Our nails can tell a lot about our health. As far back as the fifth century, Hippocrates described nail clubbing as an important clue to a myriad of diseases, and it has since been associated with many systemic diseases. Today, doctors look at abnormalities in the nail’s shape, the nail’s surface, the way in which it attaches to the skin, abnormalities in the fingernail moons (the lunula) found at the base of the nail, and nail colour – all of which can be symptomatic of another illness.
In our series on nail health, we look at nail colour issues and their most common underlying causes. While seeing a change to your nails or the half-moons doesn’t always mean that you have a disease, it can be a warning sign of a specific disease, and thus advisable to consult with a healthcare professional.
| Issue | Common cause |
|---|---|
| Pale nail | Anaemia |
| White spots | Injury, infection, allergic reaction, mineral deficiency |
| White discolouration | Mees lines (a single or multiple whitish lines running along the width of the nail): these have been reported with conditions such as Hodgkin’s disease, leprosy, tuberculosis, malaria, herpes zoster, chemotherapeutic drugs, carbon monoxide (CO) and antimony poisoning, renal and cardiac failure, pneumonia, and childbirth. Muehrcke’s lines (double white lines running across the nail): these are seen in nephrotic syndrome, glomerulonephritis, liver disease, chemotherapeutic drugs, and malnutrition. Terry nails (half the nail is white, and the other half is normal): it is associated with congestive cardiac failure, adult‑onset diabetes mellitus, peripheral vascular disease, hemodialysis, and HIV. |
| Yellow discolouration | Nail infection, nicotine stains, rheumatoid arthritis, or a severe form of liver disease. |
| Yellow to yellow‑green discolouration | This is often caused by swelling due to the build-up of lymph fluid in the body (lymphedema) and compromised respiration due to conditions such as fluid around the lung (pleural effusion). |
| Brown discolouration | Half and half nail/Lindsay nail (one half of the nail is white, while the other half is brown): this is often seen in people with chronic kidney disease. |
| Brownish-black pigmentation | This can be normal for people with a darker skin tone. However, this can also occur due to dark skin patches (melanocytic nevus), malignant melanoma, medication (e.g. antimalarials, minocycline, phenytoin, psoralens, sulfonamides, zidovudine, doxorubicin, methotrexate, azathioprine), malnutrition, thyroid disease, smoking, HIV and Addison’s disease. |
| Greenish black | A nail infection caused by bacteria. |
| Black lines/ dark streak | Black lines can be a sign of injury. A dark streak could be melanoma, a type of skin cancer. |
| Blue or purple discoloration | Blue nails are a sign that there isn’t enough oxygen in your bloodstream. This can be caused by narrowing of the blood vessels (vasoconstriction) and diminished peripheral blood flow which occurs with cold exposure, shock, congestive cardiac failure, and vascular disease. |
| Red half-moons | This can be seen in collagen vascular disease, cardiac failure, chronic obstructive pulmonary disease (COPD), cirrhosis, chronic urticaria, psoriasis and CO poisoning. |
| Dusky red half-moons | Could be a sign of lupus, heart disease, alopecia areata, arthritis, dermatomyositis. |
| Blue half-moons | This could be a sign of poisoning. |
References:
1. American Academy of Dermatology Association. (n.d.), 12 Nail changes a dermatologist should examine. American Academy of Dermatology Association [Online]. Accessed on 31 January 2023. Available from https://www.aad.org/public/everyday-care/nail-care-secrets/basics/nail-changes-dermatologist-should-examine
2. Rasminsky, A. (2021). From Ridges to Peeling: What These 8 Fingernail Signs Say About Your Health. Healthline [Online]. Accessed on 31 January 2023. Available from https://www.healthline.com/health/beauty-skin-care/healthy-nails
3. Singal, A., & Arora, R. (2015). Nail as a window of systemic diseases. Indian Dermatology Online Journal, 6(2), 67–74. https://doi.org/10.4103/2229-5178.153002