Thickening of toenails can be caused by several factors, with the most common being:

• Aging: Toenails naturally thicken as people age because the growth rate of the nail plate slows down and blood circulation to the extremities decreases, causing nail cells to build up

• Fungal infections (Onychomycosis): This is a very common cause where fungi or yeast infect the nail bed, especially in warm, moist environments. The infection causes the nail to thicken, discolor, crumble, and sometimes lift from the nail bed

• Psoriasis: A skin condition that can also affect nails, leading to thickening and other nail abnormalities

• Trauma: Injury to the nail or repeated trauma (like stubbing the toe or pressure from tight shoes) can cause thickening over time

• Other medical conditions: Diabetes, peripheral vascular disease, arthritis, and other systemic illnesses can contribute to nail thickening due to poor circulation or inflammation

• Chronic inflammation: Conditions like chronic paronychia (long-term inflammation of the nail folds) can cause nails to thicken and peel

In summary, thickened toenails result primarily from aging, fungal infections, psoriasis, trauma, and certain systemic diseases that affect nail growth and health. Proper diagnosis and treatment depend on identifying the underlying cause, especially to address fungal infections promptly to prevent complications