If you’ve ever taken a long bath or spent time in a pool, you’ve probably noticed your fingers pruning. The tips of your fingers, and sometimes the fingers as a whole, develop wrinkles and creases that resemble those on a prune.

Pruning by itself is generally harmless and goes away on its own. Extended pruning or pruning that doesn’t occur as a result of water, however, can be a symptom of an underlying medical issue.

The medical community used to believe that pruning was caused by your fingers absorbing water. It is now known that pruney fingers are the result of blood vessels that constrict below the surface of the skin. The condition is tied to the function of the nervous system.

Water can have this effect, but there are other causes as well. For instance, the pruning can happen due to fluid or nerve damage, both of which can signal an underlying medical condition.

While pruney fingers due to immersion in water is not a problem and will resolve quickly once the fingers are dry, other conditions can cause pruning without water.

Dehydration

When you don’t drink enough water, your skin loses some of its elasticity. This can result in pruney fingers and other parts of your body.

Adults should drink six to eight glasses of water per day, especially during or after exercise, or in hot weather.

Other drinks, such as juice, soft drinks, and even tea, can make you more dehydrated. For this reason, don’t include these types of drinks when measuring your water intake. Other symptoms of dehydration include:

  • fatigue
  • dry mouth
  • dark yellow urine
  • dizziness
  • headaches
  • increased thirst

Learn more about dehydration.

Diabetes

High blood glucose levels from any type of diabetes can cause pruney fingers. Diabetes can damage the sweat glands, and the lack of sweat can cause dryness. There are three types of diabetes: type 1, type 2, and gestational. Many of the symptoms overlap between the three variations and include:

  • frequent urination
  • increased thirst
  • extreme hunger
  • fatigue
  • high ketones in urine
  • blurred vision
  • unexplained weight loss
  • frequent infections

Learn more about type 1 and type 2 diabetes.

Thyroid disorder

The thyroid gland — which is inside the neck and shaped like a butterfly — is responsible for body temperature and metabolism regulation.

Your thyroid regulates how you break down food and whether that food is used for immediate energy or is stored away.

Those with a thyroid disorder can have pruney fingers, as well as a skin rash, which can also cause prune-like wrinkles. Thyroid disorders have other symptoms as well, depending on the type:

Hypothyroidism

  • puffy face
  • fatigue
  • constipation
  • weight gain
  • increased sensitivity to cold
  • pain and stiffness in the joints
  • thinning hair

Hyperthyroidism

  • sudden weight loss
  • sweating
  • increased appetite
  • tremor
  • increased sensitivity to heat
  • fine, brittle hair
  • menstrual changes

Learn more about hypothyroidism and hyperthyroidism.

Lymphedema

Swelling in the arms and legs is referred to as lymphedema. In most cases, just one limb is affected. But sometimes it can affect both arms or both legs. The swelling is caused by a blockage in the lymphatic system, usually as a result of the removal of or damage to your lymph nodes during cancer treatment. The lymph fluid isn’t able to drain properly and the fluid buildup causes swelling. When the swelling occurs in the arm, it can affect the fingers and cause pruney fingers. Other symptoms of lymphedema include:

  • a sensation of tightness or heaviness
  • aches or discomfort
  • decreased range of motion
  • hard or thick skin (fibrosis)
  • frequent infections

Learn more about lymphedema.

Lupus

Systematic lupus erythematosus, often referred to as “lupus,” is an autoimmune disease in which the immune system unnecessarily attacks itself, causing chronic inflammation.

When the inflammation occurs in the fingers, they might become red and pruney due to the swollen glands. Other symptoms of lupus vary widely, and many are present in other conditions not associated with lupus. Symptoms can include:

  • fatigue
  • rash
  • hair loss
  • fever
  • kidney problems
  • gastrointestinal problems
  • dry eyes and mouth

Learn more about lupus.

Vitamin B-12 deficiency

Vitamin B-12 is just one of the vitamins that can keep you from developing pruney fingers. It is responsible for blood formation, nerve function, cell metabolism, and DNA production. Most people aren’t deficient in this vitamin because it can be stored in the body for several years.

However, if you are vegan or vegetarian, you have an increased chance of being deficient in vitamin B-12, since it is present in meat, poultry, fish, and dairy. Symptoms of vitamin B-12 deficiency include:

  • anemia
  • poor balance
  • fatigue
  • shortness of breath
  • tingly feet
  • memory loss

Learn more about vitamin B-12 deficiency.

The cause of your pruney fingers will determine what type of treatment you need. While pruney fingers caused by water immersion is a harmless condition and will quickly fade, and drinking more water often cures dehydration, other causes may require medical treatment.

Treating diabetes

Depending on the type of diabetes you have, your doctor may recommend monitoring your blood sugar, eating a healthy diet, and using insulin therapy or oral medications.

Treating a thyroid disorder

For hyperthyroidism, your treatment might include medications, radioactive iodine, surgery, or beta blockers.

Hypothyroidism is usually treated with thyroid hormone medication in pill form and is usually taken for your entire life.

Treating lymphedema

Treatment for this condition can involve exercises, massage, compression garments, pneumatic compression, wrapping of the arm, and complete decongestive therapy (CDT).

There is no cure for lymphedema, only a managing of symptoms to reduce swelling and control pain.

Treating lupus

Depending on the severity of the lupus, your doctor may suggest taking anti-inflammatory drugs (NSAIDs), corticosteroids, or immunosuppressants.

Management also includes:

  • avoiding excessive sunlight
  • getting plenty of rest
  • engaging in moderate exercise
  • avoiding smoking and secondhand smoke

Treating a vitamin B-12 deficiency

Your doctor may advise you to take a vitamin B-12 supplement, as an injection, a pill dissolved under your tongue, or as a nasal spray.

Most of us will experience pruney fingers at some point in our lives, whether we are having fun in a pool or taking an extra-long bath.

When you get pruney fingers without being immersed in water, this otherwise harmless side effect could be pointing to something more serious.

If you develop pruney fingers without water and they don’t go away, make an appointment with your doctor. Make a list for your doctor of any co-occurring symptoms. They’ll be able to determine the cause of your pruney fingers and get you the treatment you need.