Charities are warning of a "human catastrophe" as more people turn to drugs and alcohol to "cope" with the cost of living crisis.
New research, commissioned by The Forward Trust, revealed 32% of people said either they, or someone close to them, had relapsed into substance use over the past eight months.
Overall 2.1 million said they had increased alcohol use, while 61% of those said stress over rising prices was the most significant trigger.
Tom, 57, has been in recovery from heroin use for the past eight years.
He began taking drugs when he was 16 and told Sky News that anxiety over how to afford food and heating has made him vulnerable to a relapse.
"My health is going downhill because I do get really stressed out," Tom says.
"I couldn't cope with things, and I just didn't know how to escape it. That's why I started the drug abuse."
He adds: "If it weren't for my dog and my friend, helping me to get out of my mood swings, I'd have been dead by now, through either drug abuse or overdose."
Sian Reed-Collins, a recovery worker at charity Turning Point, said it was "scary" for people in recovery who used substances to "numb" stress.
"Unfortunately, things like the cost of living crisis mean people are going to go back to substance use," she told Sky News.
"It's a way of coping with this - helping with their stress levels, helping with their anxiety. And it's a scary time out there for people."
Last year, the government pledged nearly £800m in a landmark 10-year drug recovery strategy.
But with the autumn budget approaching and suggestions of economies to come, campaign groups are calling for that funding to be secure, as needs rise.
"This is a human catastrophe that we're facing and people need help," Matt Thomas, spokesperson for Forward Trust said.
"They need help urgently and they need help now because addiction is, at its worst, a killer condition."