Safety and Tolerability Study of Ragweed SLIT Tablets

Inclusion Criteria: * written consent * male or female subjects from 18 yo 60 years old and in general good health * for women of child bearing potential: negative urine pregnancy test and use of medically effective contraceptive method * symptoms of ragweed pollen induced allergic rhinitis for at least the last 2 years * sensitization to ragweed pollen as demonstrated with positive skin prick test to ragweed pollen and specific IgE level (ragweed pollen) \> 0.70 kU/l at screening * FEV1 at least of 80% of predicted value at screening Exclusion Criteria: * past or current disease which, as judged by the investigator, may affect the outcome of this study * history of life-threatening asthma * asthma requiring daily treatment (whatever the pharmaceutical class) * pregnant or lactating women * subjects who previously received desensitisation treatment to ragweed pollen and/or other Asteraceae or who plan to start desensitisation treatment during this study * symptoms during the treatment phase due to a sensitivity to a second allergen * subjects treated with ongoing immunotherapy with another allergen