Cyclic Vomiting Syndrome

What is cyclic vomiting syndrome?

Cyclic vomiting syndrome (CVS) is a condition in which a person has attacks of severe nausea and repeated vomiting at intervals.

Its most characteristic feature is that the vomiting is not continuous. An attack begins, lasts hours or sometimes several days, and then settles. Between attacks the person may be entirely or largely well.

The condition is better known in children but is seen in adults too and may begin in adult life.

What causes it?

The exact cause of cyclic vomiting syndrome is not yet fully known.

It is now thought that the condition is not simply a problem of the stomach; communication between the brain and the digestive system, the autonomic nervous system, the stress response and certain neurohormonal mechanisms are believed to play a part together.

There is a strong association between CVS and migraine. A history of migraine in the person or in the family may support the diagnosis.

But CVS is not a psychological illness. Stress and anxiety may trigger or worsen an attack in some people, but they are not accepted as the sole cause of the condition.

How do attacks develop?

The condition generally runs in successive phases.

1. The phase before an attack

The person may sense that an attack is coming.

There may be nausea, loss of appetite, abdominal discomfort, weakness, sweating or restlessness.

Some patients recognise these symptoms from earlier attacks.

2. The vomiting phase

Severe nausea and repeated vomiting begin.

Vomiting may recur at short intervals and the person may struggle to take food or fluids.

An attack may last hours, or in some patients several days.

3. The recovery phase

The vomiting gradually lessens and stops.

Appetite returns and the person begins to take fluids and food again. Weakness may persist for a while.

4. The phase between attacks

This is one of the distinguishing features of CVS.

The person returns entirely or largely to normal life until the next attack.

What can trigger an attack?

Triggers vary from person to person.

Those commonly reported include:

• Lack of sleep,
• Intense stress or excitement,
• Going without food for a long time,
• Excessive physical tiredness,
• Certain infections,
• Travel,
• Menstruation,
• Certain foods in some people.

The same triggers are not seen in every patient.

Keeping an attack diary may therefore help a person to recognise their own triggers.

How is the diagnosis made?

There is no special blood test, endoscopy or imaging method that shows cyclic vomiting syndrome on its own.

The diagnosis rests first on the characteristic pattern of the attacks.

It is also necessary to be sure that no other disease that could cause similar recurrent vomiting is present.

Where they are thought necessary:

• Blood and urine tests,
• Gastroscopy,
• Imaging of the abdomen,
• Metabolic and hormonal investigations,
• Neurological assessment

may be carried out.

Not every patient needs all of these tests. The investigations are decided according to the person’s age, history, examination and accompanying symptoms.

What else can it be confused with?

Recurrent vomiting has many causes.

Gastroparesis, obstruction of the bowel, certain metabolic and hormonal diseases, diseases of the central nervous system, drugs and other digestive diseases can produce similar complaints.

In people who use cannabis regularly or heavily in particular, cannabinoid hyperemesis syndrome should also be considered.

This distinction matters, because the treatments differ.

How is it treated?

Treatment has two separate aims:

To stop an attack or reduce its severity, and to prevent new attacks from arising.

During an attack

Treatment is begun as early in the attack as possible.

According to the patient’s condition:

• Drugs to reduce nausea and vomiting,
• In migraine-type attacks, drugs directed at migraine in suitable patients,
• Fluid and electrolyte support,
• Intravenous fluid treatment where needed

may be given.

A dark, quiet environment may help some patients feel more comfortable.

Hospital treatment may be needed in severe attacks.

To prevent attacks

Preventive treatment may be considered in patients with frequent or severe attacks.

In adults with moderate to severe CVS, amitriptyline is one of the most widely used first choices.

Alternative drugs such as topiramate or aprepitant may also be considered in suitable patients.

Which drug is used is decided taking account of the person’s age, other illnesses, the frequency of attacks and other medication.

Regular sleep, not going hungry for long periods and avoiding personal triggers are also important parts of treatment.

Is there a link with migraine treatment?

Yes.

Because of the close association between CVS and migraine, certain migraine drugs may be used both to prevent attacks and, in suitable patients, to stop an attack that has begun.

The link may be more marked in patients who have migraine themselves or in the family.

Is the condition dangerous?

CVS itself does not generally cause lasting damage to the stomach.

But severe and prolonged attacks of vomiting may produce:

• Serious fluid loss,
• Electrolyte disturbance,
• Deterioration in kidney function,
• Nutritional problems,
• Damage to the gullet from vomiting.

It is therefore important that severe attacks are treated in hospital where needed.

What is the course of the condition?

The course varies from person to person.

In some patients attacks become less frequent over time. In others they recur from time to time over years.

Making the right diagnosis matters particularly. Where CVS is not recognised, patients may present repeatedly to emergency departments with the same complaint and undergo a great many investigations.

Setting out a personal attack plan in advance can allow suitable treatment to be started early in an attack and reduce unnecessary procedures.

When is emergency help needed?

Emergency assessment is needed if fluids cannot be kept down because of the vomiting, or if any of the following arises:

• Vomiting that does not stop,
• Marked fluid loss,
• A marked reduction in urine,
• Fainting or a change in consciousness,
• Severe or unusual abdominal pain,
• Vomiting of blood,
• High fever,
• New, serious neurological symptoms.

In a patient already diagnosed with CVS in particular, a picture markedly different from previous attacks means that it should not automatically be taken as a new CVS attack and that other causes should be investigated.

Currency: The information on this page was prepared for patients taking account of the 2025 European guideline on chronic nausea and vomiting and international recommendations on the diagnosis and treatment of cyclic vomiting syndrome.

This content is for general information. The assessment of recurrent attacks of vomiting and the treatment plan should be determined by a doctor.