Onychophosis: Throw the kitchen sink at it

Onychophosis is a very common reason for pain down the side of toenails, most commonly the big toenail. This is most commonly searched for online as the “side of the toenail hurts, but is not ingrown“, which is a good summary of what it is. A true ingrown toenail is when the nail actually penetrates the skin. With an onychophosis the nail plate pushes on the skin to become painful but does not actually penetrate the skin.

Causes of Onychophosis

Anywhere there is too much pressure on the skin, it thickens up to protect itself. Too much pressure under the foot can result in a plantar callus. Too much pressure on a toe can cause a corn. Too much chopping of wood can result in calluses on the hand. If that pressure continues, the skin keeps on becoming thicker and can become so thick that it becomes painful.

This is what causes an onychophosis – there is too much pressure between the nail plate and the nail groove down the sides of the nail. As a result of this pressure a callus may develop and if the pressure is more focused on a smaller area a corn may develop. If there is a sharper edge or corner on the nail, then the nail may actually penetrate the skin and cause an ingrown nail rather than an onychophosis.

This is more common if the nail plate is more curved and can put more pressure on the nail groove. It can also be more common with tighter fitting footwear that pushes the skin of the nail groove up against the nail plate.

Symptoms of Onychophosis

The main symptom is pain down the side of the nail that develops slowly. It is usually worse wearing shoes. A true ingrown nail is likely to be of a sharper pain and perhaps show signs of an infection.

Treatment of Onychophosis

There is not a lot that can be done to self-treat an onychophosis. This really does need to be skillfully debrided by a competent podiatrist. They will typically use a ‘Blacks’ file to file the nail away from the painful callus or corn and then use a fine scalpel down the nail groove to reduce the callus or corn. This can recur as the nail grows out and will often need to be repeated periodically.

Urea-based emollients may be useful to apply down the edge of the nail groove to try and prevent a recurrence. The footwear needs to be such that it does not put pressure on the nail groove and sometimes padding can be used to stop the second toe rubbing on the big toe may help.

If the problem is particularly painful and keeps recurring then a partial toenail removal could be considered. This is normally done under a local anesthetic and removes the edge of the toenail that is causing the problem.

Podiatrist debriding an onychophosis:

Forum discussions on Onychophosis

Not an ingrown toenail?

Personal Opinion on Onychophosis

You need a skilled podiatrist to deal with this either with regular debridement or to do a partial nail removal to remove the edge of the nail that is causing the pressure. They are really your only two best options.


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