What causes dry, brittle nails?

Nails become fragile when the nail plate loses moisture or is repeatedly stressed. Frequent handwashing, cleaning products, acetone, gel removal, picking, biting and filing in one direction can all contribute. Splitting at the tips may follow minor injury or habitual pressure.

Eczema or psoriasis around the nails can change their surface. A fungal nail infection may cause thickening, discoloration, crumbling or separation from the nail bed; see Nail Fungus for related information. Less commonly, changes affecting many nails can accompany nutritional deficiency, thyroid problems or another medical condition. A clinician may examine the nails and review medicines, diet and general symptoms.

Keep nails trimmed and smooth rough edges with a fine file. Wear protective gloves for prolonged contact with water or cleaning chemicals, and use a fragrance-free hand and nail moisturiser after washing. Avoid peeling polish, cutting the cuticles, biting nails and using nails as tools. Leave space between manicures so the nail surface can recover.

Take a clear photograph if the change is progressing, and note whether one nail or several are affected. Do not start high-dose supplements without medical advice; the useful treatment depends on the cause.

Arrange a dermatology or primary-care assessment if brittleness persists despite gentler nail care, affects several nails, or comes with pain, swelling, pus, marked discoloration, bleeding or nail separation. Seek prompt care for rapidly worsening redness or severe tenderness around a nail. A new dark streak, especially one extending onto nearby skin, should be assessed rather than covered with polish.

Ask whether the nail pattern suggests irritation, fungal infection, eczema, psoriasis or another cause; whether a nail sample or blood tests are appropriate; and which products or medicines you should stop or continue.