This is a comparative, conceptual, randomized clinical study to investigate newly developed over basic Echinacea formulations for the treatment of acute symptoms of respiratory tract infections. 400 adults will be recruited, of which approximately 300 will develop a common cold or a influenza-like infection. Two newly developed and two existing Echinacea formulations (solid/liquid) will be randomly dispensed at inclusion for treatment of maximal 3 infections. Treatment starts at first signs of infection and lasts for a maximum of 10 days or until symptom resolution. Nasopharynx samples will be collected for analysis of common viral respiratory agents throughout treatment. Safety and efficacy variables will be assessed.

The monocentre trial compares two newly developed pharmaceutical forms of Echinacea (extract from Echinacea purpurea Herba and Radix; lozenges or spray) with two basic and authorised pharmaceutical forms (tablets or drops; comparator groups) for the treatment of acute symptoms of the common cold and/or influenza-like illness (ILI) in adults. Trial subjects are preventatively screened and included in the study (n = 400). If they show acute symptoms of a common cold or ILI during the study period, they are instructed to call the study centre to have confirmed the indication for treatment and begin with the treatment, they are randomized to (1:1:1:1 randomization into one of four groups). The primary endpoint is the time until remission of respiratory symptoms with the new pharmaceutical forms compared to the basic forms during the first episode. Secondary endpoints include remission of all treated episodes (max. 3 episodes), remission times comparison between different pharmaceutical forms (e.g. lozenges vs. spray, lozenges vs. drops etc), reduction of viral load on day 5 and 9 compared to day 1 of treatment (nasopharyngeal swabs), differences in safety (blood parameters before and during treatment), differences in number of adverse events, tolerance and efficacy assessed by the patients.

Inclusion Criteria:

• At least 18 years old
• Signed Informed Consent

Exclusion Criteria:

• Younger than 18 years
• Participation in another clinical study in the past 30 days
• Permanent intake of antimicrobial, antiviral, immune suppressive substances
• Surgical intervention in the 3 months prior to inclusion or planned surgery during period of observation
• Known diabetes melitus
• Known and treated atopy or asthma bronchiale
• Cystic fibrosis, bronchopulmonale dysplasia, COPD
• Known diseases of the immune system, degenerative illnesses (e.g. auto-immune disorders like AIDS or leukemia, myeloma)
• Known metabolic or resorptive disorders
• Known chronic liver diseases (chronic hepatitis, liver cirrhosis)
• Known chronic kidney insufficiency
• Serious health issues (reduced health status, autoimmune illness, tumorous illness)
• Known allergy to plants of compositae family (camomille, dandelion) or to any substances of the investigational product
• At inclusion known pregnancy or planned pregnancy during period of investigation (required: active contraception for women of childbearing year)