KNOXVILLE, Tenn (WVLT) -- We've been told too much salt is bad for our health- but is there such a thing as too little? Dr. Rebecca Jackson M.D., of Concord Summit Medical Group says, "Low sodium can be harmful , but usually not because you don't get enough in your diet. People who exercise and lose an excessive amount of sweat, and just hydrate with plain water, their sodium can go to low."

That's why she recommends people exercising hydrate with a sports drink that contains electrolytes.

But people can lose sodium other ways she says, "Hormonal problems such as thyroid, and other problems can cause low sodium like medicines. If you started on a new medicine, like a water pill, it's a diuretic, gets rid of excess sodium.

Doctor Jackson says it can be serious if not treated, "The symptoms are related to what's going on in the head, because a lot of what's happening is brain swells a little bit- headache being tired, nauseated, vomiting and after that feeling lethargic, tired, seizures and you can end up in a coma, or death."

That's why it is so important to talk to your doctor, if you have any of these symptoms.