An Overview of Nausea and Vomiting in Adults


Published: 08 April 2021

Nausea and vomiting are common symptoms that are associated with a variety of conditions (Mayo Clinic 2020).

What are Nausea and Vomiting?

It is important to note that nausea and vomiting are not conditions themselves - rather, they are non-specific symptoms (Cleveland Clinic 2019).

  • Nausea describes a feeling of unease in the stomach, chest or throat. Someone experiencing nausea will usually feel the urge to vomit, but vomiting will not necessarily occur.
  • Vomiting (emesis) is the physical act of forcibly ejecting stomach contents through the mouth. This may be a voluntary or involuntary action. Vomiting may occur independently of nausea.

(Cleveland Clinic 2019; Encyclopedia Britannica 2017; Shiel 2020)

Vomiting is a protective mechanism used to expel harmful substances in the stomach. It may also occur in response to irritation in the gut (NHS Inform 2020).

While nausea and vomiting may indicate a serious condition, they are not usually a cause for concern and generally resolve after one to two days (NHS Inform 2020).

Symptoms that are often associated with nausea and vomiting include:

  • Abdominal pain
  • Diarrhoea
  • Headache
  • Fever
  • Gas
  • Dizziness
  • Lightheadedness.

(Shiel 2020)

Acute nausea and vomiting generally describes symptoms that resolve within 48 hours. Nausea and vomiting that persists for over 48 hours may lead to complications or indicate a more serious illness (Knott 2020).

nausea vomiting man with abdominal pain
Abdominal pain and other symptoms may be associated with nausea and vomiting.

The Physiology of Vomiting

There are several sites involved in nausea and vomiting, in particular:

  • The chemoreceptor trigger zone (CTZ) , which is located in the brain near the vomiting centre in the medulla
  • The gastrointestinal tract
  • The vestibular system, which is responsible for balance, spatial orientation and movement
  • The higher centres in the cortex and thalamus.

(Athavale, Athavale & Roberts 2020; MacDougall & Sharma 2020)

These sites relay information to the vomiting centre, which is located in the medulla oblongata (part of the brain stem) and receives input from the nucleus tractus solitarius and vagus nerve. The vomiting centre is in charge of causing the vomiting reflex (MacDougall & Sharma 2020; Athavale, Athavale & Roberts 2020).

There are specific neurotransmitters that induce the action of vomiting. These include histamine, dopamine, serotonin, acetylcholine and neurokinin (Athavale, Athavale & Roberts 2020).

Prior to vomiting, the individual may display:

  • Nausea
  • Pallor
  • Cold sweat
  • Increased heart rate
  • Increased saliva production (to protect the teeth from stomach acid).

(Queensland Health 2018)

During the vomiting process, muscles in the diaphragm, chest wall and abdomen begin to contract, forcing the stomach contents upward. While this occurs, the epiglottis closes to ensure that the stomach contents cannot enter the trachea or lungs (Queensland Health 2018).

Causes of Nausea and Vomiting

There are many potential causes of nausea and vomiting, including:

  • Gastroenteritis
  • Migraine
  • Intense pain
  • Motion sickness
  • Certain medicines (e.g. nonsteroidal anti-inflammatories, oral contraceptives, narcotics, antibiotics)
  • Alcohol
  • Stress
  • Bowel obstruction
  • Cancer treatments (e.g. chemotherapy)
  • Gallbladder inflammation
  • Viral or bacterial infections (including COVID-19)
  • Food poisoning
  • Pregnancy
  • General anaesthesia
  • Appendicitis
  • Dizziness
  • Vertigo
  • Ear infection
  • Fever
  • Heart attack
  • Anxiety disorders
  • Irritable bowel syndrome
  • Allergies and anaphylaxis
  • Labyrinthitis
  • Certain cancers
  • Changes to water and food while travelling
  • Hyperglycaemia
  • Hypoglycaemia
  • Hypovolaemia
  • Hypotension
  • Kidney infection
  • Kidney stones.

(Healthdirect 2019, 2021b; Mayo Clinic 2020)

Please note that this is not an exhaustive list of all potential causes.

Complications of Nausea and Vomiting

Rarely, nausea and vomiting may indicate a serious underlying condition such as appendicitis, meningitis, concussion or a brain tumour (Cleveland Clinic 2019).

If a client has had a fall or injury to the head, escalate care and call an ambulance.

Consult the client’s general practitioner if they are experiencing any of the following:

  • Vomiting that has persisted for longer than two days
  • Dehydration
  • Inability to keep down fluids for the past 12 hours
  • Green vomit (indicating the presence of bile)
  • Abdominal pain
  • Diabetes (as comorbidity).

(Healthdirect 2021a)

Seek emergency medical attention if a client is experiencing any of the following symptoms in addition to vomiting:

  • Chest pain
  • Severe abdominal pain or cramps
  • Blurry vision
  • Confusion
  • Stiff neck accompanied by a high fever
  • Faeces present in vomit
  • Rectal bleeding
  • Blood present in vomit (resembling coffee granules)
  • Sudden, severe headache
  • Suspected poisoning.

(Healthdirect 2021a; NHS Inform 2020)

Persistent Nausea and Vomiting

nausea vomiting persistent vomiting
Persistent vomiting may lead to dehydration.

Persistent nausea may be highly distressing and cause feelings of exhaustion or depression (Knott 2020).

Persistent vomiting may lead to issues such as:

  • Dehydration
  • Electrolyte imbalance
  • Damage to tooth enamel due to erosion from stomach acid
  • Bleeding caused by tears to the oesophageal lining
  • Malnourishment, compromised immunity and weight loss caused by difficulty replacing essential nutrients.

(Knott 202; Queensland Health 2018)

Symptoms that indicate dehydration include:

  • Reduced urine output
  • Dark urine
  • Sunken eyes
  • Dry mouth and tongue
  • Fatigue
  • Headache
  • Confusion
  • Rapid heartbeat
  • Cool peripheries/extremities
  • Low blood pressure
  • Irregular heartbeat
  • Muscle cramping
  • Delirium or a change in cognition.

(Healthdirect 2021a; NHS Inform 2020; VIC DoH 2018)

Treating Nausea and Vomiting

Start Course: Nausea and Vomiting Treatment Options

If a client is experiencing nausea or vomiting:

  • Consider administering medicines such as antacids or antiemetics
  • Provide clear fluids such as water, herbal tea, diluted juice or frozen drinks and ensure the client takes frequent small sips to prevent dehydration
  • Consider giving oral rehydration fluids
  • Avoid giving caffeinated beverages such as coffee or soft drinks
  • Encourage the client to nibble on light, bland foods that are easily digestible (e.g. dry crackers, rice, plain bread)
  • Encourage the client to sit down or lie with their head elevated
  • Discourage brushing teeth immediately after a vomiting episode, as this may cause stomach acid to erode the tooth enamel
  • Encourage rest
  • Avoid providing solid foods until vomiting has stopped
  • Encourage the client to eat normally, if possible
  • Avoid giving the client very fatty, spicy, greasy or sweet foods
  • Discourage meal skipping
  • Encourage slow eating and drinking
  • Discourage physical activity after eating
  • Provide the client with small, regular meals
  • Provide foods from all food groups (that the client is able to tolerate) to ensure the client receives adequate nutrition.

(Healthdirect 2021a, b; Cleveland Clinic 2019; Harvard Health Publishing 2019; NHS Inform 2020; Appledore Dental Clinic 2020)

Preventing Nausea and Vomiting

nausea vomiting prevention hand hygiene

The best way to prevent nausea and vomiting is to maintain effective hygiene practices, as this will reduce the risk of spreading infections that cause these symptoms (Healthdirect 2021a).

Refer to the following articles for comprehensive information on maintaining effective hygiene:

Strategies for preventing nausea and vomiting that are unrelated to infection include:

  • If possible, avoiding exposing clients to nausea triggers such as strong smells or certain foods
  • Encouraging clients to eat small meals regularly and avoid complete stomach emptying
  • Avoiding providing foods that are difficult to digest
  • Serving foods at room temperature to clients who are nauseated by the smell of hot foods
  • Ensuring clients consume adequate water throughout the day
  • Encouraging clients to rest with their head elevated after eating
  • Encouraging clients to eat and drink at separate times
  • Discouraging clients from standing up or getting out of bed suddenly
  • Taking precautions for motion sickness if it is expected.

(Healthdirect 2021b; Cleveland Clinic 2019)

Additional Resources


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