Diseases causing nail splitting (onychoschizia) often involve skin conditions like psoriasis, infections (fungal, bacterial), endocrine issues (thyroid, diabetes), nutritional deficiencies (iron, biotin, protein), and systemic illnesses (heart, liver, kidney disease, lupus, cancer), though injury, aging, and chemical exposure are also common culprits, affecting the nail's structure and moisture.
Vitamin and nutrient deficiencies
Some vitamin deficiencies can cause nail splitting. If you're not getting enough biotin or calcium, you may notice nail splitting and other nail changes. Nail splitting can also be a sign of low iron levels (anemia).
Nutrient Deficiencies
Biotin, also known as vitamin B7, is essential for maintaining strong nails, and its deficiency can lead to splitting and brittleness. A well-balanced diet that includes biotin-rich foods can help improve nail health and prevent splitting. Some biotin-rich foods to include in your diet are: Eggs.
The visual appearance of the fingernails and toenails may suggest an underlying systemic disease. Clubbing of the nails often suggests pulmonary disease or inflammatory bowel disease. Koilonychia, or “spoon-shaped” nails, may stimulate a work-up for hemochromatosis or anemia.
Liver failure nails often appear as Terry's Nails, characterized by an opaque white or "ground glass" look across most of the nail, with only a thin, brownish or pinkish band at the very tip and the half-moon (lunula) often disappearing, though other changes like ridges or yellowness (jaundice) can also occur, indicating systemic issues.
Yellow or opaque coloring. Brittle nails. Pitted nails (can easily break off or fall off) Linear depressions across the fingernail (called Beau's lines)
Symptoms of acute liver failure may include:
Heart failure nails often show nail clubbing, where fingertips enlarge and nails curve downward like an upside-down spoon due to poor oxygen flow, feeling soft and warm, but can also present as blueish tints (cyanosis) or splinter hemorrhages (tiny red lines under nails) from heart infections (endocarditis). Other signs can include Terry's nails (mostly white with a pink tip) or Mees lines (horizontal white bands). These changes signal serious underlying issues, requiring prompt medical evaluation.
Autoimmune diseases can affect your nails in various ways. If you have alopecia or Hashimoto's disease, your nails can become shaped like a spoon in a concave position. Alopecia can also cause your nails to become weak and crumbly. With Hashiomoto's, your nails may start splitting easily.
Nail changes in vitamin B12 deficiency present as hyperpigmentation of nails like bluish discoloration of nails, blue-black pigmentation with dark longitudinal streaks, and longitudinal and reticulate darkened streaks. The nail pigmentation associated with B12 deficiency is more frequent in patients with dark skin.
Patients with reduced plasma magnesium levels can develop soft, flaky nails that are inclined to break or split.
Biotin: Biotin is a B-complex vitamin, also referred to as vitamin B7, coenzyme R and vitamin H. Biotin helps promote keratin synthesis, which is a major building block of the cells in your nails, hair and skin. Consuming biotin-rich food may help strengthen your brittle fingernails and toenails.
Protein deficiency: Nails are mostly made up of protein (keratin). A diet lacking in protein can lead to weak and splitting nails⁶. Make sure you include enough sources of protein in your diet to encourage healthy nail growth.
Here's a comprehensive guide to ten nail diseases and disorders that deserve a closer look.
Chronic stress triggers hormonal changes that can disrupt your body's ability to produce healthy keratin—the protein that forms your nails. Elevated cortisol levels can also reduce blood flow to the nail matrix, slowing growth and making nails more prone to splitting.
Your kidneys can affect many parts of your body, including your nails. Some nail abnormalities are related to kidneys not working as well as they should. Your kidneys are responsible for filtering waste from your body, such as urea (nitrogen waste) and creatinine (creatine waste).
Fingernail problems like nail ridges, splitting, and redness — which may appear differently depending on your skin tone — can also point to a lupus diagnosis. Always talk with your rheumatologist if you develop any new or worsening symptoms that you believe may be related to your lupus.
Liver disease can cause several nail changes, most notably Terry's nails, where nails appear mostly white with a narrow pink band at the tip (like a "ground glass" look). Other signs include clubbing (nails curve downwards, thickening at the tips), yellowish discoloration, and sometimes nail separation (onycholysis) or ridges.
Three early warning signs of heart failure include persistent fatigue/weakness, shortness of breath (especially with activity or lying down), and swelling (edema) in your legs, ankles, and feet, often accompanied by rapid weight gain from fluid buildup, all signaling your heart isn't pumping efficiently enough. Other key indicators are a chronic cough (sometimes with pink mucus) and heart palpitations.
Numbness and tingling: Yes. Narrowed arteries caused by high cholesterol can restrict blood flow to the arms, legs, hands, or feet, leading to these sensations. Joint pain: Indirectly. High cholesterol contributes to inflammation, which may worsen existing joint discomfort, especially in patients with arthritis.
If there are symptoms of liver disease, they may include: Yellowing of the skin and the whites of the eyes, called jaundice. Yellowing of the skin might be harder to see on Black or brown skin. Belly pain and swelling.
Fetor hepaticus is a distinct smell on the breath of someone with liver disease. It happens when your liver can't filter certain toxic substances from your blood anymore. These substances build up in your blood and come out in your breath. You may also detect the same smell in your pee or sweat.
Some liver and kidney disorders and some urinary tract infections can turn urine dark brown. So can bleeding inside the body called a hemorrhage. A group of illnesses that mainly affect the skin or the nervous system, called porphyria, also can cause brown urine.