We are looking for opioid users who:

• use opioids everyday or nearly everyday
• have used opioids intravenously (injected)
• get sick when no taking opioids
• are ages 18-55
• are able to live at the UK hospital for 5 weeks

The purpose of this study is to learn more about how opioids produce their rewarding effects

Qualified participants will be paid for participation

Travel expenses may be reimbursed