Numerous diseases can cause lightheadedness and stomach sickness. According to the U.S. National Library of Medicine and the National Institutes of Health, dizziness is lightheadedness, or the feeling of imminent fainting. Lightheadedness occurs when there is inadequate blood flow to the brain. It is sometimes accompanied by nausea or the urge to vomit, although lightheadedness and nausea may be stand-alone symptoms. When they occur together, lightheadedness and nausea may signal an underlying disease.
Acute Mountain Sickness
Acute mountain sickness is a disease that can cause lightheadedness and nausea. According to the University of Maryland Medical Center, acute mountain sickness, or AMS, is an illness that can affect mountain climbers, hikers, skiers or travelers at altitudes greater that 8,000 feet above sea level. AMS is caused by reduced air pressure and decreased oxygen concentrations at higher elevations, and symptoms can range from mild to severe, affecting a person's nervous system, lungs, muscles and heart. Common symptoms include headaches, fatigue, nausea, dizziness and poor sleep, and physical exertion typically makes symptoms worse. The medical center notes that the likelihood of experiencing AMS increases the faster a person ascends and that symptoms often appear within six to 10 hours after a rapid ascent and resolve in one to two days.
Brain cancer is a disease that can cause lightheadedness and stomach sickness. The National Brain Tumor Society states that a brain tumor that occupies space within the skull can impair normal brain function and that the space-occupying lesion can increase brain pressure, shift the brain or force it against a person's skull and damage brain tissue and nerves. According to the NBTS, a brain tumor's location dictates the symptoms a person experiences. While the tumor's location influences a person's symptoms, common brain tumor-related complaints include new seizures in adults, the gradual decline of motor and sensory function in a person's arm or leg, loss of balance, loss of vision, double vision, difficulty speaking, confusion or disorientation, dizziness or lightheadedness and nausea or vomiting. The NBTS notes that nausea and vomiting may be most severe in the morning.
According to the National Institute on Deafness and Other Communication Disorders, a division of the National Institutes of Health, Meniere's disease is named after the French physician Prosper Meniere who first described the syndrome. It is an abnormality of the inner ear that causes numerous symptoms. The institute states that Meniere's disease--which typically affects only one ear and arises suddenly--is characterized by spontaneous bouts of vertigo that cause lightheadedness, nausea, vomiting and sweating. Other symptoms associated with Meniere's disease include tinnitus or ringing in the ears, hearing loss and pressure in the involved ear, along with headaches, abdominal discomfort and diarrhea, to a lesser degree. The institute notes that a person's hearing recovers between bouts of Meniere's disease but typically becomes worse overall with time.