Sulfur Spring's mineral content, and its lack of sugar, not only makes it poorly absorbable by the gut but also makes it capable of inducing diarrhea if taken in ample quantities. But if diarrhea is the effect of a dose of this particular mineral water, why would Lewis treat his very ill, dehydrated patient with a purgative, which would cause further fluid losses?
The answer to this question is a key to understanding why Lewis referred to "the virtues" of the water he "resolved to try on the Indian woman." His selection of therapy was not a random choice. He certainly was not aware of the physiologic derangements of dehydration, infection or shock, all concepts that awaited scores of years to be tested and understood. Rather, Lewis accepted the rudiments of contemporary theories of medicine. In that era it was believed illnesses were caused by inflammatory substances in the body. Treatments were directed at ridding the body of these morbid substances. Commonly used depletive therapies included bleeding, vomiting, bowel purging, blistering and sweating.
Prior to the administration of the Sulfur Springs water, Clark had already bled Sacagawea three times, sweated her with potassium nitrate, treated her fever with Peruvian barks, and purged her system with a "doste of Salts."
At the time of a serious illness, Lewis's turning to a potential gentle purgative effect of natural Sulfur Springs water was entirely consistent with accepted understanding of diseases and treatments. It also demonstrated his resourcefulness. He was personally familiar with the laxative effects of mineral salts and often took a dose of his favorite remedy, Glauber's salts, when beset by abdominal discomfort or diarrhea.
If, at best, the Sulfur Springs water had only a mild laxative effect, then what cured Sacagawea? More than likely, her recovery was not due to any of the treatments administered by the captains, including the water from Sulfur Springs. Ironically, Sacagawea's ingestion of Sulfur Spring water merely coincided with her own immune system's ultimate clearing of the self-limited infection. As anticlimactic as this explanation seems, the episode demonstrates a recurring theme in the medical care the captains gave the members of the Corps of Discovery. They used very pragmatic approaches based on what they understood about illnesses, and their patients seemed to recover afterwards. It is a tribute more to the robustness of Sacagawea and the men of the Corps than to the medicines the Captains dispensed.
Funded in part by a grant from the Montana Committee for the Humanities