Furthermore, the relationship, if any, of this activity to the drug's purported ability to dry up the milk of nursing mothers is unclear. All of these scientific studies would obviously confirm many of the uses of sage as a popular household remedy if it were not for an extensive investigation conducted in 1949 by H.B.J. van Rijn which cast doubt, or at least raised a real question, concerning them. Using small animals, he was unable to demonstrate any anhidrotic effect in sage, nor could he detect effects on blood pressure and respiration . Details of the poisonous character of thujone are provided in information about wormwood. Basically, it can cause both mental and physical deterioration when consumed in small amounts over a long period of time.
Large doses can result in convulsions and loss of consciousness.
We know that the plants containing it are not innocuous, so if van Rijn was right in this part of his study, he may also have been correct in his conclusion that sage, aside from its astringent action, is without medicinal value. This use appears justifiable. However, they also allow its internal use for digestive upsets and excessive perspiration. On the basis of published data, these latter uses seem inappropriate because of the known toxicity and lack of proven effectiveness of the herb in such cases. But after all, herbs should be used to improve health, not to diminish it.