Thousands of people around the world die every day from overdoses involving opioids such as fentanyl. Drugs that target opioid receptors sometimes have severe side effects. An international team of researchers has taken a closer look at the molecular mechanisms of these active substances. The research, carried out by Dr Matthias Elgeti, a biophysicist at Leipzig University, in collaboration with research groups from the US and China, has now been published in the journal Nature.