Most people consider the Cockapoo hypoallergenic. This is one reason he is such as popular mixed breed.
Cockapoos shed less than the Cocker Spaniel parent and trigger fewer allergies. But, they are not hypoallergenic. Studies suggest that allergens deposited as saliva on the coat trigger most allergies. Not cast off hair, thus no dog is 100% hypoallergenic. As the dog licks and self-grooms, he deposits protein flakes in the coat as saliva.
Before buying a Cockapoo, spend some time with him to gauge your allergic response. There is no guarantee that that dog will not trigger allergic reactions.