What Causes Toenails to Thicken?

1. Onychomycosis

Onychomycosis is a fungal illness that is the most common cause of thick toenails.

Because fungus flourishes in warm, damp environments, your toenails are susceptible to fungal infections. Onychomycosis can also occur when a person wears the same sweaty shoes or boots every day or works in wet, rainy conditions. 

The fungus may only produce slight discoloration of the nail in the early stages, but as the condition progresses, the nail may become hard and thickened. In severe cases, the thicker nail eventually splits away from the nail bed. People with diabetes are at high risk of fungal infections.

2. Microtrauma

Damage to the nail bed due to an injury can result in thick nails. Toenails that have been damaged can regrow thicker than before. 

Microtrauma typically affects one or two toes. However, if it occurs frequently, it may cause more damage or affect all toes. The most common cause of microtrauma to the toenails is ill-fitting shoes.

3. Psoriasis

Psoriasis is an autoimmune condition that causes scaly, red areas on the skin and is frequently associated with thickening of the fingernails and toenails. Psoriasis can cause ridges to form on the nails and loosening of the nails from the nail bed.

4. Paronychia

Paronychia causes redness and swelling around the nail. Multiple infections can cause thickening of both fingernails and toenails over time.

5. Aging

Your toenails can start to thicken as you get older, since your body’s cell turnover rate decreases with age.

In the early stages, thick toenails may go unnoticed. However, symptoms that may appear include:

• Brittle, easily broken nails
• Unpleasant odor from the nails
• Nails that lift easily from the nail bed
• Difficulty cutting or trimming the nails
• Nail cracking or splitting (common)
• Accumulation of dirt and debris beneath the nails
• Pain or discomfort
• Scaling on the surface of the toenails as they thicken over time

Thick toenails can be reversed if the underlying cause is addressed or proper preventative measures are taken.

Polishing rough surfaces to make them smoother is a great way to treat thick toenails. Avoid pedicures because they may cause fungal infection to flare up when cuticles are removed. 

Doctors may suggest drugs such as topical steroids or injections in the case of systemic diseases. As the nail grows out, fungal infections may require months of treatment, which include:

• Prescription creams or ointments
• Oral drugs
• Nail removal to treat the nail bed beneath
• Laser therapy