Introduction
Nausea and vomiting are among the most common complaints seen in community pharmacy practice. Nausea is a subjective feeling—an unpleasant urge to vomit, often accompanied by sweating, pallor, increased saliva and fast heartbeat. Vomiting (emesis) is the forceful expulsion of stomach contents through the mouth. It is usually preceded by retching, which is an unsuccessful attempt to vomit.
These symptoms may appear in gastrointestinal disorders, infections, pregnancy, cancer treatment and motion sickness. Because causes range from simple dietary issues to serious medical problems, proper assessment is essential.
Etiology (Causes)
Common causes of nausea and vomiting include:
- Food allergy or food poisoning
- Stomach or intestinal infections (“stomach flu”)
- Gastroesophageal reflux (GERD)
- Cancer chemotherapy or radiation therapy
- Migraine headaches
- Morning sickness during pregnancy
- Motion sickness or sea sickness
- Severe pain — e.g., kidney stones
- Excessive use of marijuana
More serious causes include:
- Appendicitis
- Intestinal obstruction
- Cancers or tumors
- Accidental ingestion of medicines or poisons
- Stomach or duodenal ulcers
Clinical Presentation
Along with nausea and vomiting, patients may show:
- Dehydration
- Weight loss
- Confusion
- Dry mucous membranes
- Reduced skin turgor
- Low blood pressure
- Muscle weakness or heart rhythm problems
- Metabolic alkalosis (in persistent vomiting)
Pathophysiology
The vomiting process occurs in three phases:
1. Nausea
The urge to vomit caused by delayed gastric emptying and increased autonomic activity.
2. Retching
Involuntary contraction of abdominal and chest muscles without expulsion of stomach contents.
3. Vomiting
Forceful expulsion of gastric contents due to strong muscle contractions and relaxation of esophageal sphincters.
Vomiting Centre and CTZ
The vomiting centre in the brainstem coordinates the reflex. It receives signals from sensory receptors in the stomach, intestines, pharynx and other organs via vagus and splanchnic nerves.
The Chemoreceptor Trigger Zone (CTZ) is stimulated by medicines, toxins, chemicals, metabolic changes and motion sickness.
Five major neurotransmitters involved in vomiting include:
- Dopamine
- Histamine
- 5-HT3 (serotonin)
- Acetylcholine (cholinergic)
- Substance P
Stimulation of these receptors in the vomiting centre and CTZ results in emesis.
Process of Vomiting (Simple Explanation)
- Deep breath → abdominal pressure increases
- Abdominal muscles contract
- Soft palate rises and epiglottis closes → prevents vomit entering the lungs
- Pyloric sphincter relaxes
- Esophagus relaxes → vomit expelled
Management of Nausea and Vomiting
Non-Pharmacological Measures
- Avoid heavy, oily or spicy foods
- Eat small, frequent meals
- Drink clear fluids (ORS, water, coconut water)
- Avoid strong smells and crowded areas
- Rest in a quiet, well-ventilated place
- Ginger tea or ginger lozenges may help
- Behavioral techniques and guided imagery (effectiveness varies)
Pharmacological Management
1. Antacids & Antisecretory Agents
Neutralize stomach acid; useful when nausea is linked to acidity or heartburn.
- Magnesium hydroxide
- Aluminum hydroxide
2. H2-Receptor Antagonists
- Cimetidine
- Ranitidine
- Famotidine
- Nizatidine
3. Proton Pump Inhibitors (PPIs)
- Omeprazole
- Esomeprazole
- Pantoprazole
- Lansoprazole
- Rabeprazole
4. Anticholinergics
Block muscarinic receptors in the vestibular system; effective for motion sickness.
- Scopolamine 0.5 mg every 72 hours
5. Antihistamines
Useful in nausea due to motion sickness, vertigo or migraine.
- Diphenhydramine
Side effects: drowsiness, dry mouth, blurred vision.
6. Dopamine Antagonists
Block D2 receptors in the CTZ.
- Chlorpromazine 10–25 mg every 4–6 hours
- Promethazine 12.5–25 mg every 4–6 hours
- Domperidone 10 mg every 8 hours
7. Serotonin (5-HT3) Antagonists
Very effective for chemotherapy-induced nausea and post-operative vomiting.
- Ondansetron: 32 mg IV before chemotherapy OR 8 mg orally before chemotherapy and repeated every 12 hours for 1–2 days.
When to Refer to a Doctor (Red Flags)
Immediate referral is required if:
- Poisoning is suspected
- Vomiting lasts more than 24 hours
- Blood present in vomit
- Severe abdominal pain or headache with stiff neck
- Signs of dehydration — dry mouth, low urine output, dark urine
Detailed Notes:
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