The home-made drug that Oleg and Sasha inject is known as krokodil, or "crocodile". It is desomorphine, a synthetic opiate many times more powerful than heroin that is created from a complex chain of mixing and chemical reactions, which the addicts perform from memory several times a day. While heroin costs from £20 to £60 per dose, desomorphine can be "cooked" from codeine-based headache pills that cost £2 per pack, and other household ingredients available cheaply from the markets.
It is a drug for the poor, and its effects are horrific. It was given its reptilian name because its poisonous ingredients quickly turn the skin scaly. Worse follows. Oleg and Sasha have not been using for long, but Oleg has rotting sores on the back of his neck.
"If you miss the vein, that's an abscess straight away," says Sasha. Essentially, they are injecting poison directly into their flesh. One of their friends, in a neighbouring apartment block, is further down the line.
"She won't go to hospital, she just keeps injecting. Her flesh is falling off and she can hardly move anymore," says Sasha. Photographs of late-stage krokodil addicts are disturbing in the extreme. Flesh goes grey and peels away to leave bones exposed. People literally rot to death.
Russian heroin addicts first discovered how to make krokodil around four years ago, and there has been a steady rise in consumption, with a sudden peak in recent months. "Over the past five years, sales of codeine-based tablets have grown by dozens of times," says Viktor Ivanov, the head of Russia's Drug Control Agency. "It's pretty obvious that it's not because everyone has suddenly developed headaches."