Intravenous metoclopramide, intravenous prochlorperazine, or intranasal lidocaine are other potential options. Metoclopramide or prochlorperazine are the recommended treatment for those who present to the emergency department. Haloperidol may also be useful in this group. A single dose of intravenous dexamethasone, when added to standard treatment of a migraine attack, is associated with a 26% decrease in headache recurrence in the following 72 hours. Spinal manipulation for treating an ongoing migraine headache is not supported by evidence. It is recommended that opioids and barbiturates not be used due to questionable efficacy, addictive potential, and the risk of rebound headache. There is tentative evidence that propofol may be useful if other measures are not effective.