Causes of low sodium levels, or hyponatremia, include chronic or severe vomiting and diarrhea, drinking too much water, dehydration, and hormonal changes, explains Mayo Clinic. Drugs that cause this condition include MDMA, diuretics, and some antidepressants and pain medications. Heart, kidney or liver problems also sometimes cause low sodium levels.
Symptoms of hyponatremia include confusion, headache, nausea, vomiting and fatigue. In some cases patients experience seizures, muscles weakness, spasms and coma. Patients with sodium levels that drop over a long period of time experience moderate symptoms and complications. Sodium levels that drop rapidly potentially result in brain swelling, coma and death.