In the back room of a messy flat somewhere in the dizzying sprawl of Dhaka, a young man tears off a strip of aluminium foil and places on it a tangerine-coloured pill.

He rolls several frayed 10 Bangladeshi Taka banknotes together into a makeshift pipe and then strikes a cigarette lighter below the foil. Soon, he is inhaling the acrid fumes from the burning tablet, taking long drags which he sucks deep into his lungs.

After three hits, the whole pill has been smoked. The long-time user – who clenches an old plastic bottle top between his teeth to prevent additional damage to his mouth – is instantly wide-eyed.

The slumberous demeanour he projected half an hour before is gone, replaced by a manic, unhinged energy. Though it is only mid-morning, he is now unlikely to feel tired again before the same time tomorrow.

This is the routine fuelled by yaba, a tiny pill manufactured mostly in Myanmar. Ya ba means “crazy medicine” in Thailand, where it was once used legally by long haul truck drivers. Decades after being outlawed there, it is wreaking havoc with lives in Bangladesh.

Yaba tablets contain a heady mixture of methamphetamine and caffeine which provides users with a powerful energy surge but has serious physical and mental health consequences when abused over a long period.

Demand has spread widely across Asia over the last two decades, particularly in Bangladesh which shares a porous 160-mile border with Myanmar.

Seizures around the coastal city of Cox’s Bazar are frequent, with traffickers using the vast Rohingya refugee camps nearby as a drop zone for consignments and an easy recruiting ground for mules to carry yaba onward to Dhaka. More than a million pills were confiscated in separate operations in the region in April alone.

A massive crackdown against the yaba trade in 2018 resulted in 211 deaths in Bangladesh but the trade continues.

The Telegraph was granted exclusive access to the Central Drug Addiction Treatment Centre in Dhaka, where the majority of addicts receiving detox therapy are recovering yaba users.

Located on the upper floor of a drab building with peeling paintwork, the secure unit is protected by uniformed guards. They stand in front of padlocked retractable steel grilles which are temporarily pulled back for us to enter.

Behind, the expectant faces of the current residents greet us. Some seem delighted by the distraction while others bear hardened, resentful expressions.

They have mostly been sent here, for up to a month, by their parents or other family members. Though the insistent cacophony of Dhaka traffic is just outside, they are effectively imprisoned, excluded from the streets on which they can so easily get hold of the £1-a-pop yaba pills which keep them going.

Though staff are careful to insist the men are not inmates, the metal bars over the windows suggest otherwise. A tally counting down the days has been scratched into the wall at the back. They are restrained here until they can prove they are clean.

Shafi, 23, is six days into his stint. He is a bright young man with an engaging manner, a high achieving college student until he started using yaba. The son of a retired officer in the Bangladeshi army and a highly respected academic, he was a young man with the connections to go far.

He was introduced to yaba by his uncle, who imported bricks of 10,000 pills into Bangladesh from Myanmar.

“I used to grab a fistful of yaba pills from his stash,” Shafi recalls. “I was only 13. I was just taking it out of curiosity. I could just take them whenever I wanted to. It cost me nothing.”

“At my worst, I went for seven whole days with no sleep,” he confesses. “At that point, I was so mentally unstable. I went from being someone who was known for being polite and cool to always losing my temper with the people around me. When my mother called me to eat I would just scream and shout at her. One time, I didn’t eat for four days.”

For some of the most serious cases at the rehab centre, including Shafi, the sleepless delirium of yaba provided a reason for then moving onto stronger opioid drugs, a means of coming down after staying awake for several days.

“To compensate, I would take heroin,” Shafi explains. “I was stuck in this cycle all the time – one day yaba, one day heroin. I would also take fentanyl and morphine, whatever I could get hold of. I funded my habits by providing online casino access for other users.

“I contracted appendicitis because of my drug use. I went to hospital for surgery but in the end the surgeon said he wouldn’t operate on me because my tolerance for the pethidine they wanted to give me as a sedative and pain relief was so high. They couldn’t take the risk of going ahead.”

Talking with Shafi, who flits seamlessly between English with me and Bengali with the other young men surrounding us, it is hard to believe he reached such a nadir.

His arms and hands, in which he holds his bowl ready for a meal of rice and lentils, are covered by needle puncture scars.

But, he explains, the cheap, easy availability of yaba has seeped into every corner of society in Dhaka, from the roughest slums to the more upmarket neighbourhood where his family lives. “It is an epidemic which has infected the whole country,” he concedes.

This is not Shafi’s first time at a rehab clinic. His family paid for him to be in a private rehab centre for five months in 2023. The morning after checking out he was taking yaba again.

“I caused my family extreme pain,” Shafi is willing to concede. “I had a good place in a college to complete my diploma but then I dropped out because I was taking so much yaba. This time around it’s my decision to come here to clean up. I have so many health complications. My veins are shrinking and drying out – I have to do something.”

Shafi drifts back to his dormitory. He lies on his thin mattress on a metal frame bed and stares at the ceiling. There are 32 beds in the clinic’s four dormitories, fully occupied most of the time.

During the afternoon, the yaba dependents sit on rows of benches while they are addressed by members of the medical team. There are stark warnings of the dangers of drugs on the wall, including a poster which reads ‘Drug abuse? No excuse’ above a picture of a noose. Another displays the adverse effects of yaba on the human body.

Sifat, 27, explains how he cannot get through the day without taking yaba, after similarly dabbling as a teenager.

His dependence became more deeply entrenched when he acquired a job as a backstreet salesman in a slum. Yaba gave him the extra boost he needed to talk non-stop to potential customers every day.

Placated by several weeks inside the facility, Sifat nevertheless comes across as a coiled spring of pent-up energy. His experience with yaba transformed him from being an easy-going lad into a violent street thug.

“The immediate effect of yaba on me was that I would lose my temper,” says Sifat. “I would start attacking others for silly reasons, sometimes with my fists and sometimes with a stick.

“Sometimes I would attack my own friends on the streets, and then at home I vandalised the furniture. I would hurl random objects across the room because I was always angry.”

Getting married in 2023 temporarily curtailed Sifat’s habit, but he went back to yaba when the relationship ran into problems. He would take five pills a day, causing incredible disruption to his sleep pattern and appetite. At his worst, Sifat recalls, he would be up for three days and then sleep uninterrupted for 24 hours.

“Yaba makes me feel like I can achieve anything,” Sifat admits, “but it has caused me and my family so much harm. I feel massive regret and just want to be a good person again.”

Many of the dormitory occupants are alarmingly young, fresh-faced teenagers barely out of school.

Some, like 17-year-old Amin, started using yaba when they were still going through puberty. His decline follows a familiar routine, in which the demands of the manual labour he had been forced into as a child from a poor family of eight children were softened by the stimulant effects of the drug.

“It gave me a superhuman feeling,” he recalls, “like I was the best, above everyone around me. Very quickly, I was spending the money I was supposed to give back to my family on yaba. After that, I needed to take even more to stay alert for longer, so I began stealing things from home and selling them.

“When my parents found out they brought me here because I was not able to stop by myself, even though I promised I would.”

“Yaba has destroyed our social architecture,” says the Centre’s resident psychiatrist, Dr Mohammed Rahanul Islam. “We are in a position akin to China in the 1840s, before the opium wars. In rural areas, illegal money and power is linked in with yaba.

“Here we deal with people who take yaba, which can be methamphetamine mixed with synthetic caffeine, as well as other synthetic opioids, and then take another substance to help them sleep. This mixture has been described as a poor man’s speedball, like cocaine and heroin in other countries, but with inferior options.”

There have been multiple cases of young people dependent on yaba suffering strokes and heart failure even though the drug is not chemically addictive in the same way as heroin.

Dr Islam says yaba has infiltrated rural parts of Bangladesh, as well as its teeming cities. Its use is widespread among rickshaw drivers, who need to work long hours to make enough money, he explains.

As recounted by Shafi and several of the other users I meet, he confirms the connection between the sustained nervous energy which yaba provides and compulsive online gambling, which has also become a problem in Bangladesh.

Several of the young men tell me they were enticed into taking yaba by a widespread belief that it boosts sexual potency – a strong sales pitch in a conservative Muslim nation like Bangladesh.

“It’s very frustrating for us to treat them,” Dr Islam continues. “There is no specific medication we can use for treatment because the design of the drug is so elusive.”

Regardless of the authorities’ determination, the ability of the drug lords to churn out millions of yaba pills from camps in the jungle borders of Myanmar is relentless. It is mostly manufactured in the militia-controlled Shan state, far from prying eyes. For every operation that is closed down, another swiftly springs up.

“The reason yaba has become so prevalent here is that it is so easy to transport and far cheaper to buy than other drugs,” says Adnan Zobayer, a psychiatric social worker for the Bangladesh Government’s Department of Narcotics Control.

“People get an easy buzz and quickly become dependent. When you start one yaba pill can keep you going for a week but that soon increases to three or four. It’s when people are addicted that they develop anxiety, schizophrenia, depression and personality disorders. The number of users keeps increasing, and the majority of them are teenagers.”

In a separate office, rehab counsellor Sumi Khan is conducting an exit interview with another young man before he can be released back into the intoxicating mayhem of Dhaka.

His mumbled answers are uniformly affirmative. The counsellor can tick all of the boxes on her form.

But back out there, trapped by the daily drudgery which makes life so hard for so many of Bangladesh’s 178 million people, there is little to dull the allure of yaba.

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