How to prevent motion sickness: treatments and strategies

Motion sickness is not a 'sickness', but a normal physiological response to real, perceived, or anticipated movement and can be triggered by the movement of a car, train, aeroplane or amusement park ride. The symptoms of motion sickness tend to be limited to the duration of the motion experienced and include nausea and vomiting, dizziness, vertigo, cold sweating, disorientation, and fatigue.

Motion sickness can be debilitating and particularly interfere with functioning at work for those whose jobs entail motion. Motion sickness can be visually induced (when there is no real motion) in virtual environments, such as simulators, cinemas, and video games. 

Motion sickness indiscriminately affects air, sea, road and space travellers. All individuals (humans and animals) possessing an intact vestibular apparatus (inner ear 'balance centre') can get motion sickness given the right quality and quantity of provocative stimulation, although there are wide and consistent individual differences in the degree of susceptibility.

Although nausea is the hallmark symptom, motion sickness comprises a much broader syndrome. It includes a wide range of signs and symptoms, including cold sweating, pallor of varying degrees, increases in salivation, drowsiness, headache, and even severe pain, as well as nausea and vomiting.

What is Motion Sickness?

The sensory organs control the body’s sense of balance by signalling the brain as to the direction in which the body is pointing or moving and if it is standing still or turning.

These messages are relayed by:

• Inner ears - balance centre or vestibular system
• Eyes - visual system
• Skin pressure receptors - such as in those in the feet
• Muscle and joint sensory receptors - the proprioceptive system, which tracks what body parts are moving

All incoming sensory information is processed by the brain and spinal cord (central nervous system).

What causes Motion Sickness?

The cause of motion sickness is complex and not fully understood. Many theories of motion sickness have been proposed over the years.

The evolutionary theory – holds that motion sickness initially evolved as a response to poisoning. The notion is that when a toxic substance was ingested, nausea and vomiting resulted, inactivity would be induced, and symptoms would thus be attenuated because of reduced levels of ingested toxins.

The ecological theory of motion sickness is based on the hypothesis that motion sickness is caused by postural instability or a loss of postural control. The concept is that as postural instability increases, motion sickness will develop.

The sensory conflict theory - of motion sickness is the most widely accepted theory of motion sickness. Nearly all situations that elicit motion sickness involve some form of intersensory conflict. According to this theory, motion sickness results when the brain receives conflicting information about body movements from the visual (eyes) and vestibular receptors (inner ear) and the proprioceptive system (muscle and joint receptors).

An example of this type of intersensory conflict is when someone reads a book in the backseat of a moving car. The inner ears and skin receptors sense the motion, but the eyes only register the stationary pages of the book.

This conflicting information may cause the usual motion sickness symptoms of dizziness, nausea and vomiting.

The severity of motion sickness

Three key factors affect motion sickness development: a person’s sensitivity to stimulation, the rate of adaptation to stimulation, and the speed of resolution of elicited symptoms.

The range of sensitivity to motion sickness in the general population varies by about 10 to 1, and the rate of adaptation to stimulation also ranges from 10 to 1. By contrast, the speed of symptom resolution varies by 100 to 1.

The significance of these values is that susceptibility to motion sickness in the general population varies by about 10,000 to 1 – a vast range.

Motion sickness risk factors

Risk factors for the development of motion sickness include:

• Age - children aged 2–12 years are especially susceptible, but infants and toddlers are generally immune.
• Sex - women are more likely to have motion sickness, especially when pregnant, menstruating, or on hormones.
• Migraines - people who get migraine headaches are more prone to motion sickness, especially during a migraine.
• Medication - some medications can worsen the nausea of motion sickness
• Poor ventilation
• Anxiety or fear - both have been found to lower a person’s threshold for experiencing motion sickness symptoms.
• Alcohol - a drink is often thought to help calm the nerves, but in this case, it could upset the stomach further. A hangover for the next morning’s trip may also contribute to nausea.
• Genetic factors - research suggests that some people inherit a predisposition to motion sickness. This predisposition is more marked in certain ethnic groups; for example, Asians are more susceptible than other ethnic groups.
• Sleep deprivation - increases susceptibility to motion sickness.

What treatments are available for motion sickness?

Non-pharmacologic treatment

Prevention of motion sickness is much more effective than trying to “cure” symptoms once they have started. Both pharmacological and nonpharmacological treatments are more effective if applied before the motion stimulus. Patients should learn to identify situations that will lead to motion sickness and minimise the amount of unpleasant motion to which they are exposed while travelling. For example:

• Optimise position to reduce motion or motion perception—for example, driving a vehicle instead of riding in it, sitting in the front seat of a car or bus, or sitting over the wing of an aircraft. Cabin location on a cruise ship does not appear to influence the likelihood of motion sickness.
• Slow, intermittent exposure to the motion can reduce symptoms.
• Reducing sensory input by looking at the true visual horizon, tilting the head into turns, shutting the eyes, or lying prone.
• Nutritional tips to reduce motion sickness include avoiding fatty or spicy meals, staying well hydrated, drinking ginger ale, and eating small, frequent meals.

Among alternative therapies, acupressure, wristbands, and ginger have been proposed as safe motion sickness treatments.

Other potential remedies include biofeedback training and relaxation deep breathing techniques, and cognitive-behavioural therapy, modalities that have been tested on aeroplane pilots and were found to be helpful.

Music therapy

More recently, the use of relaxing and pleasant music has been proposed as a non-invasive and inexpensive counter-measure to visually induced motion sickness. During a visually induced motion sickness experience, persons who listened to music that they self-reported as 'pleasant', showed a significant reduction in motion sickness symptoms, with accompanying improved mood and emotion, compared with those who did not listen to 'pleasant' music.

Pharmacologic treatment

If non-pharmacological measures are insufficient, the use of pharmacological agents is advised. Please consult your healthcare professional for the right treatment for you, 

Hyoscine 

Hyoscine may be an effective drug for the prevention of motion sickness. It may help manage symptoms like nausea and vomiting by blocking the signals that travel from the balance-sensing part of your ear to your brain, which are responsible for making you feel sick when you have motion sickness.  

Antihistamines

Over-the-counter antihistamines are commonly used in the prevention and treatment of motion sickness and are the drugs of choice for motion sickness in children. There is no specific paediatric data for these drugs in motion sickness, and dosing has been extrapolated from studies done in adults. 

In Australia, sedating antihistamines have recently become prescription-only for children less than two years of age. Please consult your healthcare professional to ensure this product is right for you and your children. These medications appear to act by reducing the stimulation of the inner ear. The most common side effect is sedation. The newer non-sedating antihistamines, such as loratadine and cetirizine, do not cross the blood-brain barrier and are not effective against motion sickness. Antihistamines should be taken one hour before departure.

Examples of antihistamine medications effective in the prevention of motion sickness include:

• Dexchlorpheniramine
• Diphenhydramine 
• Promethazine 

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References

1. Takov, V., & Tadi, P. (2020). Motion Sickness. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK539706/
2. https://www.betterhealth.vic.gov.au/health/healthyliving/motion-sickness 
3. Lackner, J. R. (2014). Motion sickness: more than nausea and vomiting. Experimental Brain Research, 232(8), 2493–2510. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112051/
4. Saha, K. C., & Fife, T. D. (2014). Mal de débarquement syndrome. Neurology: Clinical Practice, 5(3), 209–215. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5764463/
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7. Motion Sickness | Travelers’ Health | CDC. (2022, January 28). Wwwnc.cdc.gov. https://wwwnc.cdc.gov/travel/page/motion-sickness
8. Keshavarz, B., & Hecht, H. (2014). Pleasant music as a countermeasure against visually induced motion sickness. Applied Ergonomics, 45(3), 521–527. https://pubmed.ncbi.nlm.nih.gov/23957932/
9. https://www.healthdirect.gov.au/medicines/brand/amt,35971011000036108/hyoscine-hydrobromide-dbl 
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