What Causes Motion Sickness?

Motion sick after a rollercoaster ride
Motion sickness. tanebeau/Getty Images

Motion sickness is frequently called travel sickness, car sickness, and even sea sickness, as it commonly occurs in people who are riding on a boat. The truth is that any form of motion can trigger this illness, including being on a swing and novelty rides at the carnival. If you've never experienced motion sickness, you are very lucky -- according to the Centers for Disease Control, all of us will eventually experience the illness if we are subjected to enough motion (although it takes more motion for some than others).

How Motion Sickness Occurs

Your inner ear is responsible for balance, a sense of spatial awareness (knowing where your body is in relationship to the environment), and maintaining equilibrium. The inner ear accomplishes this with the help of your eyes (your vision), and something called proprioception, which is basically the process by which your muscles, tendons, and nerves are able to work together to sense movement. Your inner ear, vision, and proprioception collectively make up the vestibular system. When you become dizzy, it's because one or more of these three smaller systems that make up the vestibular system is out of whack, or the three systems are not working together in harmony.

Motion can cause these systems to fall out of sync with one another. For example, if you are sitting in a restaurant on the inside of a cruise ship, your eyes will not tell your brain that you're moving because inside the ship it doesn't look like you are, but your body and inner ear can still sense the movement and relay the message to your brain.

Your visual senses will tell you that you are not moving while the rest of your vestibular system will tell your brain that you're in motion. The conflicting messages can cause the symptoms of motion sickness.

This is why some people only experience car sickness if they are sitting in the back seat, and their symptoms sometimes subside if they look out the window or are driving.

Looking out the window helps to keep your vestibular system in sync. Your inner ear and the rest of your body know that you are moving, and looking out the window helps ensure that your visual system also knows you're moving and relays the same message to your brain.

Symptoms of Motion Sickness

The symptoms of motion sickness can be mild or quite severe. Some people are more prone to motion sickness than others. For example, infants and toddlers rarely get motion sickness but kids aged 2-12 years are more susceptible. Pregnant women or those who experience migraines are also more likely to get motion sickness. Symptoms may include some or (if you're really unlucky) all of the following:

  • nausea
  • vomiting
  • dizziness
  • cold sweats
  • headache
  • yawning
  • malaise
  • dilated pupils in some people
  • a general feeling that something is not right or that you are unwell

Prevention and Treatment of Motion Sickness

You can prevent or minimize the symptoms of motion sickness without medication by:

  • sitting in the front seat or at least next to a window
  • avoiding reading while traveling in a car, plane or boat
  • avoiding spicy, greasy foods or large meals before traveling
  • focusing on something in the distance instead of something inside the vehicle
  • if possible, being the driver and not a passenger
  • for some people, drinking a beverage with caffeine may help
  • chewing fresh ginger, taking ginger as a tablet or other ginger preparations can speed up the rate at which your stomach empties and subsequently help with nausea and vomiting

Useful Medications For Treating Motion Sickness

You can buy many over-the-counter (OTC) medications for motion sickness, but in severe cases a prescription medication may be necessary. Many of these medications can cause drowsiness, and some should not be used in children, so make sure you read the package insert and talk to your doctor or pharmacist before deciding which to use.

Commonly used OTC medications include:

  • Dramamine (dimenhydrinate)
  • Benadryl (diphenhydramine) - while Benadryl does have anti-nausea properties, it may not be as effective as other medications
  • meclizine - this is the active ingredient in many OTC motion sickness medications and is less sedating than Dramamine for most people

Medications Available by Prescription

  • scopalamine
  • Reglan (metocloprimide)
  • Phenergen (promethazine)

You will find other "remedies" for sale at stores or online, but keep in mind that many have not been studied or proven useful for the treatment of motion sickness.

Sources:

American Academy of Otolaryngology - Head and Neck Surgery. Dizziness and Motion Sickness. Accessed: May 30, 2012 from http://www.entnet.org/HealthInformation/dizzinessMotionSickness.cfm

Audiology Awareness Campaign. Inner Ear Balance System. Accessed: May 30, 2012 from http://www.audiologyawareness.com/hearinfo_iebalance.asp

CDC. Motion Sickness. Accessed: August 31, 2015 from http://wwwnc.cdc.gov/travel/yellowbook/2016/the-pre-travel-consultation/motion-sickness

Medline Plus. Motion Sickness. Accessed: May 30, 2012 from http://www.nlm.nih.gov/medlineplus/motionsickness.html

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