Drugs & Alcohol—including medicines prescribed by a doctor or available from a pharmacy—can affect a person’s ability to work safely. All workers have a duty to take reasonable care for their own health and safety and ensure they don’t adversely affect that of others. This means they must be fit and well enough to do their job, not be under the influence of alcohol or drugs, or use alcohol or illegal drugs while at work. In some jobs such as road and rail transport, maritime and mining occupations, the law sets down a legal blood alcohol level and may prohibit a worker from being affected by any drugs—legal or illegal. In some instances prescribed medication can affect the worker and appear to be under the influence, take care when approaching the worker, request evidence and or a certificate from their general practitioner before allowing them to return to current work duties.

Click Link below for more information

http://www.safework.nsw.gov.au/drugs & alcohol workplace guide