What should you know about running thick toenails?

Repeated impact, a tight toe box, or a toenail that rubs against the shoe can make the nail grow unevenly, lift, split, or become difficult to trim. Fungal nail infection may cause yellow or white colour, crumbly material, or debris beneath the nail. Nail psoriasis can produce pits, ridges, separation, or a yellow-red patch. A clinician can examine the nail and, when needed, test a sample before treatment.

Choose running shoes with enough room for the longest toe and keep nails trimmed straight across without cutting into the corners. Keep feet dry, change damp socks, and avoid sharing nail tools. Do not pull off a lifted nail or apply a prescription antifungal without assessment. Learn about [Nail Fungus](/conditions/nail-fungus/) and [Nail Psoriasis](/conditions/nail-psoriasis/); treatment may include [Oral Antifungal Treatment](/treatments/medical-dermatology/oral-antifungal-therapy/) when infection is confirmed.

Arrange a dermatology review if one nail changes without an obvious running injury, the nail is painful or repeatedly catches, or colour extends into nearby skin. Seek prompt care for spreading redness, warmth, swelling, pus, fever, or a dark mark that does not grow out. People with diabetes, reduced circulation, or reduced sensation should have foot changes assessed early.

Could shoe pressure explain this pattern, or should the nail be tested? Is the nail attached or lifting from the nail bed? Which trimming and running adjustments are suitable? Would [Laser Treatment For Nail Fungus](/treatments/laser-and-energy/laser-nail-fungus-treatment/) be relevant if fungus is confirmed?