While a number of side effects have been associated with sublingual immunotherapy, serious adverse effects are very rare (about 1.4/100000 doses), and there has not been a reported fatality. There have been a small number of reports of anaphylaxis. The majority of side effects are ‘local’ and usually resolve within a few days. They include swelling of the mouth, tongue or lip, throat irritation, nausea, abdominal pain, vomiting, diarrhea, heartburn, and uvular edema. It is not yet clear if there are any risk factors that might increase a person's susceptibility to these adverse effects. Sublingual immunotherapy appears to be better tolerated than subcutaneous immunotherapy and causes fewer side effects. The safety of sublingual immunotherapy has not been studied extensively in people with chronic immunodeficiency or autoimmune disorders.