Ear infection (otitis) symptoms may include nausea and vomiting. Pressure in the middle ear can cause balance issues, which lead to dizziness and nausea. Dizziness may include vertigo (a feeling the room is spinning), unsteadiness, faintness or fatigue and related nausea, according to the Mayo Clinic.
The inner ear holds the semicircular canals and other structures that work together to sense changes in gravity and motion. If an infection interrupts a part of this system, the central nervous system can receive inaccurate, confused or conflicting signals, leading to imbalance (as the brain tries to correct for the faulty signals) and accompanying stomach upset (including the vomiting reflex). The brain reacts to confused signals as if the body is under attack and seeks to clear the stomach of possible toxins.
Inner ear infections are most often caused by a virus. Symptoms can be sudden and severe, including an inability to concentrate and vomiting. Such infections often only affect one ear and may require medications to address the stomach issues during treatment of the infection itself.
The term neuritis is used when the virus causes inflammation of one part of the nerve that connects the ear and brain. It can cause dizziness, which may lead to stomach upset. Inflammation of the labyrinth is called labyrinthitis, a term used when both branches of the vestibulocochlear nerve are affected.
According to the Vestibular Disorders Association, long-term symptoms (of inner ear infection) can be treated with a type of physical therapy aimed at helping the brain compensate for the imbalances occurring in the ear. In such cases, the treatment often leads to more episodes of potentially stomach-upsetting dizziness and patients must be willing to work through the retraining despite these sensations for the therapy to succeed.
Drainage of the Eustachian tubes enters the back areas of the nasal tract and throat, where it may be expelled or swallowed. Drainage may include fluid, mucus and bacteria. Drainage occurring over a period of time can cause nausea, especially when the stomach is relatively empty. The same illness may cause both ear and digestive tract issues. One way this can happen is when drainage transmits the bacteria affecting the ear to the stomach.
Medications meant to help the body fight off infection (including antibiotics) may cause stomach upset as a side effect of their function.