Brittle Nails

What is it?

Brittle nails (onychoschizia) is a very common complaint, particularly in women. The nail plate is 10% water; repeated wetting and drying cycles dehydrate the nail and cause horizontal lamellar splitting. Hypothyroidism is the most important systemic cause of brittle nails — it also causes hair loss, cold intolerance, and fatigue. Iron deficiency causes koilonychia (spoon-shaped nails) and brittleness. Biotin deficiency is often cited but is rare — supplementation only benefits those who are truly deficient. Fungal nail infection (onychomycosis) causes thickened, crumbly, discolored nails and accounts for up to 50% of nail complaints in clinical practice.

Common causes

When to see a doctor

• 1Thickened, yellow-brown, or crumbly nails — likely onychomycosis requiring antifungal treatment
• 2Brittle nails with fatigue, hair loss, and cold intolerance — screen for hypothyroidism
• 3Spoon-shaped nails (koilonychia) — evaluate for iron deficiency anemia
• 4Brittle nails with skin changes and joint pain — evaluate for psoriatic arthritis
• 5Nail pitting, onycholysis, or oil-drop sign — evaluate for psoriasis

What you can do

• ✓Keep nails hydrated — apply nail oil or hand cream, focusing on the nail plate and cuticle
• ✓Wear gloves when washing dishes or working with chemicals
• ✓Limit acetone-based nail polish removers — use acetone-free alternatives
• ✓Keep nails short during recovery to minimize leverage forces causing breakage
• ✓Biotin supplements (2.5 mg/day) may improve brittleness in some individuals over 6+ months

Conditions that cause this symptom

Medications that may help

Treatment depends on the underlying cause. Always consult your provider before starting any medication.

Frequently asked questions