Fentanyl has become the world's deadliest opioid, responsible for close to 80,000 deaths a year in the US alone. The drug is 10 to 20 times more potent than heroin and is widely used in medical settings for pain reduction and sedation. Fentanyl is so hardy that even small amounts can lead to fatal overdose. The drug has also become a political issue, with Democrats seen as soft on prevention and President Donald Trump taking a tougher line. The writer shares their personal experience of receiving fentanyl during a colonoscopy and the energetic days that followed.