Cyclic vomiting syndrome (CVS) is a pattern of repeated bouts of severe nausea and vomiting usually interrupted by even longer periods without symptoms. Symptoms occur suddenly and may last for hours or even days. In the worst cases, patients may vomit between five and 12 times an hour for up to 10 days.

CVS unfolds in four phases:

• Prodrome. A patient experiences abdominal pain that may last for anywhere from a few minutes to several hours.
  
  
• Episode. The patient experiences nausea and vomits repeatedly. The patient may also gag and experience listlessness and have unusual skin paleness.
  
  
• Recovery. During this phase, the patient ceases vomiting and nausea subsides.
  
  
• Symptom-free interval. This is the phase between episodes in which no symptoms of nausea or vomiting are present.

Children are diagnosed with CVS more than any other age group. It is most likely to affect girls between the ages of 3 and 7 years. Adults can also have this condition, and tend to experience episodes that are less frequent but more intense than those of children with CVS. In children, CVS often subsides before the teenage years. Some children with CVS develop migraines later in life.

The exact cause of CVS remains unknown. However, there appears to be a relationship between migraines and CVS and some research suggests that the condition is also related to panic attacks (sudden episodes of fear and anxiety). Infections are the most common trigger of symptoms, but children are also susceptible to vomiting cycles after experiencing emotional stress or high levels of excitement. Eating too much food or certain types of food also tends to cause symptoms in some patients.

Diagnosis of CVS is complicated by the fact that many other illnesses and disorders can sometimes cause vomiting. CVS cannot be diagnosed until these other disorders – including stomach flu and food poisoning – are ruled out.

Cyclic vomiting syndrome (CVS) is a condition in which a patient experiences repeated bouts of severe nausea and vomiting interrupted by even longer periods without symptoms. A typical cycle occurs suddenly and may last for hours or even days. A bout of CVS then often disappears as quickly as it began.

CVS unfolds in four phases:

• Prodrome. During this phase, a patient experiences abdominal pain that may last for anywhere from a few minutes to several hours. This is typically a warning that another cycle of nausea and vomiting is going to occur. In some cases, the prodrome unfolds gradually enough that medication can be taken to prevent vomiting. However, in other cases vomiting begins too quickly to employ prevention methods.
  
  
• Episode. The patient experiences nausea and vomits repeatedly during this phase. In the worst cases, patients may vomit between five and 12 times an hour for up to 10 days. Patients may not be able to eat, drink or take any medications without vomiting.
  
  
• Recovery. The patient ceases to vomit and nausea subsides. The patient’s energy and appetite also return.
  
  
• Symptom-free interval. This is the phase between episodes in which no symptoms of nausea or vomiting are present.

The exact cause of cyclic vomiting syndrome (CVS) remains unknown. However, there appears to be a relationship between migraines and CVS. These conditions are characterized by severe symptoms that begin quickly and end just as suddenly. In addition, they tend to share the same types of triggering events, and a family history of migraines has been associated with CVS.  

Some research also suggests that CVS is related to panic attacks. Panic attacks are sudden episodes of fear and anxiety that usually last for between 10 minutes and 30 minutes and cause symptoms such as a racing heartbeat, heavy perspiration and shortness of breath.

Certain conditions or events are closely associated with bouts of vomiting. Infections are the most common trigger, but children are also susceptible to vomiting cycles after experiencing emotional stress or high levels of excitement (such as before a trip to the circus or a vacation). Colds, stomach flu, allergies and sinus problems can all trigger bouts of vomiting as well.

Some patients report that eating certain foods can lead to episodes of vomiting. Chocolate and cheese are two foods often mentioned. The additive monosodium glutamate (MSG) is a trigger for some patients. In addition, eating too much food or eating before bedtime may trigger vomiting. Other triggers include extreme fatigue, hot weather, menstruation and motion sickness.

Females are slightly more likely than males to have CVS. Children are diagnosed with CVS more than any other age group. It is most likely to affect girls between the ages of 3 and 7 years. However, CVS in children often subsides before the teenage years. Adults can also have this condition, and tend to experience episodes that are less frequent but more intense than those associated with childhood CVS. 

Symptoms of cyclic vomiting syndrome (CVS) include severe nausea and vomiting, gagging, exhaustion and listlessness, and unusual paleness of the skin. At its worst, CVS may cause a patient to vomit between five and 12 times an hour, and patients may appear to be so listless that they seem almost unconscious or in a “waking coma.” Episodes may resolve within a single day, or may last for up to 10 days.

Other symptoms associated with CVS include:

• Abdominal pain
• Diarrhea
• Dizziness
• Drooling
• Excessive thirst
• Fever
• Headache
• Sensitivity to light

Patients who have CVS tend to have symptoms that are similar in nature and intensity from one episode to another. In addition, symptoms tend to start at the same time of day (usually at night or first thing in the morning).

Repeated cycles of vomiting can lead to long-term complications, including:

• Hematemesis. Irritation that causes the esophagus (tube between the mouth and stomach) to bleed.
  
  
• Mallory-Weiss tear. Tearing of the lower end of the esophagus.
  
  
• Peptic esophagitis. Injury to the esophagus resulting from stomach acid in vomit.
  
  
• Tooth decay. Acid in vomit can corrode tooth enamel.

Before diagnosing cyclic vomiting syndrome (CVS), a physician will perform a physical examination and compile a thorough medical history. A patient’s signs and symptoms and the pattern of cyclical vomiting are usually used to diagnose the disorder.

Diagnosis of CVS is complicated by the fact that many other illnesses, medications and disorders can sometimes cause vomiting. CVS cannot be diagnosed until these other disorders – including stomach flu and food poisoning – are ruled out. Gastroparesis or chronically slow stomach emptying may need to be excluded. It is often more difficult to pinpoint the events or situations that trigger bouts of CVS in adults than it is in children.

Researchers are currently developing an algorithm for CVS in children, which should help to more easily identify those at risk for the condition and reduce unnecessary diagnostic testing.

Preparing questions in advance can help patients and parents to have more meaningful discussions with physicians regarding their or their child’s treatment options. The following questions related to cyclic vomiting syndrome (CVS) may be helpful:

1. What signs and symptoms indicate that I might have CVS rather than another illness?
   
   
2. What other conditions might be causing my vomiting?
   
   
3. What are the long-term health risks posed by CVS?
   
   
4. What are my treatment options?
   
   
5. Will I require hospitalization for dehydration? How can I reduce the risk of dehydration?
   
   
6. Are there certain activities or foods that I should avoid to reduce my risk of vomiting?
   
   
7. How can I prevent future bouts of vomiting?
   
   
8. Will my child develop migraines later in life?
   
   
9. My child tends to experience episodes of CVS after stressful and exciting occasions. How can I help my child deal with the emotions that trigger CVS?
   
   
10. How can I help my child through a bout of CVS?