Ketamine, introduced in 1966 as an anesthetic, is increasingly showing up in private clinics nationwide as a treatment for chronic pain. While the drug is indeed a potent pain reliever, its effect is short-lived; and use may be accompanied by headache, nausea, and fatigue, among other adverse outcomes. There also is a risk of abuse given ketamine's euphoric properties, which have earned it a reputation as a club drug. For these and other reasons, clinicians are apprehensive about pain centers administering off-label ketamine infusions for conditions ranging from fibromyalgia to migraines. The jury is still out, they say, on whether ketamine is a viable option for pain management. While some studies have reported a benefit, the quality of the evidence is low due to the small scale, limited generalization, and lack of effective blinding in these investigations. Moreover, research evaluating ketamine for chronic pain has focused on I.V. infusion, which inflates the cost of treatment and limits its use over the long term. The American Society of Regional Anesthesia and Pain Medicine is expected to issue guidelines on ketamine use for pain management within 6 months, but University of Pittsburgh anesthesia and psychiatry professor Ajay Wasan, MD, says clinicians will not get much real direction until more is known. "It's not clear at all at this point exactly how to administer it," he points out. "We don't really know how beneficial it is or which patients would be the best ones to put on it. We also don't know exactly how much ketamine to infuse and for how long and how frequently to give the infusions."