Hypertonic dehydration occurs when there’s an imbalance of water and salt in your body.

Losing too much water while keeping too much salt in the fluid outside your cells causes hypertonic dehydration. Some causes of this include:

Hypertonic dehydration differs from hypotonic dehydration, which is due to too little salt in the body. Isotonic dehydration occurs when you lose equal amounts of water and salt.

When your dehydration isn’t severe, you may not notice any symptoms. However, the worse it gets, the more symptoms you’ll show.

Symptoms of hypertonic dehydration include:

  • thirst, sometimes severe
  • very dry mouth
  • tiredness
  • restlessness
  • overactive reflexes
  • doughy skin texture
  • continuous muscle contractions
  • seizures
  • high body temperature

While the above relate to hypertonic dehydration, many of the same symptoms are present in standard dehydration. There are three levels of dehydration, each of which can have its own symptoms. When you have hypertonic dehydration, you may have some or all of these symptoms as well:

  • Mild dehydration can cause headache, weight loss, fatigue, thirst, dry skin, sunken eyes, and concentrated urine.
  • Moderate to severe dehydration can cause tiredness, confusion, muscle cramping, poor kidney function, little to no urine production, and fast heart rate.
  • Severe dehydration can lead to shock, weak pulse, bluish skin, very low blood pressure, lack of urine production, and in extreme cases, death.

Infants with moderate to severe dehydration or hypertonic dehydration may have:

  • crying without tears
  • fewer wet diapers
  • tiredness
  • sinking in the soft part of the skull
  • convulsions

Hypertonic dehydration is most common in infants, older adults, and those who are unconscious. The most common causes are diarrhea, high fever, and vomiting. These can lead to dehydration and a salt-fluid imbalance.

Newborns may also get the condition when they’re first learning how to nurse, or if they’re born early and are underweight. Additionally, infants can get intestinal disease from diarrhea and vomiting without being able to drink water.

Sometimes hypertonic dehydration is caused by diabetes insipidus or diabetes mellitus.

If your doctor thinks you might have hypertonic dehydration, they’ll note your signs and symptoms. They can confirm the condition by measuring serum sodium concentration. They might also look for:

While general dehydration can often be treated at home, hypertonic dehydration generally requires treatment by a doctor.

The most straightforward treatment for hypertonic dehydration is oral rehydration therapy. This fluid replacement contains a bit of sugar and salts. Even though too much salt causes hypertonic dehydration, salt is needed along with the water, or there’s a chance for swelling in the brain.

If you can’t tolerate an oral therapy, your doctor may recommend 0.9 percent saline intravenously. This treatment is meant to lower your serum sodium slowly.

If your hypertonic dehydration has lasted less than a day, you may be able to complete the treatment within 24 hours. For conditions that have lasted longer than a day, a treatment of two to three days may be best.

While in treatment, your doctor may monitor your weight, amount of urine, and serum electrolytes to make sure you’re receiving fluids at the right rate. Once your urination is back to normal, you may receive potassium in the rehydration solution to replace the urine you’ve lost or to maintain the fluid levels.

Hypertonic dehydration is treatable. Once the condition has been reversed, knowing the signs of dehydration can help you prevent it from happening again. If you believe you have chronic dehydration despite efforts to stay hydrated, talk to your doctor. They’ll be able to diagnose any underlying conditions.

It’s especially important for young children and older adults to drink enough fluids, even when they don’t feel thirsty. Catching dehydration early generally results in a full recovery.