Shelter Health

Hypernatremia and Activated Charcoal

Activated charcoal can be a very powerful tool in a toxicology treatment protocol, but it has some downsides. Some aren’t necessarily too serious – vomiting, dark stool, diarrhea – but others, like aspiration and hypernatremia, are more worrying.

We’ll focus here on hypernatremia from charcoal, answering some of the most common questions.

  • Why does it happen? It appears that charcoal pulls fluid from the body into the gastrointestinal tract, resulting in an elevation of the serum sodium.
  • Does sorbitol have anything to do with it? As a cathartic it is likely that it does, however we have seen cases of hypernatremia develop when charcoal without sorbitol is used.
  • Does the patient’s size matter? While it may be more likely for our smaller patients to develop hypernatremia, we have seen it in all sizes of dogs – large and small.
  • Does it matter how much I give? Definitely. Large doses do put animals at higher risk for developing hypernatremia, as well as repeating doses of charcoal.
  • Can the toxin play a part in causing the hypernatremia? Yes. Toxins that are osmotically active (pulling fluid towards them) such as paintballs or large ingestions of sugar, candy, or chocolate will increase the risk for hypernatremia. Other toxins that can affect the sodium, such as diuretics, can increase risk as well. Food items with high sodium content (salt, baking soda) would also increase the risk.
  • Does it matter if my patient is dehydrated? Yes. This can increase the risk for the hypernatremia to occur.
  • When are signs visible? Generally signs are seen within four hours of charcoal administration.
  • What does it look like? Common signs are ataxia, tremors and seizures (particularly those that don’t respond well to diazepam).
  • How can you tell it’s hypernatremia? This can be a tricky one, since there are a lot of toxins, like Bromethalin, that cause CNS signs that look like hypernatremia or vice versa. We advise checking sodium prior to giving charcoal for a baseline – or if the pet is already hypernatremic – and again within four hours if you have signs that are suspicious of hypernatremia. Remember sodium does not always have to be out of the normal range to cause signs; even a five-point jump is concerning.
  • Are all species affected? The cases we see are mainly in canines, however it is possible in cats and other species as well.


Read more about using charcoal safely here. 

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