The nails on my toes are yellowish, what is the likely reason for that?

Fungus: One common cause for discolored or misshapen toenails is a fungal infection of the nails. This is not serious, but can be bothersome. Treatment is available but can take months to work or may not be covered by insurance. If the toes are painful, red or swollen see a doctor. Good luck!

Fungus: Yellow discoloration is usually a sign of fungus of the toenail.

Possible: Fungus. See podiatrist who will take a small portion of nail for biopsy to make sure its fungus vs micro trauma or something else. Many treatment options for fungus are available. See your local podiatrist.