A doctor will often suspect cyclic vomiting syndrome in a child when all of the following are present:

• At least five episodes over any time period, or a minimum of three episodes over a 6-month period
• Episodes lasting 1 hour to 10 days and happening at least 1 week apart
• Episodes similar to previous ones, tending to start at the same time of day, lasting the same length of time, and happening with the same symptoms and intensity
• Vomiting during episodes happening at least four times an hour for at least 1 hour
• Episodes are separated by weeks to months, usually with no symptoms between episodes
• After appropriate medical evaluation, symptoms cannot be attributed to another medical condition

Click here to learn more on how CVS is diagnosed:

https://www.niddk.nih.gov/health-information/digestive-diseases/cyclic-vomiting-syndrome/diagnosis