Cyclic vomiting syndrome causes bouts of severe nausea and vomiting that can last for days. The disorder, which has no known cause, may affect as many as one in 50 children. Once thought to affect primarily girls, cyclic vomiting syndrome is now believed to affect boys and girls equally.

Symptoms typically begin between the ages of 3 and 7 years. Children tend to outgrow cyclic vomiting syndrome when they are teenagers. While the disorder occurs most often in children, cyclic vomiting syndrome can begin at any age. Adult episodes tend to occur less often than they do in children, but they usually last longer.

Cyclic vomiting syndrome appears to be linked to migraines in some cases. Treatment with migraine medications often helps.

Cyclic vomiting syndrome causes severe vomiting, nausea and gagging — sometimes as often as 12 times an hour. Episodes in children generally last only a day or two, but adults can have symptoms for almost a week. Adults tend to have about four episodes a year, while children have about 12. Episodes typically begin at night or first thing in the morning.

Other common symptoms include pallor and exhaustion. Some people also become sensitive to light and may develop:

• Headache
• Fever
• Dizziness
• Diarrhea
• Abdominal pain

The cause of cyclic vomiting syndrome is unknown, but the bouts of vomiting that characterize the condition can be triggered by:

• Colds, allergies or sinus problems
• Emotional stress or excitement
• Foods such as chocolate or cheese
• Overeating, or eating right before going to bed
• Hot weather or physical exhaustion
• Menstruation
• Motion sickness

Many children who have cyclic vomiting syndrome have a family history of migraines or begin having migraines themselves when they get older. Abdominal migraines — a type of migraine more common in children — cause abdominal pain but not the severe vomiting associated with cyclic vomiting syndrome.

A family history of depression, irritable bowel syndrome and hypothyroidism also has been linked to cyclic vomiting syndrome.

To be diagnosed with cyclic vomiting syndrome, a person must have experienced at least two episodes of intense nausea and unremitting vomiting or retching — lasting hours or days. These episodes must be separated by weeks or months of symptom-free intervals.

There is no specific test that will confirm the diagnosis of cyclic vomiting syndrome. Doctors must rule out other conditions that can produce vomiting, such as:

• Inner ear problems
• Metabolic disorders
• Intestinal blockage
• Brain tumors
• Pregnancy

Cyclic vomiting syndrome can cause the following complications:

• Dehydration. Excessive vomiting causes the body to lose water quickly. This can also lead to an imbalance in electrolytes, the important salts needed to keep the body working properly. In severe cases, hospital treatment is required.
• Injury to the esophagus. The stomach acid that comes up with the vomit can damage the tube that connects the mouth and stomach (esophagus). Sometimes the esophagus becomes so irritated, it bleeds.
• Tooth decay. The acid in the vomit can corrode tooth enamel.

There is no cure for cyclic vomiting syndrome. Severe bouts may require hospitalization for administration of intravenous fluids. Anti-nausea drugs and sedatives also may be delivered intravenously.

In many cases, the same types of medications used for migraines often help stop or even prevent episodes of cyclic vomiting. These medications include:

• Tricyclic antidepressants, such as amitriptyline and nortriptyline
• Triptans, such as sumatriptan (Imitrex) and zolmitriptan (Zomig)
• Analgesics, such as ibuprofen (Motrin, Advil)

Many people know what triggers their cyclic vomiting episodes. Avoiding those triggers can reduce the frequency of episodes. However, it is easier to pinpoint triggers in children than it is in adults.

If episodes occur more than once a month or require hospitalization, daily preventive medicine is typically recommended. The most commonly used drugs to prevent cyclic vomiting episodes include amitriptyline and propranolol (Inderal).

People with cyclic vomiting syndrome generally need to get adequate sleep. Once vomiting begins, it may help to stay in bed and sleep in a dark, quiet room.

When the vomiting phase has stopped, it's very important to drink water and replace lost electrolytes. Some people feel well enough to resume normal eating immediately, while others need to start with clear liquids and then graduate up to solid food.