Participants (n=25) will receive three doses of a placebo drink for seven days.

Cold Pressor Test is a well-validated measure of pain sensitivity that consistently elicits hyperalgesia in people with OUD, including those taking medications for OUD. Individuals will perform the test no later than the end of the first day of KS and again on the last day of KS. Participants plunge their dominant hand and forearm in an ice bath maintained at 5 degrees C. There are two outcomes associated with this test: pain threshold and pain tolerance. Pain threshold is the duration of time lapsed before the individual rates the sensation as painful. Pain tolerance is the duration of time the individuals keeps their arm immersed before it becomes subjectively unbearable (i.e., the individual removes their arm from the bath). Trials will be terminated if their arm is still submerged after five minutes, since pain responses on this task tend to peak by 90 seconds and diminish to below tolerance threshold within five minutes of immersion.

Desires for Drugs Questionnaire (DDQ): A 14-item assessment measured on a 7-point Likert scale with 0 representing "totally disagree" and 6 representing "totally agree" and is composed of three subscales: Desire and Intention, Negative Reinforcement, and Control. A higher score indicates a higher desire for the drug.

A six-item validated visual analogue scale of self-report of mood. The six items represent the three primary factors of the Profile of Mood States (happy, sad, alert, tired, relaxed, nervous) Participants will see a horizontal line with 0 on the left end and 100 on the right end and will be asked "With zero (0) meaning 'Not [Happy, Sad, etc.] At All' and 100 meaning '[Happiest/Saddest, etc.] Ever' please indicate the point on the line that represents your current state."

Graded Chronic Pain Scale (GCPS-R) is a 6-item instrument that evaluates chronic pains severity (intensity and impact on life activities). Graded scores range from 0-3 (0=Chronic Pain Absent, 1=Mild Chronic Pain, 2=Bothersome Chronic Pain, 3=High Impact Chronic Pain). Higher scores indicate higher impact of chronic pain.

Positive and Negative Affect Schedule (PANAS) is a 20 item Likert type instrument in which participants rate the extent to which they have felt specific emotions (both positive and negative) over the past week (or since they last completed the survey). The PANAS uses a 1-5 scale (1=very slightly or not at all, 2=a little, 3=moderately, 4=quite a bit, 5=extremely) for each item, with higher scores indicating a higher extent that a participant has experienced a particular emotion. Scores range from 20-100.