Straight Life: India's recovering drug addicts

Drug and alcohol abuse is fast becoming an area of concern in India, which according to UN data has 2 million people who use opiates.

The Indian state of West Bengal has been identified in the National Health Survey as one of the pockets with the highest use in India. Although there are treatment centres dotted around the country, there is a gap between the number of centres and the prevalence of drug abuse. Many who seek treatment end up lapsing back into addiction.

Photographer Ronny Sen documents the struggles of some recovering addicts in the city of Kolkata (Calcutta) in West Bengal.

Clean seven years: It took 30 treatments for Anindya C to finally quit drugs. A film actor, he is now an ambassador for a Kolkata police programme against drug abuse and illicit trafficking

Clean one month: Arijit N is one of Kolkata's oldest addicts, and has been using drugs for the last 33 years. He says that when he was first exposed to brown sugar (an adulterated form of heroin) people would openly smoke it at cafés in the city. He stays with his mother now. "Whenever she is away she puts me in a treatment centre. She never leaves me alone in the house".

Clean two years: Otillia started using drugs at 16 in school. She says, "After my father died I became extremely lonely and depressed. Drugs helped me back then. I did anything and everything to continue using drugs." She wants to finish her education now.

Clean 23 years: One of Kolkata's oldest recovering addicts, Deep M says, "There was a time I had given up all hope. My mother once tried to commit suicide due to my usage and she was admitted to the same hospital I had been entered into for treatment. I never thought I would live this long."

Clean one month: Alia Zafar started using drugs at the age of 16 and has been to rehabilitation three times. She has been trying to quit since 2005. "I couldn't stop using drugs because of my big fat denial". Ms Zafar is determined to stay clean this time. She feels that in India, it's harder for women to kick the habit because there are very few women's treatment centres and people are reluctant to accept them in the mainstream even after they have quit.

Clean nine years: Tirthankar S, a former student of the academy of fine arts in Kolkata, is standing near the toilet of a local market, a place he would often go to hide and use drugs.

Clean 16 years: Kanishka M remembers his early days in recovery when his father refused to fund his treatment. It was his wife who mortgaged her gold jewellery and arranged money for his treatment. There was no looking back after that.

All images and stories have been used with the permission of the subjects.