Understanding Nausea in a Hospital Setting
Nausea and vomiting are distressing symptoms that can arise in a hospital for numerous reasons [1.2.6]. They are particularly common after surgery, a condition known as postoperative nausea and vomiting (PONV), which affects around 30% of surgical patients [1.6.1]. Other major causes include side effects from medications like chemotherapy (CINV) or opioids, infections, and issues related to the digestive system like gastroenteritis [1.2.6, 1.6.3]. The body's mechanism for nausea is complex, involving multiple neurohumoral pathways and chemoreceptors in the brain and gut [1.2.1]. Because of this complexity, healthcare professionals have a variety of medications, called antiemetics, that target different pathways to control these symptoms effectively [1.2.1]. The choice of drug depends on the underlying cause, the patient's medical history, and the specific clinical situation [1.2.2].
Common Classes of Antiemetic Medications
Hospitals use several classes of drugs to manage nausea, each with a different mechanism of action [1.2.1]. The selection is tailored to the specific cause of the nausea, whether it's from motion sickness, surgery, or chemotherapy [1.2.2].
Serotonin (5-HT3) Receptor Antagonists
This is one of the most common classes of anti-nausea medication used in hospitals [1.6.2].
- Examples: Ondansetron (Zofran), granisetron (Kytril), and palonosetron (Aloxi) [1.2.1, 1.2.3].
- How They Work: These drugs block serotonin, a chemical that sends nausea signals to the brain from the gut [1.4.3]. They are highly effective for nausea caused by chemotherapy, radiation, and surgery [1.2.5, 1.2.6]. Ondansetron is a first-line agent for many patients due to its efficacy and favorable side-effect profile compared to other drugs [1.3.4].
- Administration: They are available in various forms, including intravenous (IV), oral tablets, and orally disintegrating tablets (ODT) [1.2.1, 1.2.5].
- Common Side Effects: Headache, fatigue, dizziness, and constipation are common [1.2.1, 1.5.3]. A more serious, though less common, side effect is the potential for QT prolongation, an issue with the heart's rhythm [1.5.3].
Dopamine Antagonists
This class includes several types of drugs that work by blocking dopamine receptors in the brain's chemoreceptor trigger zone [1.2.1].
- Phenothiazines: Examples include prochlorperazine (Compazine) and promethazine (Phenergan) [1.2.1]. Promethazine is also an antihistamine and is effective but can cause significant sedation [1.4.3, 1.4.5].
- Butyrophenones: Droperidol and haloperidol are potent antiemetics in this category. However, concerns about side effects, including QT prolongation, have limited their use [1.2.1].
- Benzamides: Metoclopramide (Reglan) is a primary example. It not only blocks dopamine receptors but also helps move food through the digestive tract [1.2.1, 1.2.4].
- Administration: These are available as IV, intramuscular (IM), oral, and rectal suppositories [1.2.1].
- Common Side Effects: Drowsiness, dizziness, and restlessness are common [1.5.2]. A significant concern with dopamine antagonists is the risk of extrapyramidal symptoms, such as muscle spasms and tardive dyskinesia (involuntary movements) [1.2.1].
Other Important Antiemetic Classes
- Antihistamines: Drugs like diphenhydramine (Benadryl) and meclizine (Antivert) are particularly effective for nausea caused by motion sickness or vestibular issues (inner ear problems) because they block histamine H1 receptors [1.2.1, 1.2.3]. Sedation is a very common side effect [1.2.1].
- Corticosteroids: Dexamethasone is often used, either alone or in combination with other antiemetics, to prevent PONV and CINV [1.6.5]. Its exact mechanism is not fully understood but it is highly effective [1.2.1].
- NK-1 Receptor Antagonists: Aprepitant (Emend) and fosaprepitant are newer agents that block the neurokinin-1 (NK-1) receptor. They are highly effective for both immediate and delayed nausea from chemotherapy [1.2.1, 1.7.6].
- Benzodiazepines: Lorazepam (Ativan) can be used to treat anticipatory nausea and vomiting, often seen in patients anxious about chemotherapy [1.2.3, 1.7.3]. They work by reducing anxiety rather than through a direct antiemetic effect [1.2.5].
Medication Comparison Table
When treating nausea in a hospital, clinicians often choose between several frontline drugs. Here’s a comparison of three common options: ondansetron, promethazine, and metoclopramide.
| Feature | Ondansetron (Zofran) | Promethazine (Phenergan) | Metoclopramide (Reglan) |
|---|---|---|---|
| Drug Class | Serotonin (5-HT3) antagonist [1.4.7] | Phenothiazine antiemetic, Antihistamine [1.4.7] | GI stimulant, Miscellaneous antiemetic [1.2.3] |
| Primary Use | Chemotherapy-induced and postoperative nausea [1.4.1] | Motion sickness, allergies, nausea/vomiting [1.4.1] | Nausea from GI issues, chemotherapy [1.2.4] |
| Common Side Effects | Headache, fatigue, constipation [1.5.3] | Drowsiness, dizziness, confusion, dry mouth [1.4.1, 1.5.1] | Drowsiness, restlessness, extrapyramidal symptoms [1.2.1] |
| Key Risks | QT prolongation (heart rhythm issue) [1.5.1] | Severe sedation, respiratory depression in children <2 [1.4.1] | Tardive dyskinesia (involuntary movements) with long-term use [1.2.1] |
| Administration | IV, oral tablet, dissolving tablet [1.4.7] | IV, oral tablet, syrup, rectal suppository [1.4.7] | IV, oral tablet [1.2.1, 1.2.3] |
Conclusion
The management of nausea in a hospital setting is a critical component of patient care that improves comfort and prevents complications like dehydration [1.8.2]. Doctors have access to a wide array of antiemetic medications that target different neurological and physiological pathways. The choice of what they give you in the hospital for nausea—whether it's a serotonin antagonist like ondansetron, a dopamine antagonist like promethazine, or another agent like dexamethasone—is carefully considered based on the cause of the nausea, patient-specific risk factors, and the medication's side effect profile [1.6.2]. Combining drugs from different classes is also a common strategy for high-risk patients to achieve better control [1.6.5].
Authoritative Link: Learn more about antiemetic medications from the National Library of Medicine.
