Nausea and Vomiting

Key facts

• Nausea is the unsettled feeling that often precedes vomiting, the forceful expulsion of stomach contents; together they are among the most common symptoms people experience.
• Causes include food poisoning, motion sickness, chemotherapy, pregnancy, and acute gastroenteritis.
• Mild cases usually settle with rest and small sips of clear fluid; persistent or severe cases are treated with medicines such as ondansetron and chlorpromazine.
• Seek prompt care if vomiting comes with severe abdominal pain, blood, dehydration, or follows a head injury.

What triggers them

The vomiting reflex is controlled by the brainstem and can be triggered by gut irritation, inner-ear disturbance, toxins in the bloodstream, certain medicines, or signals from the brain itself during anxiety or migraine. Unfamiliar food and water are frequent culprits for travelers, and viral gastroenteritis spreads easily wherever people share close quarters, such as schools, offices, or cruise ships. Alcohol and some prescription medicines, including certain antibiotics and painkillers, can irritate the stomach lining enough to trigger both symptoms.

How they are treated

Mild cases often settle with rest, small sips of clear fluid, and bland food. When symptoms are severe, persistent, or tied to a specific cause such as chemotherapy or surgery, medicines that block nausea signals in the brain and gut are used. Ondansetron works by blocking serotonin receptors and is widely used for chemotherapy-related and post-operative nausea. Chlorpromazine acts on dopamine pathways and is used for severe or intractable vomiting, including cases linked to mental health conditions. Both sit within the digestive health range.

When to see a doctor

Seek prompt medical attention if vomiting is accompanied by severe abdominal pain, blood in vomit, signs of dehydration, or if it follows a head injury.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.