Motion sickness refers to a variety of symptoms that occur in response to motion or movement, as in a car, a boat, or some other type of vehicle. People experiencing motion sickness may feel dizzy and disoriented, and have trouble maintaining balance. Nausea and vomiting are also common symptoms. Some patients may experience a calming effect by ingesting small amounts of marijuana. However, some people may not notice any improvement to their motion sickness, and some may even experience more severe symptoms.