In this article, Dr Adam Holland explains how small amounts of nitazenes, super-strength opioids, are increasingly being found in street drugs. Recent figures from the Office for National Statistics show that half the drug-related deaths in the last year involved an opioid, many of which are laboratory-made. Holland emphasises that even 'tiny amounts of some nitazenes can cause an overdose' and that the fentanyl crisis in the US may provide some insight into the trajectory of the UK's own growing opioid problem.