The direct cause is a hypersensitivity of the vagus, the organ in the inner ear that is responsible for maintaining balance. It works by providing the brain with information about changes in body position.

In people who are predisposed to motion sickness, an excess of stimuli, especially when travelling with rocking (rhythmic rising and falling), causes 'information chaos'. Visual stimuli (rapidly shifting images outside the window) are an additional factor. The brain bombarded with an excess of stimuli reacts with nausea, vomiting and imbalance. Patients with motion sickness also often report a feeling of rapid heartbeat, salivation, increased sweating and significant weakness.

It is important to emphasise that motion sickness is not caused by any damage to the vagus, nor is it a 'disease' in the strict sense of the word.

Moving in a seagoing vessel or aircraft is not a natural way for humans to move. From the point of view of evolution and biology, our brain and vagus are not adapted to such stimuli, so the symptoms that occur when travelling by car, ship or plane are understandable and natural. Of course, preventive measures should be taken in people who are particularly hypersensitive, so that the inevitable journeys can be made in comfort.

Typical symptoms of motion sickness usually do not require medical advice because, as described above, the symptoms are a legitimate reaction of the vagus to the excess stimuli associated with travel. A visit to the doctor (preferably an ENT or neurologist) is required for very severe symptoms that do not resolve after typical home remedies.

In home management, it is important to follow certain rules in preparation for travel. Always sit facing forward. When given a choice of seats, sit where the sway will be least - in a bus NOT on the wheel axle, in an aeroplane preferably exactly where the wings attach. Do not overeat before travelling, mainly drink small amounts of non-carbonated drinks. In addition, symptoms are less in a semi-reclined position. Frequent breaks during the journey with a breath of fresh air are also beneficial (in a plane unfortunately difficult to do...).

As a prophylactic measure, one of the over-the-counter remedies to reduce motion sickness symptoms can be given. These include:

• Avioplant,
• Aviomarin,
• homeopathic Cocculine.

It is important to read the drug leaflet before taking them, as there are specific contraindications to their use.