What Causes Nausea?

Nausea is the unpleasant sensation of being about to vomit. It usually begins in the region of the stomach but can affect the whole body. It may occur together with vomiting, but not every episode of nausea ends in vomiting.

Nausea is not a disease in itself. It is a symptom that can arise from causes as varied as digestive-system diseases, the medicines a person takes, infections and migraine.

What are the commonest causes of nausea?

Diseases of the stomach and bowel

A significant proportion of nausea is related to the digestive system. The principal causes include:

• Gastritis
• Gastric and duodenal ulcer
• Gastro-oesophageal reflux
• Gastroenteritis
• Food poisoning
• Functional dyspepsia
• Gastroparesis (delayed emptying of the stomach)

Accompanying complaints such as abdominal pain, diarrhoea, bloating, early satiety or heartburn can help in determining the cause.

Diseases of the gallbladder and pancreas

Nausea that comes on particularly after meals may sometimes be related to diseases of the gallbladder and the bile ducts.

In acute pancreatitis, marked nausea and vomiting are generally seen together with severe upper abdominal pain.

Can medicines cause nausea?

Yes.

A great many medicines can cause nausea. Some antibiotics, painkillers, iron preparations and various other medicines are examples.

Where nausea appears after starting a new medicine, it may be useful for a doctor to review the medicines being taken.

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

Nausea in pregnancy

Nausea and vomiting are quite common in pregnancy, particularly in the early months.

Medical assessment is required, however, if vomiting becomes so severe and persistent that fluids and food cannot be taken.

Does nausea always come from the stomach?

No.

Nausea can also occur in diseases outside the digestive system.

For example:

• Migraine
• Diseases of the inner ear and the balance system
• Motion sickness
• Certain infections
• Disorders of blood sugar
• Kidney disease
• Certain neurological diseases
• Intense stress and anxiety

can cause nausea.

For this reason it may not be correct to treat long-standing nausea simply as “a stomach upset”.

Why does nausea occur in the morning?

Morning nausea does not have a single cause.

Pregnancy, reflux, certain diseases of the stomach, the medicines being taken and a range of metabolic or systemic conditions can all show themselves as morning nausea.

If it recurs continually, the cause needs to be investigated.

Why does nausea occur after eating?

Nausea that develops after meals may be related to many conditions, such as:

• Eating too much or too quickly
• Functional dyspepsia
• Gastroparesis
• Gastritis or ulcer
• Gallbladder disease

Where there is early satiety on very little food, prolonged fullness after meals and recurrent nausea in particular, problems with the emptying of the stomach may need to be assessed.

What helps nausea?

Treatment varies according to the cause of the nausea.

In short-lived and mild nausea, the following may help:

• Eating in small portions
• Avoiding very fatty and heavy meals
• Eating slowly
• Taking enough fluid
• Keeping away from foods noticed to increase the nausea

Anti-sickness medicines may be used in certain situations. In recurrent nausea, however, it is important to establish the underlying cause rather than merely suppressing the nausea.

When should a doctor be consulted?

If nausea does not settle within a few days, recurs often, or affects daily life and eating, it is appropriate to have it assessed.

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

• Severe or steadily increasing abdominal pain
• Persistent vomiting
• Vomiting blood, or vomit that looks like coffee grounds
• Black stools
• Marked weight loss
• Difficulty swallowing
• High fever
• Jaundice
• Severe headache or altered consciousness
• Marked thirst, a reduction in the amount of urine, or severe weakness
• Chest pain or breathlessness

How is the cause of nausea investigated?

A large number of tests is not needed for every case of nausea.

The doctor first assesses how long the nausea has been going on, its relationship to meals, whether there is vomiting, the accompanying symptoms and the medicines being taken.

Depending on the patient’s condition, blood tests, a pregnancy test, ultrasound, gastroscopy, gastric emptying studies or other investigations may be required.

Remember

Nausea is not a disease; it is a symptom.

Most nausea arises from short-lived and transient causes. Nausea that is long-standing or recurrent, or that is accompanied by alarm symptoms, should nevertheless have its cause investigated.