Approach

In almost all cases, motion sickness is easy to diagnose by history. The type of motion sickness is also easily distinguished by the type of motion and susceptibility and severity of symptoms. However, nausea is an extremely common symptom and the causes are extensive. A first episode may prompt medical attention. In all cases, other more serious causes should be excluded.

Symptoms

Motion sickness does not just present as nausea. This is often overlooked. Other important signs and symptoms include:[1][9]​​

  • Headache

  • Dizziness/light-headededness/unsteadiness

  • Epigastric discomfort

  • Vomiting or retching

  • Cold sweats

  • Dry mouth

  • Feeling of eye strain

  • Sleepiness

  • Sweating or cold sweats

  • Warmth or flushing

  • Generalised discomfort

  • Excessive salivation

  • Increased sensitivity to odours

  • Loss of appetite

  • Hyperventilation.

Distinguishing between motion sickness/visually induced motion sickness (VIMS) and motion sickness disorder (MSD)/visually induced motion sickness disorder (VIMSD)

Motion sickness and VIMS are normal physiological responses that can occur in most people. However, this response is classed as a disorder in individuals with particularly high susceptibility and symptom severity.[1]

At least five episodes of motion sickness or VIMS triggered by the same or similar motion stimuli is required to make a diagnosis of MSD or VIMSD. In both MSD and VIMSD, the lack of habituation to repeated exposures and the presence of behavioural or emotional responses, such as avoidance of triggering situations, are key distinguishing features.[1]

Any combination of motion sickness, MSD, VIMS, and VIMSD can co-occur, and susceptibility to one type of stimulus does not necessarily correlate with susceptibility to others.

History

Strong risk factors for motion sickness include the following:[1][4][9]​​[28][47][50]​​

  • Childhood age (2-12 years)

  • Female sex

  • Family history of motion sickness

  • History of migraine

  • Vestibulopathy

  • Spatial disorientation and space-motion discomfort

  • Unpleasant odours or visual stimuli

  • Conflicting sensory inputs (e.g., reading in car, tilting trains)

  • Psychological factors (e.g., anxiety)

  • Undertaking spatially loaded concurrent tasks such as looking at a map.

An important part of history-taking is ruling out other medical conditions. The most common differentials are:

  • Food poisoning or other gastric disturbance

  • Migraine

  • Inner ear disease

The patient should be asked about any associated symptoms:

  • Dizziness or vertigo

  • Pain

  • Hearing loss

  • Tinnitus

  • Visual disturbance

A neurological examination can assist differential diagnosis in rare cases when motion sickness is not the obvious condition.

Tests

Diagnosis is clinical; however, there are a range of questionnaires that can help predict susceptibility to motion sickness.[1]​ In addition, there are several physiological and biochemical tests that have been used in research settings to evaluate motion sickness, but these have limited clinical utility as symptoms are generally determined by symptoms on presentation.[18]

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