Fungal Skin Infections
Fungal skin infections involving a group of fungi known as dermatophytes are one of the most common infections in humans worldwide. Other frequent causes of fungal skin infections include Candida albicans and Malassezia furfur (White 2014).
Note : this section focuses on fungal infections of the skin; more general information about fungal infections, including systemic candidiasis, is available in the Fungal Infections (Candida) protocol.
This very common condition includes a set of superficial infections of the skin, hair, and nails caused primarily by three groups of fungi known as dermatophytes: Trichophyton, Microsporum, and Epidermophyton. Tinea corporis (ringworm), tinea pedis (athlete’s foot), and tinea cruris (jock itch) are examples of dermatophytoses (Cevasco 2010; Sahoo 2016).
Cutaneous candidiasis is an infection of the skin and/or nails by Candida albicans or other Candida species. It is most common in individuals treated with antibiotics, diabetics, immunocompromised patients, and those with other skin afflictions (Aaron 2015; Cevasco 2010).
Tinea (or pityriasis) versicolor
Tinea versicolor, also known as pityriasis versicolor, is a fungal infection affecting skin pigmentation and involving species of the fungus Malassezia, such as Malassezia furfur.It is more common in hot, humid climates and may be associated with oral contraceptives, oral corticosteroids, immunosuppression, and malnutrition. The characteristic patches seen in tinea versicolor are either hypopigmented (white) or hyperpigmented (pink, tan, brown, or black) (Cevasco 2010; White 2014).
Onychomycosis (nail fungus)
Fungal infections of the toenails or fingernails are quite common, affecting about 10% of the general US population, with toenail infections being more prevalent than fingernail infections. In addition to disfiguring the nail(s), onychomycosis may cause pain and interfere with physical activity. The most common causative organism in onychomycosis isTrichophyton rubrum; other causal organisms include Trichophyton mentagrophytes and Epidermophyton floccosum. Ninety percent of toenail fungal infections involve dermatophytes. Treatment may involve topical and/or systemic antifungal medications, depending on the extent and location of the infection. Importantly, in nearly half of cases abnormal nail appearance is not due to fungal infection, so seeing a doctor for testing to identify the causal agent is fundamental to treatment planning (Bodman 2017; Westerberg 2013). More detailed information about onychomycosis is available in the Nail Disorders protocol.
Conventional Treatment of Fungal Skin Infections
Topical antifungal agents are generally effective against certain common fungal infections (Sahoo 2016). Common examples of medications in this class include ketoconazole and econazole. In cases of more extensive fungal skin infections, oral antifungal drugs may be prescribed; these may include oral ketoconazole or oral micronized griseofulvin (Cevasco 2010). More care is needed with oral antifungal drugs because several may cause side effects or interact with other drugs. It is important to note that, like pathogenic bacteria, dermatophytes are becoming increasingly resistant to conventional treatments. Much attention has, as a result, been focused on natural products with antifungal properties for treating fungal skin infections (Lopes 2017).
For onychomycosis, topical treatment options include ciclopirox olamine 8% and efinaconazole 10% solutions. Often, topical treatments alone are not sufficient to eradicate the underlying infectious agent and cure the nail infection, so systemic medication is frequently indicated. Oral antifungal agents that may be used to treat onychomycosis include itraconazole (Sporanox) and terbinafine (Lamisil) (Kreijkamp-Kaspers 2017). The cure rates for systemic medications range from about 50% to about 75%. Side effects of oral antifungal agents used to treat onychomycosis include flu-like symptoms, gastrointestinal distress, infections, headaches, elevation of liver enzymes, and altered metabolism of other drugs (Bodman 2017; Westerberg 2013; Kreijkamp-Kaspers 2017).
Integrative Treatment of Fungal Skin Infections
In a four-week controlled trial, a topically applied powder made with 20% zinc undecylenate and 2% undecylenic acid improved symptoms and reduced the presence of fungi in patients with tinea pedis (athlete’s foot) (Chretien 1980). Topical 1% zinc pyrithione solutions are often used successfully to treat tinea versicolor, and a 15% topical zinc sulfate solution has also shown promise for this condition (Gupta 2014). Preparations of zinc oxide nanoparticles have demonstrated activity against Candida albicans (Khan 2014; Mohandas 2015).
Garlic and its active constituents have antifungal effects against certain dermatophytes (Aala 2014), and have been effective against a variety of skin pathologies in early research (Pazyar 2011). In a pilot trial, a cream with 0.4% ajoene, a sulfur-containing compound from garlic, led to complete resolution of tinea pedis in 27 of 34 (79%) study participants after seven days, and in all participants after 14 days (Ledezma 1996). In another trial, 1% ajoene cream was as effective as the antifungal medication terbinafine in treating tinea pedis (Ledezma 2000). An animal model of a fungal infection showed that garlic consumption enhanced the immune response to the fungal pathogen in infected mice (Burian 2017). In an in vitro study, the garlic constituent allicin inhibited the growth of the common dermatophyte Trichophyton rubrum, which can infect the skin (Aala 2014).
Essential oils from plants such as tea tree, eucalyptus, juniper, cedar, and lavender have a long history of use as topical treatments for fungal skin and nail infections. Laboratory studies have shown that various essential oils, their constituents, and combinations of essential oils have strong antifungal properties against common dermatophytes and Candida species (Baptista 2015; Takao 2012; Zuzarte 2012; Cavaleiro 2006). Findings from one such study suggest the addition of salt could increase the anti-dermatophyte activity of essential oils combined in a hot water bath (Inouye 2007). Experimental evidence also suggests essential oil constituents may enhance the activity of the antifungal medication fluconazole (Diflucan) against drug-resistant fungal strains (Khan 2011). Topical essential oils have been found to be helpful in sheep and horses affected by tinea corporis (ringworm) (Pisseri 2009; Mugnaini 2013).
Clinical trials show that topical tea tree oil can combat fungal infections (Martin 2004). In one trial, 25% and 50% tea tree oil preparations were more effective than placebo in patients with tinea pedis (athlete’s foot), but caused temporary skin irritation in some participants (Satchell 2002b). Topical tea tree oil was found in another trial to be as effective as the topical antifungal medication clotrimazole 1% (Lotrimin) in patients with fungal nail infections after six months of twice-daily treatment (Buck 1994).