Opioids are powerful pain-relieving drugs. They work on the synapses of neurones and among other things inhibit transmission of pain messages. They also have a sedative, cough-suppressant and respiratory-depressing effect. Opioids are used for example to treat severe pain in the case of operations or cancer. They have a high addiction potential and should therefore be used with caution. The indicator in the Swiss Atlas of Healthcare shows opioids dispensed by outpatient care providers. The indicator is limited to opioids (ATC code starting with ‘N02A’), which belong to narcotic-like medicines according to the Swissmedic definition.