CHICAGO — In the basement of the Mustard Seed, a red brick building in Chicago’s Old Town neighborhood that hosts dozens of Alcoholics Anonymous meetings each week, a handful of people gathered on a recent night to discuss a different addiction.

They were members of Marijuana Anonymous, a rapidly expanding 12-step organization that serves those struggling with a drug that is now legal in Illinois and 10 other states, and that many people view as innocuous.

That perception, some meeting attendees said, even extends to fellow drug users.

“When you’re in rehab for weed, you don’t say you’re in rehab for weed,” said Robb, a 30-year-old who lives in Chicago. “Half the people will laugh you out of the room.”

But treatment specialists say marijuana’s addictive potential is well-established. About 1 in 10 people who use the drug end up with the condition known as cannabis use disorder, meaning they continue to use compulsively even when it messes up their lives.

“It’s a lot like the other addictions,” said Michael Mahoney of Hazelden Betty Ford, a treatment center on Chicago’s Near North Side. “People want to stop using and can’t. They have to use in greater quantities to get the same effect or just have a feeling of normalcy. Along the way, problems emerge.”

The Chicago Tribune spoke with people in recovery from marijuana addiction about those problems, the complexities of treatment and the reluctance of others to recognize the seriousness of the habit (as is customary for participants in 12-step programs, they asked to be identified only by their first names or no name at all).

“Everyone I’ve told has been dumbfounded that it became an addiction,” said Shelby, a 36-year-old woman from Chicago. “It’s hard for them to grasp that marijuana is addictive, and also that I used every day for the most part and no one knew. That’s how secretive you can be, how good you can get at functioning on weed.”

Shelby said she started smoking marijuana at 14 — the odds of developing cannabis use disorder are 1 in 6 for people who first indulge when they’re younger than 18 — but it didn’t really become an obsession until she moved to California as an adult.

There, she said, the state’s liberal medical marijuana law allowed her to buy the drug with little hassle (California has since legalized recreational sales), and THC-infused vape pens let her use discreetly anytime she wanted.

“It just became so addicting,” she said. “I just couldn’t be without it. Every single thing I did I needed to do high.”

Guillermo, a 19-year-old Chicagoan, said the first time he got stoned “felt like I was a piece of butter melting on a stack of pancakes.” But the rapture faded quickly, and smoking weed soon became a joyless reflex akin to brushing his teeth in the morning, he said.

Potent marijuana frequently put him into hangoverlike “kush comas,” he said, and sapped his motivation and alertness so thoroughly that his mother threatened to put him into a mental hospital.

“I was just stoned all the time,” he said. “I was barely even there.”

Dr. Itai Danovitch, chair of the department of psychiatry at Cedars-Sinai in Los Angeles and a member of the American Society of Addiction Medicine, said the hallmarks of cannabis use disorder are similar to those of other addictions.

People become physically dependent on the drug, needing more to achieve the same effect, and they suffer withdrawal symptoms if they stop using. They lose control over their consumption. And they keep going even after their use causes them to suffer adverse consequences.

Those consequences, however, tend to be less pronounced with marijuana, leading some to overlook the drug’s problematic properties.

“People are able to function in a way that’s very hard to do with other drugs of abuse,” he said. “But they’re not functioning at the peak of their own performance.”

A 31-year-old Chicagoan who works in health care said she did well at her job despite smoking marijuana every day. That made it easy to rationalize her habit.

“Other people, when they have a bad day, can go home and have a couple glasses of wine,” she said. “(I thought that) me going home and smoking a bowl or three is the same thing. … I was this high achiever, but it was a double life.”

The marijuana, she believes, aggravated her depression and led to feelings of guilt and shame that ultimately prompted her to seek treatment. She entered a partial hospitalization program where she received eight hours of therapy a day to help her manage her cravings and understand the reasons behind her use.

“I don’t know the statistics, but it feels like there’s a higher rate of staying clean when you have that basis of treatment,” said the woman, who has been marijuana-free for nearly two years. “They’re not just keeping you from using. They’re teaching you fact-based coping mechanisms.”

Robb entered a similar program and said it helped him get through surprisingly intense withdrawal symptoms.

“I got headaches, dry heaves, extreme emotions and mood swings,” he said. “The first two weeks were bad. THC kills your ability to dream, so I was dreaming again for the first time in four years. My mind was catching up on everything I had repressed. Many of the reasons I started getting high in the first place were coming out in my dreams.”

But professional treatment is elusive for many drug users. Aaron Weiner, director of addiction services at Linden Oaks Behavioral Health, said people without insurance are often out of luck — a problem he expects to worsen now that Illinois has legalized marijuana.

“The end stage of addiction is you lose your job, and when you lose your job, you lose your insurance,” he said. “That is already an underserved community, and we’re just going to continue to see that exacerbated.”

Critics have warned that legal marijuana will increase addiction in Illinois, and a study published last year found that cannabis use disorder has indeed grown slightly in states that legalized pot.

The administration of Illinois Gov. J.B. Pritzker has reserved 20% of tax revenue from recreational marijuana for addiction treatment and prevention. That portion is projected to hit $25 million next year, according to the Illinois Department of Human Services, but won’t be reserved for any particular addiction.

Some of those in recovery for cannabis use disorder are indifferent to legalization, saying they had no trouble finding the drug when it was against the law. Cathy, a 64-year-old Chicago woman who has been off marijuana for several months, said legalization might even turn out to be a good thing.

“It used to be that it was hard to get help because you were always hiding it,” she said. “Now that it’s legal, my hope is that it will make it easier for people to admit they have a problem and go get help.”

Cathy sought that help in Marijuana Anonymous, a 12-step group founded in California in 1989. It came to the Chicago area roughly a decade ago, one member said, but has recently expanded. There are now three meetings in Chicago, two in Evanston and one that started last month in Westmont. Another might be coming to the neighborhood around Midway Airport.

Some experts question the efficacy of 12-step programs, which, given their anonymity and fluctuating membership, are notoriously hard to study. But Danovitch said they have proved helpful for many people, even if they can’t be considered formal treatment.

“We think of it as a community intervention,” he said. “It’s undoubtedly powerful and effective, but not everyone is willing to participate in it.”

Rick, 54, said Marijuana Anonymous helped him give up the drug when he started attending meetings about a decade ago. Since then, he said, the sense of fellowship has provided strong motivation to stay sober.

“These meetings have given me an accountability I could never maintain on my own,” he said. “They just keep me focused.”

A 29-year-old woman from Oak Brook who stopped smoking weed through Marijuana Anonymous, said quitting was tough. She went through a miserable withdrawal and was left in severe emotional fragility — a symptom, she believes, of having used marijuana to smother her emotions for nearly a decade.

Two years later, that has passed. Her depression and anxiety are gone, changes she chalks up to her abstinence. Even her once-cynical worldview has eased, she said, leaving her a more hopeful and engaged person.

“I rarely think about smoking anymore, which is a miracle given how obsessed I was two years ago,” she said. “When I do (think of it), I’m just reminded of how miserable I was and how I never want to go back to that.”