When a person suddenly experiences severe nausea, vomiting, and stomach pain lasting one or two days, or even longer, they may suspect food poisoning or a gastrointestinal virus. However, if this occurs several times a year, it could be a sign of cyclic vomiting syndrome (CVS), an under-recognized condition that affects approximately 0.04% to 1.9% of the French population. In July, the American Gastroenterological Association (AGA) published new clinical guidelines to help doctors and their patients recognize the signs and symptoms of cyclic vomiting syndrome, also known as CVS. CVS is a chronic disease linked to an interaction between the gut and the brain and is characterized by recurrent episodes of nausea, vomiting, and retching, separated by periods without symptoms. "We are increasingly recognizing that this condition is more common than previously thought," says David Levinthal, a gastroenterologist and neuroscientist, director of the Neurogastroenterology and Motility Center at the University of Pittsburgh Medical Center. "It is not a condition that many gastroenterologists think about. There are many patients who suffer and are neither diagnosed nor treated." Christopher Vélez, a gastroenterologist and associate director of the Advanced Studies Program in Gastrointestinal Motility and Functional Diseases at the Massachusetts General Hospital Center for Neurointestinal Health in Boston, United States, explains that the condition is not a priority in medical education. "It is a bit like an abdominal migraine, a series of abnormal, uncontrollable, and neurologically mediated events. But as modern diagnostics do not allow us to identify what is wrong, sometimes it is considered psychological. And sometimes, patients are blamed for their symptoms, even though their quality of life is significantly affected." Although this syndrome can affect anyone, it is more common in children, women, and young adults. "A high percentage of children with this syndrome eventually outgrow it," says Anthony Lembo, a gastroenterologist and research director at the Digestive Disease Institute of the Cleveland Clinic in the United States. "For adults, it is not so simple." Among adults, anxiety, depression, and/or panic disorder often coexist with cyclic vomiting syndrome, as do migraines. And, like migraines, this syndrome is sometimes hereditary. In addition, the condition is slightly more common among people with epilepsy. "Each person has a different trigger," notes David Levinthal, and it can be difficult to identify triggers. Stress is a common trigger, as are lack of sleep, hormonal fluctuations related to the menstrual cycle, travel, motion sickness, periods of intense exercise, and physiological sources of stress such as illness or surgery. "If you have always had a sensitive digestive system, you are predisposed to this syndrome," says Christopher Vélez. "This makes you more sensitive to psychosocial triggers." Marissa Cohen began having regular episodes of cyclic vomiting syndrome at the age of two. Sometimes the vomiting was so abundant that she had nothing left in her stomach and bile would come up. After years of medical wandering, a diagnosis was made at the age of eight. "It was frustrating for my parents and me because we knew something was wrong, but we couldn't do much without an official diagnosis," reveals Marissa. Often, she ended up in the emergency room of a hospital where she received intravenous fluids and medication to stop the vomiting. The medication usually put her to sleep and she "woke up as if nothing had happened, it was so crazy," recalls the 21-year-old who is now. Most people with this syndrome often have two to four episodes per year. "There are more or less severe symptoms," specifies David Levinthal. According to the AGA, if a person has fewer than four episodes per year, each lasting less than two days, they are considered to have mild cyclic vomiting syndrome. If a person has four or more episodes per year, each lasting more than two days and requiring a visit to the emergency room or hospitalization, they are diagnosed as having moderate to severe cyclic vomiting syndrome. In order to rule out serious conditions such as obstruction, which could produce similar symptoms, an endoscopy and/or imaging tests, such as a CT scan or an upper gastrointestinal ultrasound, are sometimes requested. Blood tests, including a complete blood count and tests to measure levels of electrolytes, glucose, and liver enzymes in the blood, and urine tests are also part of the diagnosis. However, the diagnosis primarily relies on a thorough review of the medical history. "It is the recognition of a symptom pattern that constitutes the critical step," says Levinthal. Although CVS episodes can occur at any time, most of them occur early in the morning. People diagnosed with moderate to severe cyclic vomiting syndrome often take preventive medications, such as tricyclic antidepressants, such as amitriptyline or nortriptyline, or antiepileptic drugs, such as topiramate, zonisamide, or levetiracetam, on a daily basis. These medications do not eliminate episodes; the goal is to space them out and/or reduce their duration and severity. "One of the advantages of cyclic vomiting syndrome is that it allows you to choose the situation you are willing to live with," explains Vélez, referring to the fact that different treatments can be tested or combined. Many people with this condition experience prodromal symptoms, such as abdominal pain, headaches, mental fog, tremors, or anxiety, one or two hours before vomiting begins. "About 70% of patients can anticipate the onset of an episode," says David Levinthal. "If you take medication at the moment you feel it coming, you have a better chance of avoiding it." For people with mild cyclic vomiting syndrome or a moderate to severe form, treatments such as triptans, used for migraines, antiemetics, nausea medications such as ondansetron, promethazine, or prochlorperazine, or sedatives, such as alprazolam or diphenhydramine, are prescribed to try to stop the episode in its tracks. Since it can be difficult to swallow a medication during an episode, they can be taken through other routes: sublingually (under the tongue), via nasal spray, or as suppositories. Many people, like Marissa Cohen, use two or more medications to treat CVS. Today, she takes a tricyclic antidepressant every day to try to prevent episodes and has emergency medications on hand if she wakes up with nausea, for example. Although she goes to the emergency room less often than before, she still has one to five episodes of cyclic vomiting syndrome per year and must be careful with her travel, in case she needs medical assistance. "The hardest part," she says, "is that I don't really know what will trigger an episode." If people are unable to manage their symptoms or if they become dehydrated at home, they should go to the nearest hospital emergency room to receive fluids and intravenous treatment. Some people with this syndrome use cannabis, either recreationally or to relieve their symptoms. The problem is that it can be difficult to distinguish cannabinoid hyperemesis syndrome (CHS) from CVS. In the case of CHS, chronic cannabis use - more than four times a week for more than a year - can be associated with recurrent nausea, vomiting, and abdominal pain. This is why some gastroenterologists recommend that cannabis users with CVS abstain for three to six months to see if it makes a difference, explains Vélez. If they continue to have episodes of nausea and vomiting after that, CHS can be ruled out. To relieve symptoms, people with CVS often take warm baths or showers, sometimes several times a day. They are advised to sleep regularly, avoid prolonged fasting, and adopt stress management techniques such as meditation, the usefulness of which has been demonstrated. "There are many people who suffer from this disease and it is possible to treat it," emphasizes David Levinthal. "Patients need to make their voices heard, because help is possible."