What Your Nails Say About Your Health: Warning Signs You Shouldn’t Ignore

Author: Isaac ONI B.Pharm

Medical Reviewer: Nnenna Chiloli, MBBS, MPH

Highlights

• A healthy nail is usually pinkish with a smooth surface, firm texture, and even growth.
• Your nails can reveal early warning signs for conditions like anaemia, infections, lung disease, and nutritional deficiencies.
• The colour, shape, and textural changes in your nails often point to disease processes inside your body.
• Not every change is necessarily considered to be serious; however, some require medical attention.
• Understanding nail symptoms helps you know when to watch closely and when to seek help.

Introduction

Nails are more than a cosmetic feature on the body. You probably think of your nails as something to trim, paint, or merely groom, but they’re more than this. Your nails are specially designed to act as quiet body messengers, revealing signals about what’s happening inside your body.

A healthy nail is hard but flexible. The surface is whitish, smooth, shiny, and free from ridges, pits, or splits. A healthy nail gives a translucent appearance with the pinkish colour of the nail bed showing through it. A healthy nail may look dry and hard, but its actual water content is between 15-25% [1]. 

In this article, you will learn about what different nail variations look like, the changes that should give you concerns and signal health issues, and when you should see a doctor. The end of this is to enlighten you and help you understand how your nails can help you detect health problems early.

Why Nail Health Matters

A nail is a horny structure formed by the invagination of the epidermis into the dermis. Your nails grow from a part of the skin called the nail matrix, which is located just under the cuticle. This matrix produces keratin, which is a protein that can also be found in your hair and skin [1].  Anything that affects the body’s ability to produce sufficient amounts of keratin can change how your nails grow.

What Affects Nail Health?

Several factors have been found to influence the appearance and strength of your nails:

• Nutrition: A lack of vitamins like iron, zinc, biotin, and vitamin B12 can make nails weak.

• Blood circulation: Poor or inadequate blood flow can hinder nail growth or change its colour.

• Infections: Fungal and bacterial infections can make nails become thick, discoloured, or brittle.

• Systemic diseases: Conditions such as thyroid disease, diabetes, lung disease, and heart issues often show early signs in the nails.

• Ageing: Nails naturally become more brittle and ridged as you age.

When nails begin to look different from their normal appearance, your body may be trying to tell you something.

Common Nail Changes and What They May Indicate

Your nails can change in colour, texture, shape, or thickness. According to the American Academy of Dermatology Association, while some changes are harmless, others may signal a deeper health issue. 

1. Colour Changes and Their Meaning

Red Nails

Red nails may indicate:

• Inflammation or infection
• Heart disease (in rare cases)
• Nail injury

Red discolouration has been associated with systemic illnesses such as cardiac issues [2].

White Nails (Leukonychia)

Leukonychia, also known as white nails, is usually harmless when it appears. It usually occurs after biting your nails, but they can sometimes signal severe systemic disorders or congenital conditions [3]. White nails may suggest:

• Low albumin levels (common in liver disease)
• Anaemia
• Fungal infections
• Minor nail injury

Yellow Nails

Yellowing of the nails often points to:

• Fungal infections
• Chronic lung conditions such as bronchitis
• Lymphatic system issues
• Excessive nail polish use

Research has found that Yellow Nail Syndrome is linked with respiratory disorders [4]. 

Blue Nails

What comes to mind readily when blue or bluish nails are observed is poor oxygen levels in the bloodstream.
Possible causes include:

• Lung disease
• Heart disease
• Raynaud’s phenomenon

A study by Parul Pahal and Amandeep Goya links nail cyanosis closely with heart and blood vessel health [5].

Black or Dark Nails

This is also referred to as melanonychia. It is caused by the build-up of pigments and can indicate multiple conditions, such as:

• Injury or bruising
• Fungal infections
• Melanoma- this is a type of skin cancer. 

You should see a doctor immediately if you notice black or dark nails appearing on your nails without injury. 

2. Texture Changes and Their Meaning

Brittle Nails

Brittle nails have been linked to nutritional deficiencies [6].Common causes of brittle nails are:

• Overexposure to water
• Ageing
• Hypothyroidism
• Iron deficiency 

Pitted Nails

Pitted nails are small dents or pits on the nails, often indicating:

• Psoriasis
• Nail eczema
• Autoimmune conditions

A study by Satyendra Kumar Singh found pitting as one of the early signs of nail psoriasis [7]. Peeling NailsOften results from:

• Frequent handwashing
• Chemical exposure
• Vitamin B deficiency

Thickened Nails

Thick nails may indicate:

• Fungal infection
• Peripheral artery disease
• Lung disease

3. Shape Changes and Their Meaning

Clubbed Nails

Clubbed nails can be described as when nails curve over rounded fingertips or toes. This condition is associated with:

• Lung disease
• Heart disease
• Inflammatory bowel disease
• Liver disease

Spoon Nails (Koilonychia)

Spoon-shaped nails may reflect:

• Iron deficiency anaemia
• Heart disease
• Hypothyroidism

Beau’s Lines

These are deep horizontal ridges across the nail that impede normal nail growth. They appear due to:

• Severe illnesses such as measles, mumps, and pneumonia
• Nutritional deficiency, like zinc deficiency
• Chronic conditions that interfere with blood flow to the nail matrix, such as hypothyroidism and diabetes
• Cytotoxic agents, such as docetaxel, used in chemotherapy, could also cause Beau’s lines [8].

Onychorrhexis

Usually, this is often harmless and related to ageing. It may also result from mild nutritional deficiencies. 

4. Lines and Spots

White Spots or leukonychia

This is usually harmless and often due to injury. Other possible causes include:

•  Heavy metal poisoning
•  Allergy
•  Heavy cosmetic use
•  Nutritional deficiency.

Dark Lines

This is similar to melanonychia described above. Dark lines should be examined by a doctor, especially if:

• A single dark stripe appears
• It spreads or darkens
• You have no history of trauma or accident

When to See a Doctor

Not all noticeable nail changes are dangerous. Some occur due to habits such as nail-biting, frequent washing with soap, or using harsh chemicals. However, you should book an appointment with a medical practitioner if you notice any of the following:

• A dark streak or line under the nail (melanonychia)
• Nails separating or splitting from the nail bed
• Severe thickening, crumbling, or falling off of nails
• Sudden colour changes that spread (blue, black, or white)
• Clubbing or spoon-shaped nails
• Persistent pain or swelling around the nail

These may indicate underlying diseases, including heart, liver, lung, or autoimmune disorders.

Conclusion

Your nails are more than just part of your beauty routine. As described above, many nail changes are harmless; however, some may be early warning signs of medical conditions like anaemia, fungal infections, lung disease, or thyroid disorders. Paying attention to the colour, shape, and texture of your nails helps you know when to take action and when to seek medical help. 

References

1. Kumar Vivek, Shamar Sangeet, Naveen, Jalwal Pawan. A comprehensive review on human nails. International Journal of Medical and Health Research; 2017 [cited 2025 Nov 23]. Available from: https://www.medicalsciencejournal.com/assets/archives/2017/vol3issue10/3-10-28-175.pdf

2 Gollins CE, de Berker D. Nails in systemic disease. Clin Med (Lond). 2021 May [cited 2025 Nov 23];21(3):166–9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8140692/

3. Pakornphadungsit K, Suchonwanit P, Sriphojanart T, Chayavichitsilp P. Hereditary Leukonychia Totalis: A Case Report and Review of the Literature. Case Reports in Dermatology. 2018 Apr 12 [cited 2025 November 24];10(1):82–8. Available from: https://karger.com/cde/article/10/1/82/329295/Hereditary-Leukonychia-Totalis-A-Case-Report-and

4. Xu S, Wu X. Respiratory manifestation of yellow nail syndrome: a case report and literature review. The Journal of International Medical Research [Internet]. 2021 Dec 1 [cited 2025 November 24];49(12):3000605211063313. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8670787/

5. Pahal P, Goyal A. Central and Peripheral Cyanosis. PubMed. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2025 Nov 24]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK559167/

6. Seshadri D, De D. Nails in nutritional deficiencies. Indian J Dermatol Venereol Leprol 2012 [cited 2025 Nov 24];78:237-241Available from: https://ijdvl.com/nails-in-nutritional-deficiencies/

7. Singh S. Finger nail pitting in psoriasis and its relation with different variables. Indian Journal of Dermatology. 2013 [cited 2025 Nov 24];58(4):310. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3726881/

8. Masato Shimozono, Takafumi Kato. Beau’s Lines on Fingernails and Toenails. JMA Journal. Jmaj.jp. 2025 [cited 2025 Nov 24]. Available from: https://www.jmaj.jp/detail.php?id=10.31662%2Fjmaj.2025-0326

Disclaimer:
The information provided on this website is for general educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Published November 25, 2025