Medical Terms

Onychomycosis – The medical term for nail fungus infections, derived from the Greek where Onycho means “pertaining to the nails” and mycosis means “a disease caused by a fungus”. It is estimated that approximately 6-10% of the adult population is affected – see prevalence studies below.

Tinea – A catch-all term for all fungal infections. When the infection affects the nail it is described as tinea unguium. “Unguium” is the Latin word for nails.

Ringworm – As with tine (above), this is another catch-all term of fungus infections. Ringworm of the nails describes fungal infections of the nails.

Dermatophyte – As explained in this article by the aafp, Dermatophyes are “fungi that require keratin for growth.” As we only have keratin protein (see next) in our skin, hair and nails, this is where the fungi are found.

Keratin – Keratin cells comprise the outermost layer of our skin, hair and nails.

Hyperkeratotic – An abnormal thickening of skin cells located in the outermost layer of the epidermis. The term “Hyperkeratotic debris” describes the overgrowth of dry flaky skin that can accumulate under the nails in people with Onychomycosis.

Trichophyton rubrum – A dermatophyte (see earlier) and one of the most common fungal organisms to infect the nails. Other dematophytes that can be involved with Onychomycosis include Trichophyton interdigitale, Epidermophyton floccosum, Trichophyton tonsurans and Microsporum gypseum.

Yeasts – Yeasts are single celled organisms and a type of fungus. The most commonly associated with infections that affect humans is Candida albicans. Candida spp. of yeast that can cause both Onychomycosis (specifically Candidal Onychomycosis – see below) as well as yeast infections.

Distal Lateral Sungungal Onychomycosis – The most common form, where the fungus invades from the free edge of the nail (the distal edge) and spreads towards the cuticle on the underside of the nail (refer to Nail Anatomy section below).

White Superficial Onychomycosis – The infection is more superficial in nature and forms white marks on the nail plate. It only accounts for around 1 in 10 of all fungus infections.

Proximal Subgungal Onychomycosis – Generally restricted to people who are immuno-compromised the fungus penetrates at the proximal end of the nail (near the cuticle).

Endonyx Onychomycosis – This occurs when the fungal organisms attack the nail plate but do not affect the nail bed.

Total Dystrophic Onychomycosis – Not really another form of Onychomycosis, this describes the total loss of the nail as a result of Onychomycosis and can be the end stage of the above forms of the disease. For more details read this medscape article on the progression and recurrence of Onychomycosis.

Candidal Onychomycosis – This form of the disease is the result of infection by Candida spp. rather than dermatophytes.

Undecylenic acid – Derived from castor oil, approved by FDA and used in popular nail fungus treatments such as Funginix (manufactured by The Sisquoc Healthcare Corporation) and Zetaclear (member of the Natural Products Association).

Tea Tree Oil – Derived from the plant Melaleuca alternifolia which is native to Australia. Tea Tree oil is often recommended as a companion treatment to other topical products and for prevention. It is often added as an ingredient to natural topical antifungal nail products.

Terbinafine – Marketed under the Brand names Lamisil (manufactured by Novartis Consumer Health) and Zabel, it is available as a topical cream against skin fungus infections or in oral form for the treatment of Onychomycosis.

Itraconazole – Often grouped together with other “azole” antifungals such as fluconazole or voriconazole, Intracomazole is a prescription anti fungal drug that is administered either orally or intravenously.

Griseofulvin – Administered orally for the treatment of skin and nail fungal infections.

Ciclopirox – This is a topical anti fungal medication, generally considered more effective when combined with oral medications. Ciclopirox is marketed under the brand name Penlac (manufactured by Sanofi.us)

Topical treatment – This refers to any medications that are applied externally to the affected nail(s).  See more on nail fungus treatment options.

Hepatotoxicity – A form of liver damage that is chemical induced. Studies have linked some oral drugs prescribed for Onychomycosis with increased risk of hepatotoxicity.

Leukonychia – White patches under the nail, most often caused by injury to the nail matrix. As nails grow slowly, there can be a long lag between he injury and the appearance of the white mark.

Onycholysis – A partial detachment or loosening of the fingernail or toenail from the nail bed.

Paronychia – An inflammation around the nail plate causing redness, swelling and pain. A pocket of puss can develop in severe cases. Paronychia can offer as a result of a material or fungal infection.

Onychia – Similar to paronychia (above) onychia describes the inflammation of the nail matrix and nail bed. Again this can result from fungal and bacterial infection.

Nail Anatomy Terms 

Distal edge of the nail – The free edge at the tip of the nail.

Lanula – the pale half moon shaped section at the back of the nail near the cuticle (see next)

Proximal fold – This is where the skin overlaps on itself at the base of the nail. The horney part of this is known as the cuticle (see next)

Cuticle or eponychium – This is an extension of the skin behind the nail.

Matrix – The matrix is located under the cuticle and is the place where new nail cells are formed, flattened and pushed forwards. It can be thought of as the nail growth center.

Subungal - This describes a position underneath the nail (the most common location of the fungus when it comes to Onychomycosis)

Nail plate – Made from hard layers of keratin this is a transparent structure that sits on the nail bed. The nail plate is continually being replaced by cells pushing forward from the nail matrix in a process that takes around 6 months for fingernails and 12-18 months for toenails.

Nail bed – This consists of shallow grooves and ridges that contain small blood vessels.

Hyponychium – This is where the nail plate detaches from the nail base at the tip of the nail. It is often where the fungus first invades.

Academic Reference Materials And Onychomycosis Prevalence Studies

A study by the International Journal Of Dermatology looking at the psychosocial implications of Onychomycosis. The potential of stigmatization and loss of quality of life is often ignored. The study demonstrates that the disease can have a negative impact on mental and social well-being.

Research by the Journal of European Academy Of Dermatology and Venererology focussed on identifying the different types of fungi that attack the nails.

Studies on prevalence rates of Onychomycosis carried out by:

• The British Journal Of Dermatology in Finland,
• In Spain, and
• By the US National Institute oF Health rates looking at Onychomycosis in Diabetic Neuropathic Patients.

Onychomycosis Diagnosis and Measurement – A collaborative study published by Pubmed.gov (part of the National Center for Biotechnology Information).