Its use among physicians in the US can be traced to the late 1800s and early 1900s. The earliest research comes from Dr. Gerhard Madaus of Germany, who came to the US in search of echinacea in 1938. Since then, numerous studies have been conducted, both in Germany and the United States. Roots, stems and flowering herbs of these three species have all been used in different combinations by different studies. Methods of preparing and administering the herb have been inconsistent, ranging from injections to crushed powder to tinctures and tablets.
Dosages also vary widely.
Measuring the duration and severity of symptoms can be very subjective and nearly impossible to quantify without bias. There also is no way to test whether a patient actually has a virus and whether that virus is susceptible to echinacea . In spite of these difficulties, most scientists agree that there is some truth to all the hype about echinacea .