SymptomSkin, hair & nails
Thick Nails: Causes and Treatment
Thick nails are nails that have grown thicker, harder and often discolored, most commonly the toenails. The leading cause is a fungal nail infection (onychomycosis), followed by aging, repeated pressure from shoes or sports, and nail psoriasis. Thick nails are rarely dangerous, but they can be painful, hard to cut and, in people with diabetes or poor circulation, lead to infections. Treatment depends on the cause, so a diagnosis is worth getting.
Also called: Thickened nails, nail thickening, hypertrophic nails, onychauxis, ram's horn nails (onychogryphosis)
At a glance
- What it is
- Nails that become thicker than normal, often yellowed, crumbly or curved.
- Most common causes
- Fungal infection, aging, repeated trauma, nail psoriasis.
- Other causes
- Poor circulation, eczema, inherited conditions, long-term neglect (ram's horn nails).
- Diagnosis
- Examination plus nail clippings sent for fungal testing.
- Treatment
- Regular thinning and trimming, antifungal tablets or lacquers, psoriasis treatment.
When to get help
See a doctor within a day or two
- Redness, swelling, warmth, pus or spreading redness around a thick nail, especially if you have diabetes
- A dark streak or patch under a nail that is spreading onto the surrounding skin
- A painful thick toenail with skin breakdown or an ulcer underneath, in someone with diabetes or poor circulation
Book a routine appointment
- A thick, discolored nail that is getting worse or spreading to other nails
- Pain from a thick nail pressing in shoes
- Thick nails with pitting, a skin rash or joint pain, which may be psoriasis
- Difficulty trimming thick nails safely, particularly if you have diabetes or poor eyesight
Usually safe to manage at home
- Mild thickening of a toenail with age or after an injury, with no pain or infection
What thick nails look like
Thickened nails may be:
- raised and harder to cut
- yellow, white, brown or gray
- crumbly, chalky or ragged at the edges
- lifted from the nail bed (onycholysis), with debris underneath
- curved, ridged or claw-like
Toenails are affected far more often than fingernails, because they grow slowly, face pressure from shoes and live in warm, damp conditions.
Common causes of thick nails
Fungal nail infection
Onychomycosis causes about half of all nail problems. Fungi, often the same ones that cause athlete's foot, invade the nail, which becomes thick, yellow-white and crumbly, often starting at the tip and spreading back. Debris collects under the nail. It is more common with age, diabetes, sweaty feet, communal showers and athletic footwear.
Aging
Nails grow more slowly with age, and cells pile up, so nails thicken and become more brittle and ridged. Reduced circulation adds to this.
Repeated trauma
Pressure from tight or pointed shoes, running, soccer and dancing, or a single heavy injury, damages the nail matrix (the growth center). The nail may thicken permanently. Big toenails are most often affected. See nail trauma.
Nail psoriasis
About half of people with psoriasis have nail changes, and more with psoriatic arthritis. Look for pits (small dents), oily yellow-brown "salmon patches," crumbling, lifting of the nail and thickening with debris underneath. It can look like fungal infection, and both can occur together. See psoriatic nails.
Other causes
| Cause | Clues |
|---|---|
| Onychogryphosis (ram's horn nail) | Very thick, curved, horn-like nail, usually the big toe in older adults who cannot trim their nails |
| Poor circulation (peripheral arterial disease) | Thick, slow-growing nails with cold feet, shiny skin, hair loss on the legs and calf pain on walking |
| Eczema or lichen planus | Ridging and roughness with skin changes. Lichen planus can scar the nail |
| Diabetes | Higher risk of fungal infection and thickening |
| Pachyonychia congenita | Rare inherited condition with very thick nails from childhood |
| Yellow nail syndrome | Thick, slow-growing yellow nails with swollen legs and chest problems. Rare |
How doctors find the cause
A doctor, dermatologist or podiatrist will look at the nails, skin, feet and circulation and ask about injuries, footwear, psoriasis and diabetes. Because fungus and psoriasis look alike and treatment differs, guidelines recommend confirming fungal infection before long courses of antifungal tablets. This is done by sending nail clippings and debris for microscopy, culture or PCR testing. A nail biopsy is occasionally needed.
Treatment
Thinning and trimming
- Soak feet in warm water for 10 to 15 minutes to soften nails.
- Use sharp, straight-edged nail clippers, cutting straight across, and file down thickness with an emery board or nail file.
- A podiatrist can thin very thick nails with a burr painlessly. This is especially important for people with diabetes, poor circulation or poor eyesight, who should not cut thick nails themselves.
- Urea 40% creams or gels soften thick nails.
Fungal nail infection
- Oral antifungals: terbinafine is the most effective, usually taken for 6 weeks for fingernails and 12 weeks for toenails. Itraconazole is an alternative. Your doctor may check liver tests.
- Topical treatments: lacquers and solutions such as ciclopirox, efinaconazole and tavaborole, applied daily for up to 48 weeks. They work best for mild infection without involvement of the nail base.
- Removing the nail or laser treatment in selected cases.
Because nails grow slowly, a clear new nail takes 6 to 12 months (toenails) to grow out, and fungal infection often returns. Treat athlete's foot too.
Nail psoriasis
Topical steroids and vitamin D creams around the nail fold, steroid injections into the nail fold, and systemic or biologic treatments for widespread or severe disease.
Trauma-related thickening
Correct footwear and regular thinning. The nail matrix damage is usually permanent.
Prevention
- wear well-fitting shoes with room for the toes
- keep feet clean and dry, and change socks daily
- wear flip-flops in communal showers and pools
- treat athlete's foot promptly
- do not share nail clippers
- trim toenails straight across
Frequently asked questions
What causes thick toenails?
The most common causes are fungal nail infection, aging, repeated pressure or injury from shoes and sports, and nail psoriasis. Poor circulation, diabetes and long periods without trimming can also cause thick toenails. Testing nail clippings can confirm whether fungus is the cause.
How do you treat thick toenails at home?
Soak your feet in warm water, then trim the nails straight across and file down the thickness. Urea cream softens thick nails. Over-the-counter antifungal products help mild fungal infection, but prescription treatment is usually needed for thick, infected nails. People with diabetes should see a podiatrist.
Are thick nails a sign of a health problem?
Usually thick nails are caused by fungus, aging or injury. Sometimes they reflect psoriasis, poor circulation, diabetes or rarely inherited or lung-related conditions. If several nails are affected or you have other symptoms, see a doctor.
Can thick toenails go back to normal?
If the cause is fungal infection or psoriasis, treatment can let a normal nail grow out, which takes 12 to 18 months for big toenails. Thickening from permanent damage to the nail growth area or from aging usually does not reverse, but regular thinning keeps it comfortable.
Should I see a doctor for thick nails?
See a doctor if the nail is painful, red or swollen, if it is spreading to other nails, if you have diabetes or poor circulation, or if there is a dark streak under the nail. A diagnosis ensures you get the right treatment.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: Nail fungus, diagnosis and treatment
- American Podiatric Medical Association: Toenail Fungus
- MedlinePlus: Nail abnormalities
- NHS: Fungal nail infection
- National Psoriasis Foundation: Nail psoriasis