Onychauxis is a uniform hypertrophy or thickening without deformity of whole nail plate. The thickening occurs at matrix and it is thought that trauma to the nail matrix results in increased production of onchyocytes. If there is a deformity of the nail plate with thickness, then that is called onychogryphosis. Onychauxis is common and in some settings is abbreviated as ‘O/X’ in clinical notes.

Maybe associated with minor repetitive trauma to the nail (eg wearing tight fitting shoes) or acute trauma. There may be a mallet toe present that exposes the toe nail to distal pressure on the ground. May be caused by a fungal infection or an underlying condition such a psoriasis or eczema. Poor circulation in the elderly has been associated with it. There was an old case reported of hypogonadism whose onychauxis reversed when androgen levels were restored (Lisser, 1924). It is also seen in Hansen’s disease (leprosy).

Clinical Features:
Nail appears more opaque than normal translucent pink appearance – may have a light brown discoloration.
Subungual hyperkeratosis and debris is common.
Most commonly, the hallux and fifth toenails ares involved – but others can be involved (all nails or isolated nails).
Nail cutting is difficult and often neglected.
Shoe pressure may cause pain.
Pressure may result in a subungual aseptic necrosis.

Differential diagnosis: onychomycosis; onychogryphosis; pachyonchia congenita
The ICD-10-CM diagnosis code for onychauxis is L60.2

Management of Onychauxis:
As damage to the nail matrix is irreversible, there needs to be regular reduction of nail plate with nail cutters and nail drill/burr
Check footwear fitting for pressure on the toenails.
Those with an underlying skin condition may see an improvement in the onychauxis when there is an improvement in the skin condition.
Maybe permanent surgical removal of the nail if particularity problematic.

Page last updated: @ 5:27 am


4 Responses to Onychauxis

  1. Tim July 23, 2022 at 5:11 pm #

    Would applying tazarotene to the posterior nail fold that covers the nail matrix or applying tazarotene to the nail bed once the nail is removed and the nail bed healed reverse onychauxis? It seems like it could work as Tazarotene seems to reverse the process that causes onychauxis due to trauma.

    • Staff July 23, 2022 at 8:13 pm #

      Interesting idea. Theoretically possible. The question would be if it could penetrate deep enough into the nail matrix. Would need for someone to do a trial on it.

      • Tim July 24, 2022 at 5:13 pm #

        Well I’m no podiatrist but maybe you could get in contact with someone about doing a study.

      • Tim July 26, 2022 at 12:57 am #

        Tazarotene is used for psoriatic toenails with good effect. Psoriatic nails cause hyperkeratosis of the nails and nail bed and Tazarotene is used for that. So I was thinking, psoriasis cause the same effect in nails as does trauma to the nail that causes onychauxis.