There are a number of skin conditions that can be a bit difficult to distinguish. A person who complains about itchy bumps on the scalp and assumes it is acne might actually be treating seborrheic dermatitis. Seborrheic dermatitis is a dandruff-like condition that can cause flaking and redness on the face as well as the scalp. Although there are probably somewhat different microbes associated with each condition, the results–itching, redness and flakes–are similar. Luckily, many of the same natural products can be used to control these problems.
Rosemary Oil for Scalp Acne:
Q. I’ve heard that rosemary oil in good for treating acne on the scalp. Is this true? I need an alternative to antibiotics.
A. Rosemary extract has been shown to possess both anti-inflammatory and anti-microbial activity. In particular, it can inhibit the inflammatory response skin cells mount as a reaction to the bacteria that cause acne (Tsai et al, Journal of Medicinal Food, April, 2013). The rosmarinic acid in rosemary oil suppresses IL-8, a type of interleukin produced in response to Propionibacterium acnes.
Lauric acid, a component of coconut oil, appears to suppress the growth of P. acnes on the skin (Nakatsuji et al, Journal of Investigative Dermatology, Oct. 2009). This would suggest that infusing coconut oil with rosemary and applying it to the scalp prior to shampooing might be one approach for controlling scalp acne.
Other herbal extracts may be useful for treating seborrheic dermatitis or other causes of itchy scalp. Many readers have sent testimonials on the benefits of Listerine:
Soothing Your Itchy Scalp:
Q. Using old-fashioned amber Listerine for my itchy scalp worked wonders. Thank you for writing about this remedy.
Is It Infectious Dandruff?
A. The original maker of Listerine used to advertise its product for “infectious dandruff.” This had certain advantages from the perspective of the advertiser, since it fed social paranoia and made people even more anxious to get rid of (or cover up) their itchy flakes. But there’s no good evidence that dandruff is actually contagious or infectious.
That is probably why the FDA no longer allows this claim for Listerine. Nonetheless, dandruff and seborrheic dermatitis are characterized by flaking, redness and itching of the skin on the scalp or even on the face. Some people do seem to do well treating seborrheic dermatitis with this product.
The Mysteries of Malassezia:
Both conditions are associated with an overabundance of normal skin yeast called Malassezia globosa (Hay, British Journal of Dermatology, Oct., 2011). This yeast requires fat to grow, so human skin provides excellent conditions for it. In fact, children start with a much wider range of skin fungi or yeast, but after puberty Malassezia globosa appears to dominate (Jo et al, Journal of Investigative Dermatology, Dec. 2016). In addition to seborrheic dermatitis, Malassezia can cause a skin discoloration called tinea versicolor. Overgrowth with Malassezia is linked to skin itching and flaking.
Listerine to the Rescue:
While many dandruff shampoos can knock down Malassezia populations on the skin, the ingredients in Listerine also have antifungal activity. Veterinary researchers in Tehran isolated several Malassezia species (including M. globosa) from dogs with itchy skin (atopic dermatitis). They cultured the yeast and applied medicinal essential oils to see which were most helpful against these skin denizens. The most effective of these were Zataria multiflora, a wild herb from Iran that contains thymol and carvacrol, and Thymus kotschyanus, an Iranian species of thyme (Khosravi et al, Journal de Mycologie Medicale, March, 2016).
Thymol is an important constituent of both plants and an active ingredient in Listerine. It is reasonable to conclude that the thymol in Listerine contributes to its activity against common Malassezia.
Many people report that thoroughly soaking the scalp with Listerine before shampooing can control dandruff. Others have found that rinsing the scalp with amber Listerine after washing the hair relieves itching and flaking.
Our Guide to Hair and Nail Care includes a discussion of Listerine and many other home remedies for dandruff.