Why do you vomit with sinus and have nausea?

Vomiting with sinus issues often occurs due to the body's response to inflammation and infection, which can affect the vestibular system and lead to nausea. The buildup of mucus can also lead to post-nasal drip, irritating the stomach and triggering vomiting. Additionally, sinusitis can cause headaches and general malaise, further contributing to feelings of nausea. Overall, the interconnectedness of the respiratory and gastrointestinal systems can explain these symptoms.