What Causes Thick Yellow Toenails?

Fungal nail disease may make a nail yellow, crumbly, or separated from the nail bed. A nail repeatedly squeezed by tight shoes can thicken or grow unevenly after trauma. Nail psoriasis may cause pitting, lifting, or yellow-brown discolouration and can occur with skin or joint symptoms. A clinician may examine the nail and, when needed, test a clipping before choosing treatment, because appearance alone cannot reliably identify the cause.

Keep feet clean and dry, change damp socks, and choose shoes with room around the toes. Trim nails straight across after softening them, and avoid digging under the nail or sharing clippers. Do not paint over a changing nail for long periods if you need it assessed. If fungus is suspected, ask about [Nail Fungus](/conditions/nail-fungus/) and whether [Oral Antifungal Treatment](/treatments/medical-dermatology/oral-antifungal-therapy/) or another option fits your health history.

Arrange an assessment if the nail keeps thickening, affects walking, or does not improve with basic protection. Seek prompt care for spreading redness, warmth, swelling, drainage, marked pain, or fever. If you have diabetes, reduced circulation, or reduced sensation in your feet, arrange professional nail and skin advice early. A dark streak, bleeding, or a change limited to one nail also deserves examination.

Could this be fungus, psoriasis, or damage from footwear? Would a nail sample clarify the diagnosis? Which treatments are suitable with my medicines and medical conditions? Would [Nail Psoriasis](/conditions/nail-psoriasis/) or [Laser Treatment For Nail Fungus](/treatments/laser-and-energy/laser-nail-fungus-treatment/) be relevant?