Rapper Coolio died from the effects of a fentanyl overdose, a US coroner has ruled.
The drug causes tens of thousands of deaths in the US each year. But what is the drug, and what makes it so dangerous?
What is fentanyl?
Fentanyl is a synthetic opioid that is 50 times more powerful than heroin.
As a prescription drug, it is used to treat severe pain, similarly to morphine.
The fentanyl that is used illegally is most often made in labs and sold as a powder or pill.
What makes it so dangerous?
Its strength, for starters. Because it is so potent, the difference between a dose that can kill and one that won't is thin.
Fentanyl suppresses breathing at a much lower dose than other opioids.
Drug dealers also mix fentanyl - a cheaper drug - with heroin, cocaine, MDMA and methamphetamine to increase their profits.
Without knowing their drug has been cut with fentanyl, a person might accidentally take too much.
What are the effects of fentanyl?
Fentanyl can provide pain relief and create feelings of extreme happiness.
It can also cause nausea, confusion and sleepiness, problems breathing and unconsciousness.
What happens when someone overdoses?
Overdosing on fentanyl causes a person's breathing to slow or stop, limiting the amount of oxygen that reaches the brain.
This can lead to a coma, permanent brain damage, or even death.
An overdose can be treated with naloxone, a medicated nasal spray, which restores normal breathing.
How many people die of fentanyl overdoses each year?
In 2021, more than 70,000 Americans died from a fentanyl overdose, and almost 58,000 in 2020, according to the Centre for Disease Control (CDC).
More than 150 people a day in the US die from overdoses related to synthetic opioids like fentanyl.
Fentanyl is less prevalent in the UK and that's reflected in the numbers: 58 people died from known fentanyl poisoning in 2021. The highest number of known fentanyl deaths was recorded in 2017, when 75 people died from the drug.
However, there were 4,859 deaths related to drug poisoning overall in 2021, a 6.4% increase from 2020, and half of those involved an opiate.