The main finding of this research is that a number of changes in relation to drug use occur as a result of migration itself. These are both harm-increasing and harm-reducing, but a majority of respondents self-reported harm-increasing changes in drug use, particularly in relation to HIV infection. Irish drug users had close networks of friends and relatives whom they could access when they came to Britain. However, they were reluctant to approach services. When they did so, Irish drug users traveled long distances in London to access services that were known to work with their community. In Ireland, drug users tended to use different drugs and at different strengths than drug users in Britain. These differences meant that Irish drug users were at a high risk of overdosing and experiencing physical harm when using drugs in England. Together, the many problems associated with migration and drug-use problems render Irish drug users a highly vulnerable group within the British drug-using population. Figures, note, references