Sally Marlow investigates the hidden problem of addiction to over-the-counter painkillers.

Addictions researcher, Dr Sally Marlow, investigates fears that easy access to powerful painkillers could be creating a large, but hidden problem of addiction.

Painkillers are widely available over-the-counter, and combinations containing codeine, which is addictive, can be purchased from pharmacists and on the internet.

Teenager, Alice, tells Sally about secretly buying huge numbers of painkillers on her way to school while she was wearing her school uniform. She used her lunch money to buy multiple packs from several stores, switching shops when she was questioned by pharmacists.

And Steve describes how his serious codeine addiction began after treating tooth pain with the drug. The side effects helped his anxiety and for years he was doctoring tablets in order to increase his codeine intake.

Some health professionals believe easy access is fuelling a potential health crisis and say those with serious dependency problems, are hidden below the healthcare radar.

Only a tiny percentage of people with an addiction to painkillers find their way to traditional substance misuse services, fuelling concerns that there is a large, but hidden group, who aren't getting help with their dependency.

David Grieve, who set up the charity, Over-count, 21 years ago after his own serious addiction to over-the-counter cough mixture, believes the number of people dependent on painkillers is growing, fuelled by easy availability on the internet.

Between 30-35% of visitors to his website say when they are refused purchases by pharmacists, they buy online instead.

Fabrizio Shiffano, Professor of Clinical Pharmacology at the University of Hertfordshire and a member of the government's Advisory Council on the Misuse of Drugs, demonstrates how easy it is to buy potent painkillers online and Dr Paolo DeLuca, a senior research fellow in addictive behaviour at King's College, London, tells Sally about a three year international study, the Codemisused Project, which aims to discover the scale of codeine use and misuse. Dr DeLuca is leading the British arm of the study and he hopes that research will fill the current gap in knowledge so that if action is needed to reduce the risk to individuals, it can be based on evidence.

Producer: Fiona Hill.