Brittle splitting nails (onychoschizia) is a condition characterized by weak or thin fingernails or toenails that easily split and break.  It mostly affects women and may occur if nails are either dry and brittle from too little moisture, or soft and brittle from too much moisture.

Repeated wetting and drying of nails is the chief cause of brittle splitting nails. Factors that may worsen the condition include use of harsh chemicals, such as nail polish remover or detergents, sun exposure, low humidity, and dry, cold weather. In rare cases, the condition may be due to a vitamin deficiency or internal disease.

Brittle splitting nails is a condition marked by thin or weak fingernails or toenails that are prone to chipping, splitting, pealing and breaking. Also known as onychoschizia, the condition can occur if nails are either dry and brittle from too little moisture, or soft and brittle from too much moisture.

Nails consist of layers of a protein called keratin. Each nail is made up of several parts, including the following:

• Nail plate. Part of the nail that is most visible.
  
  
• Nail folds. The skin that borders the nail on three sides.
  
  
• Nail bed. Skin beneath the nail plate.
  
  
• Cuticle. Tissue that overlaps the nail plate at the base of the nail.
  
  
• Lunula. White shape that resembles a half–moon at the bottom of the nail.

As new cells grow, older cells harden and are pushed up toward the end of the fingertip. Nails also are permeable, or let in liquids that come into contact with them. These liquids can cause nails to become either too moist or too dry. Either state can cause nails to become brittle. When this happens, they often split – either vertically (onychorrhexis) or horizontally (lamellar onychoschizia) – or soften.

Repeated wetting and drying of nails is the chief cause of brittle splitting nails. In addition, use of some nail polish removers (particularly those with acetone), nail hardeners and other chemicals that may come in contact with nails also may contribute to the problem. Detergents and other harsh cleaning products can damage several layers of the nail.  Low humidity and dry weather and excessive sun exposure can exacerbate the condition as well. However, contrary to common belief, nail polishes do not harm nails. In fact, they actually prevent detergents from damaging the nails while also locking moisture into the nails.  

Repetitive trauma to the fingernail, such as from typing and other activities, can also cause a person to develop brittle splitting nails.

In rare cases, internal disease or vitamin deficiencies – such as a lack of iron or zinc – may be the cause of brittle splitting nails. Examining the nails of both the fingers and the toes may offer clues as to whether or not an internal disease is responsible for brittleness. If both the fingernails and toenails are split, an internal disease, such as thyroid problems, or low levels of zinc and iron may be responsible. If the fingernails are split, but the toenails remain strong, external factors are likely contributing to the problem. Brittle nails may also result from underlying skin conditions such as lichen planus.

More than 20 percent of the United States population has brittle nails, according to the American Academy of Dermatology. Brittle splitting nails most commonly affect women. The condition is also more common in older adults. This is due to the fact that nails grow more slowly as people age. The nails of older people have also undergone more exposure to sun and other conditions that cause brittle splitting nails.

Patients who have trouble with brittle splitting nails should consult a dermatologist about the best way to treat the condition. Brittle splitting nails are often treated by applying lotions that contain alpha hydroxy acids or lanolin. These substances can be applied to nails both before and after wetting the hands. Agents with urea or lactic acid are also effective at treating dryness. Taking a multivitamin with iron, zinc and biotin may increase the strength of nails. Olive oil is also an inexpensive treatment.

In addition, people can take other steps to prevent their nails from become brittle. It is best to avoid allowing the nails to repeatedly become wet and dry. Cotton-lined rubber gloves can protect the nails by keeping them dry during household chores, such as dishwashing. The gloves will also protect the nails from exposure to harsh cleaning products. People with an occupation that involves frequent wetting and drying of the nails (e.g., dishwasher, hairdresser) may benefit from wearing gloves at the workplace.

Soft nails often indicate that too much moisture is present, or the nails have been damaged by detergents, cleaning fluids, nail polish removers and other chemicals. An application of a clear nail prep or nail polish with nylon fibers (known as fibered nail hardeners) may help strengthen the nails. Nail hardeners the contain toluene sulfonamide or formaldehyde should be avoided, as these can irritate the skin.

Low-grade nail polish products should not be used, as they can cause extreme drying and brittleness. Nail polish remover that contains the ingredient acetone is especially likely to dry out nails. It is better to choose a nonacetone nail polish remover. In addition, nail polish remover should be used no more than once a week to prevent excessive drying.

Proper care of nails can help them from becoming too brittle. Nails should be shaped and filed with a very fine nail file, and the tips should be rounded gently. Nail irregularities that are filed promptly can help prevent breakage or splitting. Buff nails in the same direction as the nail grows – buffing “back and forth” can promote nail splitting. Do not use metal tools on the nail surface to push back the cuticle, as this can remove protective cells from the nail surface. Splits and tears in nails can be fixed by applying nail glue or clear nail polish. In addition, frequent manicures by a trained manicurist can help keep nails in a healthy condition.

People with brittle nails may use a moisturizer at night and sleep with their hands in cotton gloves. Finally, nails should not be used as a tool. Do not dial the phone with nail tips or use them to perform other chores, such as opening soda cans. This can weaken the nails and lead to breakage.  If trauma to the nails cannot be avoided, it is best to cut the nails short.

In the rare situations where internal disease is responsible for brittle splitting nails, the underlying condition will need to be diagnosed and treated before nails can be restored to health.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to brittle splitting nails:

1. Do my symptoms indicate brittle splitting nails?
   
   
2. Should I be concerned over the fact that I have brittle splitting nails?
   
   
3. What actions may have caused me to develop brittle splitting nails?
   
   
4. Is it possible that an internal disease is behind my brittle splitting nails?
   
   
5. What are my treatment options?
   
   
6. How can I prevent brittle splitting nails?
   
   
7. Should I avoid nail polish?
   
   
8. Would I benefit from taking vitamin supplements?