Brittle Nails

Fragile nails that split, peel or break easily. About 20% of adults are affected, women about twice as often as men, and the frequency rises with age (up to 35 to 50% in older women).

• Two patterns:
  • Onychoschizia: horizontal splitting and peeling of the distal nail plate into layers (lamellar dystrophy).
  • Onychorrhexis: longitudinal ridging, with splitting and fissuring of the nail plate.
• Mechanisms: repeated wetting and drying, which causes the nail plate to swell and shrink and loosens the intercellular lipid bonds, and the loss of nail plate water content (normal 18%, brittle nails below 16%).
• Causes:
  • Exogenous (the majority): wet work, frequent hand washing, detergents, solvents, acetone nail polish remover, nail enamel and hardeners, artificial nails, trauma and nail biting.
  • Ageing: slow nail growth with thinned plates, and ridging.
  • Systemic: iron deficiency, hypothyroidism and hyperthyroidism, peripheral vascular disease, Raynaud phenomenon, protein deficiency, zinc deficiency, and hypovitaminosis (A and C).
  • Dermatological: psoriasis, lichen planus, eczema of the nail fold, onychomycosis and alopecia areata.
  • Drugs: retinoids (isotretinoin, acitretin), taxanes, EGFR inhibitors, and ciclosporin.

• Dry, rough, thin nails with lamellar splitting at the free edge, or longitudinal ridges and splits that can extend toward the nail fold. The nails may snag and catch on clothing.
• Fingernails are more commonly affected than toenails. Pain and nail fold damage may occur if the splits are deep.
• Associated findings guide cause: koilonychia (spoon nails) and pallor in iron deficiency, pitting and onycholysis in psoriasis, fissured thickened nails with scale in onychomycosis, and a thin ridged nail with pterygium in lichen planus.
• Differential diagnosis: onychomycosis, nail psoriasis, nail lichen planus, eczema, pseudomonas infection (green discolouration), brittle nail syndrome from age, and nail patella syndrome.
• Red flags: a single nail with a persistent split or ridge, a pigmented band, or a destroyed nail (consider tumour).
• Complications: pain, snagging, secondary paronychia and cosmetic distress.

• Clinical. Ask about wet work, nail cosmetics, solvents, trauma, diet, drugs, and symptoms of thyroid and iron deficiency.
• Examine all nails, nail folds, skin and hair for psoriasis, lichen planus and eczema. Check peripheral pulses and for Raynaud phenomenon.
• Laboratory tests when the cause is unclear or the history suggests it: full blood count, ferritin, thyroid function tests, zinc, vitamin B12, folate, and 25-hydroxyvitamin D.
• Nail clippings for potassium hydroxide preparation, fungal culture or periodic acid Schiff stain if onychomycosis is possible.
• Biopsy of the nail matrix or nail bed for atypical or single nail disease, and nail biopsy in suspected lichen planus.

• Protect the nails from water and chemicals, the single most useful measure:
  • Wear cotton lined gloves under vinyl or nitrile gloves for wet work, dishwashing and cleaning, and cotton gloves for dry work.
  • Limit hand washing where possible, and use soap free cleansers.
  • Avoid acetone containing polish removers (use acetone free removers sparingly), nail hardeners with formaldehyde, artificial nails and glues.
  • Keep nails short, file them gently in one direction using a fine glass or emery file, and avoid cutting wet nails. Do not use nails as tools, and avoid biting and picking.
  • Do not remove the cuticle or push back nail folds.
• Moisturise: apply urea 10 to 20% cream, lanolin, or a petroleum based emollient to the nails and nail folds after hand washing and at bedtime, massaging into the nail fold. Wear cotton gloves overnight to enhance absorption.
• Nail lacquers: a clear nail polish or a hydroxypropyl chitosan lacquer (evidence limited) protects the free edge and reduces water loss. Remove and replace weekly with an acetone free remover.
• Biotin 2.5 mg orally once daily for 3 to 6 months improves nail plate thickness and splitting in some studies (evidence limited), and doses above 5 mg cause interference with troponin, thyroid hormone and other laboratory immunoassays, so stop the supplement for at least 2 to 3 days before blood tests.
• Treat the cause:
  • Iron deficiency: ferrous sulphate 200 mg orally once daily or on alternate days for 3 to 6 months.
  • Hypothyroidism: levothyroxine 1.6 micrograms/kg per day with monitoring of thyroid stimulating hormone. Hyperthyroidism: carbimazole 15 to 40 mg daily under specialist care.
  • Psoriasis: potent topical steroid (betamethasone valerate 0.1%) with or without calcipotriol to the nail fold, or intralesional triamcinolone acetonide 2.5 to 5 mg/mL, 0.1 mL per site, every 4 to 6 weeks, for nail matrix disease.
  • Lichen planus: intralesional triamcinolone 5 to 10 mg/mL, or oral prednisolone 0.5 mg/kg per day for a short period under specialist care.
  • Onychomycosis: terbinafine 250 mg daily for 6 weeks (fingernails) after confirmation.
  • Drug induced: review the causative drug with the prescriber.
• Special groups:
  • Pregnancy: avoid high dose supplements and oral retinoids, and use emollients and protection.
  • Elderly: expect ageing related brittleness, reduce wet work, and provide gentle nail care.
  • Hairdressers, cleaners, nurses and food handlers: optimise glove use and workplace hand care.
  • Children: nail biting and picking need behavioural management.
• Follow up: nails take 4 to 6 months to regrow in the fingers, so review at 3 and 6 months. Refer to dermatology for suspected psoriasis, lichen planus, a single abnormal nail, or failure of measures.