Effects of echinacea on the frequency of upper respiratory tract symptoms: a randomized, double-blind, placebo-controlled trial

Abstract

Prophylactic treatment with commercially available E. purpurea capsules did not significantly alter the frequency of upper respiratory tract symptoms compared with placebo use.

Herbal Medicine for Cough: a Systematic Review and Meta-Analysis

“…We found 8 studies exploring the use of a varied range of solid and liquid Echinacea preparations in the treatment of cough symptoms for common cold or URTI [16,41,42,43,44,45,46,47]. A total of 1,130 patients were enrolled in these studies, with an average of 141 patients per study.…”

Echinacea for preventing and treating the common cold

“…Of these, 15 had been included in the previous version of the review (Barrett 2002; Brinkeborn 1999; Bräunig 1992; Dorn 1997; Galea 1996; Goel 2004; Goel 2005; Grimm 1999; Hoheisel 1997; Kim 2002a; Lindenmuth 2000; Melchart 1998; Schulten 2001; Taylor 2003; Yale 2004), two of the now included studies on induced colds had initially been excluded in the previous version of the review (Sperber 2004; Turner 2000) and seven studies have been newly included (Barrett 2010; Hall 2007; Jawad 2012; O’Neill 2008; Tiralongo 2012; Turner 2005; Zhang 2003). One study (Taylor 2003) was in children, the other 23 in adults.…”

“…In four of these trials 431 healthy volunteers (Hall 2007) or persons being challenged by inoculation with rhinovirus (Sperber 2004; Turner 2000; Turner 2005) were treated over a shorter period (two to four weeks). Six trials including 1391 participants (Grimm 1999; Jawad 2012; Melchart 1998; O’Neill 2008; Tiralongo 2012; Zhang 2003) treated healthy volunteers over a longer period (6 to 16 weeks) for preventative purposes.…”

“…The 14 remaining Echinacea preparations were only used in one trial each: tinctures or extracts prepared from E. pallida root (Dorn 1997), E. angustifolia root (Melchart 1998) or E. angustifolia , without information on the plant parts used (Galea 1996); a dried plant preparation based on 50% E. angustifolia root, 25% E. purpurea root and 25% E. purpurea herb (Barrett 2002); a preparation based on E. purpurea root and E. angustofolia root , without information on extraction details (Barrett 2010); a tincture from 80% E. purpure a herb and 20% E. angustifoli a root (Kim 2002a); a preparation based on an extract of E. purpurea root and E. angustofolia root (extraction details not reported) (Tiralongo 2012); a 4% phenolic extract of E. purpurea and E. angustofolia (Turner 2000); three preparations based on E. angustofolia root using three different extraction methods (20% alcohol; 60% alcohol and CO 2 ) (Turner 2005); two kinds of E. purpurea capsules (parts and extraction details not reported (Hall 2007; O’Neill 2008); and a tea preparation based on dry extracts from the aerial parts of E. purpurea and E. angustifolia (Lindenmuth 2000). …”

“…We rated five more trials as low risk of bias, having an unclear risk of bias in only one category. We rated eight trials as having a high risk of bias (Bräunig 1992; Dorn 1997; Galea 1996; Hoheisel 1997; Jawad 2012; Lindenmuth 2000; O’Neill 2008; Zhang 2003) and six as having an unclear risk of bias.…”