In general, sneezing does not have a foul odor. In the following cases, patients may have a foul odor when sneezing: 1. Diseases of the nose, such as rhinitis, sinusitis, nasal tumors, nasal inversion papilloma, and malignant tumors of the nasal cavity, such as cancer or lymphoma, etc., with local corruption and infection, and the stimulation of inflammation in the nasal cavity, leading to a foul odor when sneezing. 2. Patients with diseases of the throat, such as chronic pharyngitis, tumors of the throat, local ulceration and erosion of the tumor, some patients with oral diseases, such as gingivitis, halitosis, nasopharyngeal cancer or adenoid hypertrophy of the nasopharynx and other related diseases, can cause patients to sneeze with a foul odor. 3. Some patients have chronic bronchitis, lung infections, pneumonia, asthma, lung abscesses, lung cancer and other related diseases, and the excrement in the lungs can smell bad when they sneeze. 4. Some patients have stomach diseases, such as chronic gastritis and Helicobacter pylori infection, and sneezing can be accompanied by odor caused by hiccups and acid reflux in the stomach. In conclusion, if a foul odor occurs when you burp, it can be observed if it occurs occasionally. If you have it every time, you need to go to the hospital for an examination to see what exactly is causing the odor.