What is the appropriate workup for nausea?

From the Guidelines

The workup for nausea should begin with a thorough history and physical examination to identify potential causes, and prophylactic treatment with antiemetic agents is highly recommended for patients with a prior history of opioid-induced nausea, as stated in the 2019 NCCN clinical practice guidelines 1. When evaluating nausea, key elements to consider include onset, duration, aggravating and alleviating factors, associated symptoms, medication use, and recent dietary changes.

• Laboratory tests should include complete blood count, comprehensive metabolic panel, amylase, lipase, pregnancy test in women of childbearing age, and thyroid function tests.
• Additional tests may include urinalysis, stool studies if infectious causes are suspected, and an abdominal ultrasound or CT scan if structural abnormalities are considered. For persistent nausea, an upper endoscopy may be warranted to evaluate for gastritis, ulcers, or other upper GI pathology.
• If neurological symptoms are present, brain imaging should be considered.
• For suspected gastroparesis, a gastric emptying study is appropriate. Treatment should target the underlying cause while providing symptomatic relief with antiemetics such as ondansetron 4-8mg every 8 hours, promethazine 12.5-25mg every 6 hours, or metoclopramide 10mg before meals and at bedtime, as recommended by the 2008 ESMO clinical recommendations for prophylaxis 1. Hydration status should be monitored and IV fluids administered if dehydration is present.
• This systematic approach helps identify the underlying cause of nausea, which is essential since nausea is a symptom rather than a diagnosis, and can result from gastrointestinal, neurological, metabolic, medication-related, or psychological conditions.
• According to the 2008 Journal of Clinical Oncology study, nausea and vomiting are common symptoms in cancer patients, and effective prevention and management are crucial to improve patients' quality of life 1.

From the FDA Drug Label

To Control Severe Nausea and Vomiting: Adjust dosage to the response of the individual. Begin with the lowest recommended dosage. Oral Dosage-Tablets: Usually one 5mg or 10mg tablet 3 or 4 times daily. Ondansetron tablets are indicated for the prevention of nausea and vomiting associated with: highly emetogenic cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m 2.

The treatment for nausea includes ondansetron and prochlorperazine.

• Ondansetron is used for the prevention of nausea and vomiting associated with cancer chemotherapy and radiotherapy.
• Prochlorperazine is used to control severe nausea and vomiting. The dosage of these medications varies depending on the individual and the severity of the condition.
• Ondansetron dosage is described in Table 1 for adults and Table 2 for pediatrics.
• Prochlorperazine dosage is usually one 5mg or 10mg tablet 3 or 4 times daily. 2 3

From the Research

Nausea Workup

• Nausea and vomiting are common symptoms with many possible causes, including the adverse effects of drugs 4
• The main antiemetic classes include antagonists of the serotonin, dopamine, histamine, muscarinic and neurokinin systems, corticosteroids and benzodiazepines 4
• A careful history of related factors is essential to guide the initial evaluation and narrow the differential diagnosis, including associated symptoms, timing of onset and duration of symptoms, exacerbating or relieving factors, alarm symptoms, medication and substance use, relationship with recent food ingestion, and comorbidities 5

Evaluation of Nausea and Vomiting

• Acute nausea and vomiting last up to 7 days and are typically treated symptomatically and without an extensive evaluation in the absence of alarm symptoms 5
• Chronic nausea and vomiting last 4 weeks or longer and have a broad differential diagnosis, including gastrointestinal, infectious, metabolic, neurologic, psychiatric, or related to medications and toxins 5
• A 5-step approach to the clinical evaluation and treatment of nausea and vomiting includes defining what the patient means by nausea and vomiting, determining whether symptoms are acute or chronic, considering medication or toxin adverse effects, using the patient's presentation to formulate a differential diagnosis, and directing treatment based on knowledge of neurotransmitters and receptors involved in the emetic pathways 6

Treatment of Nausea and Vomiting

• Antiemetic drugs effectively reduce symptoms of acute nausea and vomiting, but chronic symptoms are often more challenging to treat 5
• When a specific etiology is not identified, a serotonin antagonist or dopamine antagonist can be used, but medications may also target the suspected cause of symptoms and the neurotransmitters involved in central and peripheral pathways of nausea and vomiting 5
• Ondansetron is as effective as promethazine and is not associated with sedation or akathisia, making it a suitable option for relief of nausea or vomiting for most patient populations in the emergency department 7
• Ondansetron has been shown to be more effective than metoclopramide in the prevention of chemotherapy-induced nausea and vomiting, with a relative risk of zero emesis of 1.72 (95% CI 1.45 to 1.97) 8