower their risk of experiencing a blood clot in the brain.
A more recent epidemiological study confirms this association (Adebamowo et al, International Journal of Stroke, Oct. 2015). Based on data from the Health Professionals Follow-Up Study, the researchers concluded that men who get the most magnesium, potassium and calcium from their diets lower their chances of a stroke by more than 20 percent (relative risk). They also found that women who eat foods rich in potassium and magnesium lower their risk of stroke (Adebamowo et al, American Journal of Clinical Nutrition, June 2015).
Seborrheic Dermatitis:
A number of readers praise milk of magnesia as a topical treatment for rosacea. Others apply it to eczema and rashes. In addition, some people laud its benefits for seborrehic dermatitis, a type of dandruff of the face:
Q. You recently had an article about treating seborrheic dermatitis with milk of magnesia. My mom is wondering how much milk of magnesia she should take.
A. Please tell your mother NOT to swallow milk of magnesia (MoM) for her skin problem. This is a powerful laxative and if she consumes too much, she will be dashing for the bathroom.
Instead, suggest that she apply MoM to the itchy, flaky, red areas of her skin. For reasons that are not clear to us, this remedy seems to help both acne and seborrheic dermatitis.
There don’t seem to be any studies of milk of magnesia for seborrheic dermatitis, but one group of investigators established that a 2 percent magnesium cream speeds recovery from diaper rash (Nourbakhsh et al, Journal of Clinical and Diagnostic Research, Jan. 2016).
Body Odor:
As we have already mentioned, magnesium in the form of milk of magnesia has become a popular way to control body odor. Many people find it less irritating than standard antiperspirants. Others are happy to avoid the aluminum salts that are the active ingredients in all American antiperspirants. We heard from one reader that her family in Cuba often used milk of magnesia in their armpits to keep from smelling bad. Apparently, this remedy goes back at least 60 years.
