How venomous are the snakes compared with Germany, Austria and Switzerland?

Comparable, and in one respect surprising: the nose-horned viper, the larger of the two species, also lives in Austria, with more occurrence records there than in Bulgaria. The common adder is recorded in Germany, Austria and Switzerland, and far less often in Bulgaria. Switzerland even has a third species, the asp viper, which does not occur here. The same rule applies as at home: snakes retreat as soon as they notice a person, and after a bite you see a doctor.