Why are my toenails yellow?

It is often said that the eyes are the window to the soul and the nails are the window to health, indeed the father of modern medicine Hippocrates accurately used the nails of patients to diagnose disease 2500 years ago (1). It is true that many illnesses manifest through the nails, such as the common permanent deep ridges in the nails known as “Beau’s lines” that form after a recent bout of a simple cold or flu. At Carlisle Foot Clinic the most common nail complaint we see is yellowing of the nails.

Yellow nails can have a number of causes, but the most common is Onychomycosis. Onychomycosis is a fungal infection of the toenails that causes yellow discoloration, thickening, and permanent separation of the nail from the nail bed. The infection typically starts in the skin of the feet, transferred from another person in communal walking areas within gym and pool changing facilities, spas, yoga studios, nail salons/bars, martial art studios or a persons own home. The infection in the skin is typically dry but may also cause a lot of wetness between toes and a distinct odour. Onychomycosis occurs in 10% of the general population (2) and has reportedly included some of the world’s best known celebrities including Kate Moss, Robert Pattinson and Madonna (3). Yellow nails not only cause psychological distress and reduce self-esteem but creates difficulties walking, exercising, and finding suitable shoes, therefore everyone should follow some simple steps to reduce catching the offending fungus:

1. Treat athletes’ foot early – the most common route of infection of the nails is by the skin, simple treatment of athletes foot at the first signs will stop the fungus reaching the toes.

2. Psoriasis – If you or a family member have psoriasis this can cause your nails to be brittle and crack allowing the fungus to get into the nail, a research study found people with psoriasis were 56% more likely to have fungal nail infection than matched controls (4). Simply filling the crack with multiple layers of nail polish will help stop the fungus from reaching the nail bed.

3. Diabetes mellitus – Poor blood sugar control in Diabetics is known to reduce a person’s ability to fight infection and can cause excessive dryness in the skin of the feet. Research has demonstrated that Diabetics are almost three times more likely to catch onychomycosis (5) – you can help reduced this by maintaining good blood sugar levels and moisturising the feet daily.

4. Onychophagia – Medical jargon for Nail Biting! it’s true, biting your toenails (or picking at them) exposes the nail bed which allows fungus to enter (6), therefore stop picking your nails to keep them healthy, instead keep them short and smooth with an emery board.

5. Wet or sweaty feet – Fungus love dark, damp, warm environments, rotate footwear and wear fresh socks daily to keep sweat and moisture at bay.

6. Ill-fitting footwear – tight or shallow footwear can put pressure on and cause damage to the toenails, make sure all your footwear has a thumbs width distance between the end of the longest toe and the front of the shoe.

If you are unfortunate to have noticed a change in the colour of your nails book a consultation at Carlisle Foot Clinic by calling 01228 491002 or emailing contact@carlislefootclinic.com.

1. Hippocrates . Hippocrates. 1st ed. Vol. 2. London: Loeb Classical Library, No. 148, William Heinemann ltd; 1923. Prognostic; pp. 7–55.

2. Thomas J, Jacobson GA, Narkowicz CK, Peterson GM, Burnet H, Sharpe C. Toenail onychomycosis: an important global disease burden. J Clin Pharm Ther. 2010;35(5):497–519.

3. 10 Famous Celebrities Battling Toenail Fungus, Beaming Notes, Abhishek Dey, January 9, 2020, accessible via https://vt.beamingnotes.com/10-celebrities-battling-toenail-fungus/6/

4. Gupta, A.K., Lynde, C.W., Jain, H.C., et al. (1997) A higher prevalence of onychomycosis in psoriatics compared with non-psoriatics: a multicentre study. British Journal of Dermatology 136(5), 786-789

5. Al-Mutairi, N., Eassa, B.I. and Al-Rqobah, D.A. (2010) Clinical and mycologic characteristics of onychomycosis in diabetic patients. Acta Dermatovenerol Croat18(2), 84-91.

6. Westerberg, D.P. and Voyack, M.J. (2013) Onychomycosis: current trends in diagnosis and treatment. American Family Physician88(11), 762-770.