Nausea and vomiting may result from a variety of causes including gastrointestinal obstruction, or infiltration of the wall of the GI tract, liver metastases, brain or meningeal metastases, azotemia, hypercalcemia, electrolyte problems, or from treatment including radiation, chemotherapy, hormone or biological therapy.

The cause should be diligently sought and, if possible, treated specifically.

A number of antiemetic medications can be helpful, particularly for treatment related nausea. The large number of medications available attests to the fact that none are uniformly effective.

Drugs which block the chemoreceptor center in the brain include phenothiazines: prochlorperazine (Stemetil), butyrophenones: haloperidol (Haldol, etc.) or droperidol (Inapsine) and the substituted benzamide: metoclopramide (Maxeran, Reglan, etc.). Metoclopramide has an additional effect on the gastrointestinal tract of increasing motility and gastric emptying. Tetrahydrocannabinol or the synthetic cannabinoid, nabilone (Cesamet), may be helpful in some patients. Corticosteroids can be a useful adjuvant or by themselves suppress nausea and vomiting. Dexamethasone or methyl prednisolone have been most often used.

Some new agents including serotonin (5HT3) receptor antagonists, such as ondansetron (Zofran), are just coming on to the market after clinical testing which has been encouraging. The anticipated cost of these agents makes it likely that they can not be used routinely, but only in special situations.

Frequently the use of a combination of antiemetic agents may be useful, e.g. prochlorperazine 10 mg, po, iv, or suppository, q4-6h, dexamethasone 4-8 mg, po or iv q4-8h, plus or minus nabilone 1 mg, po, q8-12h. The addition of diphenhydramine 25 mg, po or iv, may prevent the dystonic reactions and restlessness produced by the prochlorperazine, and lorazepam may be helpful in anxious, tense patients.