Cyclic vomiting syndrome (CVS) is an uncommon, unexplained disorder of children and some adults that is characterized by recurrent, prolonged episodes of severe nausea, vomiting and prostration with no apparent cause. Vomiting occurs at frequent intervals (5-10 times an hour at the peak) for hours to 10 days (1-4 days most commonly.) The episodes tend to be similar to each other in symptoms and duration and are self-limited. The patient is generally well between episodes.
The illness is mostly found in children, but some adults also suffer.