(NewsNation) — Jacqui Berlinn used to hide her son Corey’s drug addiction out of shame.

But now, she’s speaking out, especially as fentanyl-related deaths are on the rise.

Recently, the Drug Enforcement Administration sent a letter to its federal, state and local law enforcement partners, warning of a nationwide spike in fentanyl-related mass overdose deaths. These events, which the DEA characterizes as three or more overdoses happening close in time and in the same location, have happened in at least seven cities in recent months, according to a news release, resulting in 58 overdoses and 29 deaths.

Corey has been addicted to drugs, living on the street on and off, for about 10 years, Berlinn said. He was initially doing heroin, but then he was introduced to fentanyl.

“A couple years ago, about 18 months to two years ago, a dealer put fentanyl into his heroin unbeknownst to him and got him addicted to fentanyl,” Berlinn said on “NewsNation Prime.” “Heroin is a scary addiction. But fentanyl is 100 times scarier.”

Berlinn has seen Corey, who lives in San Francisco, deteriorate more in 18 months on fentanyl than he did in years and years on heroin, she said.

“It’s an extremely dangerous and debilitating drug,” Berlinn said. “He’s gone to losing many of his teeth to not being able to stand up completely straight.”

The “fentanyl fold,” as Berlinn called it, has caused her son, 31, to walk like an old man, she said.

“Sometimes the addicts will use the fentanyl and it will immediately kind of make them pass out and they pass out standing up or sitting up and it kind of makes them lean over,” she said.

Corey and Berlinn spoke on Sunday. He tries to call his mom every couple of weeks.

Berlinn said her son will be the first to admit he’s made a few terrible mistakes and blames himself completely.

“I do believe … he’s very sick,” she said. “Addiction is an illness, and he did not expect this. He did not want this. And he’s struggling to break free of it.”

At first, Berlinn didn’t talk about her son’s addiction. But her son assured her: It wasn’t anything Berlinn or his dad did to cause it.

“Here’s my one child out of six, who was a little more daring, a little more experimental,” Berlinn said. “He always kind of liked to have fun and so he tried this. And it ended up causing him to get addicted.”

It’s a mistake Berlinn said she thinks other kids are making, too, at a high cost. On his last call to his mom, Corey described seeing more people coming into the city to buy fentanyl.

“Fentanyl is incredibly dangerous,” Berlinn said.