Blue Vervain is said to be excellent in cases of colds and chest congestion. As an herbal expectorant, it helps to loosen and expel phlegm from the throat and chest. It is considered one of the best herbs to help alleviate the onset of a cold, especially with upper respiratory inflammation of the lungs. Moreover, Blue Vervain also acts as a sudorific, or agent that promotes sweating and thereby cools the body and reduces intermittent fevers, which also helps to relieve symptoms of colds. Sweating not only works to reduce fever, but it also acts to rid the body of toxins through the skin. At one time, the herb was frequently given to children to ease fevers and other minor ailments.

As an "alterative," Blue Vervain is believed to have a cleansing effect on the system that stimulates the efficient removal of waste products from the body. First, by encouraging sweat, it helps to remove toxins through the skin. Furthermore, as an herbal diuretic, Blue Vervain encourages the flow of urine and helps to quell infection and remove toxins and obstructions (including gravel from the bladder) through the increased urine. This is said to be helpful in cases of gout by promoting the flow and expulsion of uric acid.