There are many variations on the "magic mouthwash, "swish & spit" formula. Mine was Benadryl, morphine and lidocaine. All of the concoctions have to be compounded by a pharmacist. Typically it shouldn't be swallowed as it can numb the gag reflex and make it possible to aspirate it into the lungs (very bad - can cause pneumonia). The magic mouthwash is typically used prior to attempting to eat or drink orally.

Most of us had Duragesic patches (as ChristineB mentioned) for long term pain relief (ie anytime pain meds are required for more than a month or so) with morphine for short term (or breakthrough pain). You didn't mention anything about that (and that is the singlemost important and efficacious pain control method). Morphine is fast acting - in liquid form, about 4 minutes (IV instantaneous). Other oral painkillers can take an hour or more to reach full effect.

Oxycontin is sometimes used alternatively for high pain levels and there is also a time release morphine patch available now.

Vicodin and similar synthetic narcotics are "medium strength" compared to Duragesic (AKA Fentanyl).

All pain meds can cause constipation issues so that must be carefully managed.

Her level of pain should be communicated to her doctors using a scale of 1-10 with 8-10 being the worst and unacceptable. The goal of proper pain management is to keep the pain threshold below 3.

See: http://www.oralcancerfoundation.org/treatment/pdf/pain.pdf