https://en.wikipedia.org/wiki/Santonin
Santonin was an agent which (compared to more modern anthelminthic drugs) was very complicated to use and entailed rather serious risk to the patient. Nearly every formulary and herbal which lists santonin or santonin-containing plants lists the real risk of yellow vision and of fatal reactions; even small doses of santonin cause disturbances of vision, usually yellow vision or perhaps green (xanthopsia or chromatopsia). Even the Encyclopædia Britannica noted:
...These effects usually pass off in a few days. Large doses, however, produce toxic effects, aphasia, muscular tremors and epileptiform convulsions, and the disturbances of vision may go on to total blindness.
More typical is the warning given regarding side effects of santonin in King's American Dispensatory:
Santonin is an active agent, and, in improper doses, is capable of producing serious symptoms, and even death. As small a dose as 2 grains is said to have killed a weakly child of 5 years, and 5 grains produced death in about 1/2 hour in a child of the same age. Among the toxic effects may be mentioned gastric pain, pallor and coldness of the surface, followed by heat and injection of the head, tremors, dizziness, pupillary dilatation, twitching of the eyes, stertor, copious sweating, hematuria, convulsive movements, tetanic cramps stupor, and insensibility. Occasionally symptoms resembling cholera morbus have been produced, and in all cases the urine presents a characteristic yellowish or greenish-yellow hue. We have observed convulsions caused by the administration of "worm lozenges." Death from santonin is due to respiratory paralysis, and post-mortem examination revealed in one instance a contracted and empty right ventricle, and about an ounce of liquid, black blood in the left heart, an inflamed duodenum, and inflamed patches in the stomach (Kilner). . . . Santonin often produces a singular effect upon the vision, causing surrounding objects to appear discolored, as if they were yellow or green, and occasionally blue or red; it also imparts a yellow or green color to the urine, and a reddish-purple color if that fluid be alkaline. Prof. Giovanni was led to believe that the apparent yellow color of objects observed by the eye, when under the influence of santonin, did not depend upon an elective action on the optic nerves, but rather to the yellow color which the drug itself takes when exposed to the air. Santonin colored by the air does not produce this effect, which only follows the white article. The air gives the yellow color to santonin, to passed urine containing it, and to the serum of the blood when drawn from a vein, and, according to Giovanni, it is owing to its direct action upon the aqueous humor, where it is carried by absorption, that objects present this color. The view now held, however, is that of Rose, that the alkaline serum dissolves the santonin, which then acts upon the perspective centers of the brain, producing the chromatopsia or xanthopsia.
Yes... "wisdom from above"!!