"It is possible to drink too much water when trying to hydrate?” Yes, given a great deal of excess it is possible to over hydrate with water, bringing on hyponatremia or “water intoxication,” a condition of abnormally low sodium in the blood. While it can be precipitated by a number of diseases and medications, in the otherwise healthy individual it is caused by taking in too much water over too short a period of time and results in free water shifting from blood vessels to the cells outside. The expansion that results in these cells is generally well tolerated as long as there is space within which to enlarge. However, given the rigid confines of the skull, when brain tissue swells it has little room within which to grow and can be very serious. In the absence of skillful treatment, it can be fatal. The signs and symptoms of water intoxication can include nausea, headache, muscle weakness, apathy, fatigue, confusion, convulsions and coma. This possible presentation is of great consequence to the diver as these features are also seen in decompression illness (DCI), the treatment of which is very different. A misdiagnosis could mean death. While hyponatremia may be more common than has generally been thought, it appears to remain a very low probability event. In adults it is most frequently seen in association with high–endurance activities like marathons, strenuous hiking or cycling and long military marches where there is excessive water intake within an inadequately long time span. The healthy human body is able to excrete and tolerate a very large quantity of water without adverse affect provided it is imbibed at anything approaching a sensible rate. Adding in the dehydrating effect of diving due to several mechanisms (e.g., elevated ambient temperatures, immersion diuresis, breathing extremely dry air), bringing on hyponatremia during active scuba would seem quite a feat. As dehydration is prominently associated with DCS, not surprisingly divers endeavor to drink lots of liquids. While this is a good thing, it must be done with some degree of moderation. And, it's a wise idea to balance water intake with sports drinks formulated to match the body's natural levels of potassium, citrate and sodium chloride. Be aware that many sports drinks actually contain very little salt, so be sure to read and understand the product labeling. If you are properly hydrated, you will not be thirsty, have dry mouth or sticky saliva and will urinate regularly and copiously with output of a pale straw color. © Doc Vikingo 2005 Back to Doc Vikingo's Divers Resource Page Contact Doc Vikingo Back to Awoosh Main Directory