PURETHAL Birch RUSH Study

This study investigates the safety of two up-dosing regimen. The safety of PURETHAL Birch will be evaluated in a rush regimen (maximum dose reached in 3 injections during 3 weeks) compared to the conventional regimen (maximum dose reached in 6 injections during 6 weeks). The primary endpoint of the sudy is the comparison of the proportions of the patients who have successfully reached the maintenance dose between the two treatment regimes. A similar previous study with PURETHAL Grasses has shown that the rush up-dosing scheme is as safe as the conventional up-dosing regime. Therefore it is expected that up-dosing with PURETHAL Birch according to the rush regimen is as safe as using the conventional regimen.