Patient Presentation
A 15-year-old male came to clinic with a history of 2 days of increased pain and drainage around his right great toe after tearing part of the nail off. He had soaked his foot a couple of times but still had yellow drainage, redness, and pain. He was otherwise well and had no specific medical problems.

The pertinent physical exam showed a well appearing male with normal vital signs and growth. The medial nailfold of the right great toe was reddened with some accumulation of pus under the skin. There was some crusted material on the nail itself consistent with dried secretions. The nailfold was very tender to touch, but the rest of the toe was normal and there was full range of motion in the toe and foot structures. There did not appear to have a distinct ingrown toenail.

The diagnosis of a paronychia was made. The pediatrician cleaned and prepped the area with iodine, and gently retracted the nailfold away from the nail, expressing pus that was cultured. The patient was given an antibiotic prescription and encouraged to continue to do soaking of the foot to soften the nail bed and do gentle retraction of the nailfold to allow any accumulated secretions to drain. “Should we put Epsom salts into the water?” the mother inquired. “I don’t know that it will help, but usually it won’t hurt. I’d stay away from any scented salts though and just use plain ones. That way it’s less likely to irritate the toe. You can soak for 10-15 minutes.” he explained. He also gave wound care instructions and how to appropriately cut toenails in the future.

Discussion
Epsom salt is magnesium sulfate. It is named Epsom from the town in England, close to London where it was supposedly discovered.
Magnesium is an important trace element. It is a co-factor for ATP metabolism, DNA and RNA synthesis and regulation, and multiple other enzymatic reactions.

Hypermagnesemia is quite uncommon and usually would occur because of renal insufficiency or being iatrogenically produced. Hypomagnesemia is a serum concentration of < 0.75 mmol/L. Symptoms are often non-specific such as lethargy, anxiety, headache, decreased appetite, nausea and sleeping problems. Muscle spasms and muscle associated pain can occur. Arrhythmias and central nervous system problems including seizures can occur. Hypomagnesemia can frequently co-occur with other electrolyte abnormalities such as hypocalcemia or hypokalemia.

Magnesium is commonly used to treat cardiac problems such as cardiac failure and arrhythmias, eclampsia and pre-eclampsia. It can also be used as a secondary treatment for severe asthma, temporizing treatment for digoxin toxicity, and as an anticonvulsant if appropriate. It can be used for patients with hypomagnesemia due to malnutrition as well. Magnesium is given orally or intravenously usually to treat these and other conditions.

The skin is the largest organ and is designed as the barrier to the outside world. A transdermal substance has to pass through the epidermis and the stratum corneum which specifically are designed to negate such passage. Basically, magnesium cannot pass transdermally through intact skin but it may be possible to be absorbed around the hair follicles and sweat glands.

A review of paronychias can be found here.

Learning Point
In the lay public, Epsom salt is used as a bath for a variety of conditions including muscle and joint pain, bruises and sprains, soothing mildly irritated skin, sleep and stress, and paronychia. There are few good research studies that support topical magnesium sulfate use, but it also does not generally cause problems. Severely irritated skin or open wounds should not be treated with Epsom salt baths and obviously Epsom salts should not be ingested orally. There potentially could be a placebo affect and/or the bathing activity itself (needing to stop and rest in a usually relaxing environment) could also provide benefits to the individual. Additionally, sometimes Epsom salt also may have scents added which are designed to be pleasing and add to the bathing experience. Per the Epsom Salt Council, it can also be used in cosmetics, crafting and gardening. The author could not find any references to Epsom salt or magnesium at the websites for the American Academy of Dermatology, the National Institute of Complementary and Integrative Health, or MedLinePlus. MedLinePlus does have a magnesium factsheet available here.

There are a few good studies which support topical magnesium. For example two studies found improved atopic dermatitis symptoms but the treatment was not magnesium monotherapy and other components of the treatment could be significant factors. There are other studies which show improvement in a variety of patients after bathing in the Dead-Sea or with simulated bath-salt solutions. Many of these are not controlled, have few numbers of patients and/or not published in scientific journals.

Questions for Further Discussion
1. What are the risks of amber teething necklaces which are used by some for pain relief? A review can be found here
2. What types of molecules penetrate the skin better?
3. What conditions help molecules penetrate the skin better?

Related Cases

Disease: Paronychia | Foot Injuries and Disorders | Magnesium | Minerals

Symptom/Presentation: Infections | Foot Pain

Specialty: Dermatology

Age: Teenager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Foot Injuries and Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Kaye P, O’Sullivan I. The role of magnesium in the emergency department. Emerg Med J. 2002;19(4):288-291. doi:10.1136/emj.19.4.288

Chandrasekaran NC, Sanchez WY, Mohammed YH, Grice JE, Roberts MS, Barnard RT. Permeation of topically applied Magnesium ions through human skin is facilitated by hair follicles. Magnesium research. 2016;29(2). doi:10.1684/mrh.2016.0402

Grober U, Werner T, Vormann J, Kisters K. Myth or Reality-Transdermal Magnesium? Nutrients. 2017;9(8):813. doi:10.3390/nu9080813

Maarouf M, Vaughn AR, Shi VY. Topical micronutrients in atopic dermatitis – An evidence-based review. Dermatologic Therapy. 2018;31(5):e12659. doi:10.1111/dth.12659

Saeg F, Orazi R, Bowers GM, Janis JE. Evidence-Based Nutritional Interventions in Wound Care. Plast Reconstr Surg. 2021;148(1):226-238. doi:10.1097/PRS.0000000000008061

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa