Most young people of today associate the word "dropsy" with the fumbling of their grandparents. However, throughout history, dropsy was a widespread illness that caused peoples bodies to swell into grotesque shapes, squeezed their lungs, and finally brought slow, but inexorable death. As the disease progressed, a watery liquid filtered into every available space and expanded like a balloon. Sometimes the liquid in the amount of quarts or even gallons made arms and legs swell so that they became immovable. At times it poured into the abdomen to form a tremendous paunch. And worse, it could waterlog the lung cavity and thereby made it impossible for the victim to breathe unless he sat upright 24/7.
The disease used to be called "hydrops," and following tuberculosis it was one of the chief causes of death in the United States. Historically, it plagued mankind for ten thousand years. Today, the condition is most commonly referred to as edema, described as “an abnormal accumulation of fluid in the tissues or in a body cavity.” It was finally discovered that it was caused by the consumption of mustard oil adulterated with oil of prickly poppy. "Prickly poppy" contains alkaloids with active toxins. The prickly poppy grows as a wild weed that produces a yellow flower and its seeds are blackish brown with a wrinkled surface. Contrary to the poppy, mustard seeds have a smooth round surface. Mustard seeds are harvested earlier than that of the prickly poppy and hence there is little chance of accidental mixing of the two together.
However, if the two are inadvertently mixed the condition known as “dropsy” is produced. It is reported that 1% adulteration of mustard oil by the prickly poppy’s argemone oil is sufficient to cause the clinical disease. All age groups were affected by the disease except for breast fed infants. Dropsy mainly affects the lower socioeconomic groups because of their pattern of purchasing mustard oil. They generally would buy the oil in small amounts and in a loose unpackaged form that could become easily contaminated.

A dropsy victim in the 19th and 20th Century

Relief of dropsy by drainage 1700

A "prickly poppy" flower in Texas. The plant ranges from
east Texas to northern Arkansas and southern Missouri.