what are the main causes of nausea?
['Motion sickness or seasickness.', 'Early stages of pregnancy (nausea occurs in approximately 50%-90% of all pregnancies; vomiting in 25%-55%)', 'Medication-induced vomiting.', 'Intense pain.', 'Emotional stress (such as fear)', 'Gallbladder disease.', 'Food poisoning.', 'Infections (such as the "stomach flu")']