This is a term traditionally used to indicate anything in the diet or regimen that may disturb or extinguish the action of a homeopathic remedy. Samuel Hahnemann wrote an extensive footnote in his central work, The Organon of Medicine, in which he enumerated a large number of things he believed fell into this category. It includes many foods, drinks and spices such as salad, pork, ice cream, celery, coffee and most spices which are in common use today, though they no doubt were rarities in early 19th century German cuisine. Also included were things life wearing woolen clothes next to the skin, reading in a horizontal position, keeping late hours, mental and physical overexertion as well as a sedentary lifestyle.
Although not mentioned in this particular passage, it was a matter of course that other medications, be they allopathic, herbal or homeopathic (other than the one prescribed) be avoided