What Causes Vomiting?

Vomiting is the involuntary and forceful expulsion of the stomach contents through the mouth. It is generally seen together with nausea, but in some people it can occur without nausea.

It is not a disease in itself. It can develop from causes as varied as a simple stomach and bowel infection, the medicines being taken, migraine, disorders of gastric emptying, or bowel obstruction.

A significant proportion of short-lived vomiting settles on its own. Vomiting that recurs continually, that prevents fluids from being taken, or that is accompanied by alarm symptoms should nevertheless have its cause investigated.

Vomiting has many causes, and on its own it does not mean cancer.

What are the commonest causes of vomiting?

Stomach and bowel infections

This is one of the common causes of vomiting of acute onset.

In viral or bacterial gastroenteritis, the vomiting may be accompanied by:

• Diarrhoea
• Abdominal pain and cramps
• Fever
• Weakness

Food poisoning can also cause nausea and vomiting of sudden onset.

Can diseases of the stomach cause vomiting?

Yes.

Conditions such as gastritis and ulcer can give rise to nausea and vomiting.

In functional dyspepsia it is more usual to see early satiety, fullness after meals and upper abdominal symptoms; where there is marked or persistent vomiting, other causes also need to be investigated.

Can gastroparesis cause vomiting?

Yes.

In gastroparesis the emptying of the stomach is delayed although there is no mechanical obstruction at its outlet.

Patients may have:

• Early satiety
• Prolonged fullness after meals
• Bloating
• Nausea
• Vomiting

Vomited food that was eaten hours earlier and is insufficiently digested may suggest that gastric emptying is delayed.

Diabetes and certain medicines are among the conditions that can cause gastroparesis.

Does obstruction at the outlet of the stomach cause vomiting?

A narrowing or obstruction developing where the stomach opens into the duodenum can prevent food from passing on.

In this situation there may be:

• Recurrent vomiting after meals
• Early satiety
• Fullness in the stomach
• Weight loss

in particular.

In such a situation, mechanical obstruction needs to be excluded.

Does vomiting occur in bowel obstruction?

Yes, and it is an important situation.

Where the bowel contents cannot pass on, there may be:

• Marked swelling of the abdomen
• Cramping or severe abdominal pain
• Vomiting
• An inability to pass wind or stool

Vomiting + marked abdominal swelling + an inability to pass wind or stool together requires urgent assessment for bowel obstruction in particular.

Can diseases of the gallbladder and pancreas cause vomiting?

Yes.

In gallstones and diseases of the bile ducts, nausea and vomiting can be seen together with abdominal pain.

In acute pancreatitis, marked nausea and vomiting generally accompany severe pain that begins in the upper abdomen and may radiate to the back.

Can medicines cause vomiting?

A great many medicines can give rise to nausea and vomiting.

Certain:

• Antibiotics
• Painkillers
• Medicines used in cancer treatment
• Iron preparations
• Opioids
• Certain medicines used in the treatment of diabetes and obesity

can cause nausea and vomiting.

Where symptoms develop after starting a new medicine or increasing a dose in particular, the medicines being taken should be reviewed.

Do not stop medicines you take regularly without consulting your doctor.

Does vomiting always come from the stomach?

No.

Vomiting can also be seen in diseases outside the digestive system.

For example:

• Migraine
• Diseases of the inner ear and the balance system
• Pregnancy
• Certain infections
• Metabolic disorders
• Kidney disease
• Certain neurological diseases

can cause vomiting.

For this reason it is not right to regard recurrent vomiting simply as “a stomach upset”.

Does the appearance of the vomit matter?

Yes.

What the vomit contains can give important clues about the cause.

Vomiting blood

Bright red blood, or dark material resembling coffee grounds, may be a sign of bleeding in the upper digestive tract.

This requires medical assessment.

Yellow or green vomit

Vomit containing bile may be yellow-green in colour.

On its own it does not make the diagnosis of any particular disease. Where it occurs together with severe abdominal pain and abdominal swelling in particular, causes such as bowel obstruction should be assessed.

What is the most important danger of persistent vomiting?

The body can lose water and electrolytes through vomiting.

This can result in:

• A dry mouth
• Excessive thirst
• Dizziness
• Weakness
• A reduction in the amount of urine
• Palpitations

Long-standing vomiting can cause disturbances of potassium and other electrolytes, and can affect kidney function.

What can be done during vomiting?

In short-lived and mild vomiting the most important aim is to prevent loss of fluid.

If the person can tolerate it, the following may help:

• Taking fluids in small amounts at frequent intervals
• Making use of suitable oral rehydration solutions where required
• Returning to eating in small portions as the vomiting settles
• Cutting down very fatty and heavy foods temporarily

Where vomiting is persistent and no fluid at all can be kept down, however, it is not right to wait at home.

Can anti-sickness medicines be used?

They can be used where required, but the treatment is not the same for every case of vomiting.

Suppressing the vomiting does not remove the underlying cause. In situations such as bowel obstruction, gastrointestinal bleeding or serious infection, the underlying disease needs to be treated.

For this reason, in recurrent vomiting in particular, the cause should be established rather than medicines being used indiscriminately.

When should a doctor be consulted?

Vomiting should be assessed if it:

• Recurs
• Lasts longer than a few days
• Prevents eating or the taking of fluids
• Leads to weight loss
• Occurs continually after meals
• Occurs together with early satiety
• Is newly started and cannot be explained

When is urgent assessment required?

Medical help should be sought without delay if any of the following is present:

• Vomiting blood, or vomit that looks like coffee grounds
• Severe or steadily increasing abdominal pain
• Marked swelling of the abdomen together with an inability to pass wind or stool
• Being unable to take fluids because of persistent vomiting
• Marked thirst, or a serious reduction in the amount of urine
• Fainting or a change in consciousness
• A severe, newly started headache with neurological symptoms
• High fever with a marked deterioration in general condition

How is the cause of vomiting investigated?

The doctor first assesses how long the vomiting has been going on, its relationship to meals, the character of the vomit, whether there is abdominal pain or diarrhoea, and the medicines being taken.

Depending on the patient’s condition:

• Blood and urine tests
• A pregnancy test
• Ultrasound
• Gastroscopy
• Computed tomography
• Gastric emptying studies
• Other investigations as required

can be carried out.

Not every patient with vomiting needs gastroscopy or a scan. The investigations are chosen according to the clinical findings.

Remember

Vomiting is not a disease; it is a symptom.

Most acute vomiting arises from short-lived causes. Vomiting blood, being unable to take any fluid, severe abdominal pain, and an inability to pass wind or stool together with abdominal swelling are nevertheless important alarm symptoms.

In recurrent or long-standing vomiting the aim is not merely to stop the vomiting, but to establish its cause.