A study for health insurers AOK showed that while alcohol and smoking are the main cause for sick leave, more workers are also taking performance-enhancing pills.

Five percent of people insured by AOK admitted to taking drugs such as amphetamines while at work to improve their performance and cope with stress. For the under 30s the figure rose to 12 percent.

The number of days lost to sick leave through the pills has quadrupled since 2002. Helmut Schröder, who presented the study in Berlin on Thursday, spoke of a “clear trend”.

And the report warned that the addictiveness as well as the physical and psychological damage caused by the stimulants was being underestimated by young people.

Drug addiction is also having a knock-on effect on the economy. Uwe Deh from AOK said that alcohol and smoking addictions cost the German economy €60.25 billion a year. He said that the number of sick days lost to addictions had increased by 17 percent in the last ten years from 2.07 million in 2002 to 2.42 million in 2012.

Alcohol and smoking were the main causes of lost days, with 5.3 percent of those asked, admitting to drinking every day in the last week. Experts warned that dangers of addiction increased by drinking daily.

The report found that among those insured with AOK, one million working days were lost last year to alcohol, but the authors said that this was only the “tip of the iceberg” as the health impacts of drug addiction are normally diagnosed as other illness.