Risk factors: Certain drugs. Medications that increase your risk of hyponatremia include thiazide diuretics as well as some antidepressants and pain medications. In addition, the recreational drug Ecstasy has been linked to fatal cases of hyponatremia. http://www.mayoclinic.org/diseases-conditions/hyponatremia/b...

While staying hydrated can reduce the risk of heat stroke associated with MDMA, the drug can also cause the body to retain water, so drinking too much can lead to a potentially fatal electrolyte imbalance. http://healthland.time.com/2013/09/03/concert-deaths-five-my...

More common, ecstasy has led to serious hyponatremia and hyponatremia-associated deaths. Hyponatremia in these cases is due to a "perfect storm" of ecstasy-induced effects on water balance. Ecstasy leads to secretion of arginine vasopressin as well as polydipsia as a result of its effects on the serotonergic nervous pathways. Compounding these effects are the ready availability of fluids and the recommendation to drink copiously at rave parties where ecstasy is used. The effects of ecstasy on the kidney as well as therapeutic measures for the treatment of ecstasy-induced hyponatremia are presented. http://www.ncbi.nlm.nih.gov/pubmed/18684895

Additional risk factor: Poorly thought out radio contests:

"A 28-year-old woman found dead hours after taking part in a radio station's water-drinking contest died of water intoxication, the coroner's office said Saturday" [1]

[1] http://articles.latimes.com/2007/jan/14/local/me-water14