Doctor's Notes on Motion Sickness
Motion sickness is a common condition that occurs when the movement you see is different than what the inner ear senses. Motion sickness is not an illness in itself, but it is considered to be a form of dizziness. Motion sickness is common when traveling, such as seasickness (travel by boat), airsickness (plane), and carsickness (motor vehicles). Slow movement or movement in two different directions (such as up and down plus back and forth) at the same time are most likely to cause motion sickness. For reasons that are not completely understood, motion sickness is more common in people with migraines and vestibular migraines, in women (especially during menstruation or pregnancy), and among Asians and Europeans.
The main symptoms of motion sickness include nausea, vomiting, and dizziness. Other symptoms of motion sickness include sweating, increased salivation, and feeling unwell (malaise). Most of the time, motion sickness symptoms stop when the motion stops, but some people may have symptoms that last for up to a few days.
Motion Sickness Symptoms
Motion sickness can occur during any type of movement that is unintentional. Carsickness, seasickness, and air sickness are examples of motion sickness. Complex types of movement, especially slow movement or movement in two different directions (such as up and down plus back and forth) at the same time (commonly the movements of a boat in rough water) are most likely to cause motion sickness.
The primary symptom of motion sickness is nausea. Vomiting and dizziness may also occur.
Other common signs are:
- Increased salivation
- Ageneral feeling of discomfort and not feeling well (malaise)
The severity of motion sickness and how long it lasts varies, even in the same person on different days. Usually, the symptoms stop when the motion stops, although some people may experience symptoms for up to a few days after an episode of motion sickness. For example, after you get off of the boat or ship, you feel like you are moving even though you are not on the boat.
Ephedrine and some amphetamines have been used both to treat motion sickness and to counteract the sedating effects of other medical treatments. Studies have also shown a beneficial effect of caffeine when administered in combination with other medications for motion sickness.
Benzodiazepines have also been useful for some people with motion sickness, for example:
Anti-nausea (antiemetic) medications have been used to control nausea and vomiting after motion sickness has developed, for example:
Motion Sickness Causes
The cause of motion sickness is complex and not fully understood, but most experts believe that it arises due to conflicts in sensory input to the brain. The brain senses motion through different signaling pathways from the inner ear (sensing motion, acceleration, and gravity), the eyes (vision), and the deeper tissues of the body (proprioceptors), for example, muscles. When the body moves involuntarily, such as when riding in a vehicle, there may be conflict among these different types of sensory input to the brain. The sensory apparatus in the inner ear seems to be most critical in the development of motion sickness.
No tests can diagnose the cause motion sickness. Usually, it is diagnosed by your symtpoms and signs that occur during travel or during any form of passive motion.
A balance disorder is a condition that makes you feel unsteady or dizzy, as if you are moving, spinning, or floating, even though you are standing still or lying down. Balance disorders can be caused by certain health conditions, medications, or a problem in the inner ear or the brain.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.