Blood poison was often used during the 1800’s and into the early 1900’s as a general wastebasket diagnosis to explain many common non-serious and serious conditions. Although blood poison, in those days, could mean the same thing as an infection of the blood introduced through a wound, it was just as often a way of saying “it’s in your blood.” there was little evidence to support these diagnoses.
Something being “in your blood” would seem easier to deal with than something that is not only in the circulating blood, but also in the lymphs and tissues. So, you can see the motivation for such a diagnosis: “It’s in your blood and we can easily get it out of your blood.”
However, at the same time, such blood poisoning was used to explain conditions that obviously manifested in the tissues. For example, the above advertisement for Dr. Brown’s Blood Poison cure claims that people with pimples, ulcers, spots on the skin, etc. often have blood poison, “the worst disease on Earth.” But…easy to cure!
There was little attempt to describe exactly what had “poisoned” the blood, yet this unknown infections or poisonous substance in the blood was easily cured by patent medicines. Such wastebaskets diagnosis still exist today, but were very prevelant during the 17th century. They were used as a ‘catch-all’ when no other specific problem could be found.
Just as today, when people diagnose themselves with adrenal fatigue or a a gluten sensitivity, people in the 1800’s would often diagnose themselves with “blood poisoning.” Anything that was painful and swollen would be deemed a case of blood poison and there were many home cures, usually poultices, claimed to take care of these cases in a few hours. These were of course, simply local reactions to a wound or something as simple as a splinter, which, as we all know, can be quite painful and red, but certainly not usually deadly.