Hyponatremia Symptoms and First Aid

Hyponatremia is Also Commonly Known as Water Intoxication

Conivaptan hyponatremia drug molecule. Credit: Molekuul/Science Photo Library / Getty Images

Hyponatremia is also commonly known as water intoxication. During hyponatremia, the water and sodium that are lost to perspiration are replaced in return only with water, which leaves the body low in sodium. While hyponatremia has always been a major concern during military training, today's growing occurrences of hyponatremia are often the direct result of athletes drinking lots of water during endurance sports.

Hyponatremia can also occur as a result of binge alcohol drinking.

Heat Exhaustion or Hyponatremia?

Participants in marathons and other endurance events across the nation have become confused and even collapsed during competition due to hyponatremia. However, many more participants in these very events have also become confused and collapsed from dehydrationheat exhaustion, or heat stroke. It is often difficult to initially tell the difference between heat exhaustion and hyponatremia based on the symptoms.

The need to remain hydrated during periods of exertion, particularly in hot climates, is well-known, but it also makes it difficult to recognize hyponatremia symptoms. Severe dehydration and heat exhaustion look very similar to hyponatremia and, like hyponatremia, are more common in hot weather during exercise.

Symptoms of Hyponatremia

Hyponatremia has a variety of potential symptoms. These symptoms include:

  • weakness
  • dizziness
  • nausea
  • muscle cramps
  • slurred speech
  • confusion
  • loss of consciousness
  • seizures in severe cases

There is very little that can be done outside of an immediate trip to the hospital for hyponatremia, so differentiating between dehydration and hyponatremia is the most important part of hyponatremia first aid.

The symptoms are similar enough that a good assessment must include interviewing the victim and witnesses to determine is the victim was drinking water or not. 

Hyponatremia First Aid

Victims with slurred speech, confusion, severe weakness, or loss of consciousness need medical attention immediately. Call 911 for these victims as quickly as possible, regardless of the cause.

Heat exhaustion and dehydration can look very much like hyponatremia and are much more common. Heat stroke has a distinct set of symptoms and is a serious emergency.

Determine if the victim has been staying hydrated. If witnesses can confirm the victim has been drinking at least a pint of fluid per hour during exercise, consider the possibility of hyponatremia. In cases of rapid massive water intake -- such as college fraternity initiation -- consider the possibility of hyponatremia.

Victims of hyponatremia need salt in order to even out the body’s sodium levels. In minor cases -- usually, just when nausea is present -- before cramps, dizziness or confusion occur, victims may feel better immediately after salty food intake.

Be very careful not to treat dehydration as hyponatremia and suggest salty foods when the victim really needs fluid. Assume any victim complaining of thirst is dehydrated.

Avoid NSAIDs like ibuprofen, aspirin, or naprosyn when concerned about hyponatremia. These pain relievers may make symptoms worse.


Almond, Christopher S.D., et al. "Hyponatremia among Runners in the Boston Marathon." New England Journal of Medicine. 14 APR 2005.

Vrijens, D. M. J., and N. J. Rehrer. "Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat." J Appl Physiol. Vol. 86, Issue 6, 1847-1851, June 1999.

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