Although vomiting is not a classic symptom of asthma, the severe coughing fits that people with asthma suffer can sometimes trigger vomiting. Vomiting and asthma are linked, as muscle contractions in the chest from coughing can affect the stomach to the extent that the person throws up. Young children who may not be able to describe classic asthma symptoms like wheezing or chest tightness may display signs of the asthma by vomiting more than is usual for a child of that age.
Classic symptoms of asthma are primarily located in the chest. Wheezing, which is an abnormal sound that a person with asthma may make when breathing out, is one sign, although this may not be present in all people. The person may also feel a tightness or pain in the chest. Being unable to catch a breath is another indication a person has asthma. The repeated coughing that strikes asthma patients then has the potential to cause vomiting as an additional symptom.
Basically, when a person with asthma coughs uncontrollably, the muscles in the chest contract to the point where the stomach is affected. The diaphragm is a sheet of flat muscle that allows the lungs to expand while taking in air, and then contract when letting out breath. Coughing is a form of breathing, and if the coughing fit becomes too strong, the diaphragm presses the stomach to the point where the contents go back up into the throat and out as vomit.
Adults are generally able to describe abnormalities they feel when breathing, so children may be more likely to suffer repeated vomiting fits as a subtle sign of asthma. The medical term for throwing up after coughing is "posttussive emesis." Kids whose parents bring them to a doctor for unexplained vomiting, and who also have a history of many respiratory infections or gastroesophageal reflux, are more likely than other children to have asthma.
Vomiting and asthma are not necessarily related, however. Kids or adults with unusual vomiting, or vomiting fits that happen over and over, require medical advice in case other conditions are present. Even babies can have asthma, and display vomiting after coughing fits. Other medical problems like gastroesophageal reflux or sleep apnea, where breathing is interrupted during sleep, also appear to be related to vomiting and asthma. These conditions result from the same mechanism as vomiting and asthma, but the stomach contents, instead of making it out of the body as vomit, instead only reach up into the esophagus and cause irritation.