Bee with propolis load
Biene sammelt Propolis

Bees gather resin from the buds trees and transform it in the bee hive into propolis. They use it as a sealing cement to protect their hive against draught. Propolis is used as a natural medicine. It is the most powerful natural antibiotic.Propolis, as a natural product, has a composition which varies considerably depending on its origin. That is why there are no definite quality criteria.

Propolis is a drug. Drugs are specified in the Swiss Drug Directive. However propolis is not described in the Swiss pharmacopoe, as there are no specific quality criteria. 

Alles über Propolis (German (PDF, 150 kB, 14.09.2016) and Italian (PDF, 90 kB, 14.09.2016)) Harvest, composition and quality of propolis
S. Bogdanov (1999)