Technically, unless their PMTA is approved, all e-cigarettes (and other new nicotine products) are being marketed and sold illegally in the United States
Most people then switch to a lower nicotine level like 6 mg/ml, but this notably reduces the throat hit from the nicotine
Kohler, Lords of the Fly , chapter 5 "Abbie Lathrop, the "Mouse Woman of Granby": Rodent Fancier and Accidental Genetics Pioneer"
No Smoking: The Ethical Issues (University of Chicago Press, 1989)
A customs document from 1627 states that snus was brought to Sweden from Porvoo in Finland for the first time
However, if you are prescribed prednisone for a chronic condition, check with your doctor before using Benadryl regularly, as frequent use may mask symptoms that need medical attention