Motion Sickness

By Avinash Patil, MD

Overview

Motion sickness is a common problem, with enormous variability on who is susceptible and to what degree.  Symptoms can be mild such as simply a feeling of uneasiness, to severe vomiting, and dizziness. The most common symptom is nausea, derived from the Greek word for ship (naus), indicating this disorder’s tendency to affect seafarers.

Symptoms

Clinically, the first symptom usually described is feeling aware of one’s own stomach, such as fullness and discomfort.  Nausea, vomiting, belching, fast breathing, fatigue, irritability, drowsiness, and yawning are common symptoms. A delay in the emptying of stomach contents is thought to contribute to these symptoms. Feeling warm, with an increase in perspiration have also been described. 

The brain is constantly receiving cues to help with spatial orientation of the head. The main sensory inputs include vision, and input from the inner ear, or vestibular system, which senses linear, angular, and gravitational motion. Additional input is taken from the position in space of the rest of your body. If your body is actively moving, your brain can effectively estimate the position of your head. If there is no active movement, then your brain relies on your vestibular, visual and sensory systems. The theory behind motion sickness is that if these cues are incompatible, then the symptoms of motion sickness are generated.

Complications

There are several risk factors. Women are more susceptible than men. Pregnancy can exacerbate symptoms.  Severity tends to peak at age 12 and then decrease with age. Underlying diseases involving vision and balance tend to increase symptoms. Those with migraines can be at a higher risk.

Treatment

Modifying one’s environment is the simplest thing to do for prevention. Low frequency, lateral and vertical movements tend to elicit the most symptoms. So minimizing this sensation is the basis for environmental adjustments. We cannot control what our inner ear is sensing, but we can control what we are seeing. Having your vision fixed on the horizon or a fixed land mass, as opposed to the inside of a ship’s cabin may help. The theory is that matching up visual and vestibular cues decreases the symptoms of motion sickness. Positioning oneself on the most stable place in the vessel may also help. Being below deck and high up, are associated with worsening symptoms. Facing forward or in-line with the direction of greatest motion may help as well. Window seats or open-air locations are preferable. Body positioning is important. Minimizing head and neck twisting relative to body movement, and standing with flexed knees to anticipate movement can decrease symptoms. Lying down with eyes closed can also help alleviate symptoms. It is recommended to avoiding close work, reading, or watching a screen.

Eating bland, soft foods can help. Foods that induce an upset stomach/heart burn may exacerbate symptoms. Avoid alcohol, nicotine, noxious odors and maintain hydration. The psychological association of sea sickness has been well studied as well. Those who have anticipation of feeling ill are more likely to have symptoms.

Preventions

There are several medications that can be used to prevent and/or treat the symptoms. Some are over the counter, while others require a prescription. All treatments should be discussed with your doctor, to determine the safety of each modality, and which is best for you. 

Over the counter medications include antihistamines such as dimenhydrinate, diphenhydramine, chlorpheniramine, meclizine, cyclizine, cinnarizine. The newer generation of antihistamines that are considered non-sedating, are thought to be less effective. Common side effects of this class of medication are sedation, blurred vision, and dry mouth.  Less common but serious side effects, especially in the elderly, are confusion, and the inability to urinate.  These should be taken one hour prior to departure.

There are several prescription medications that may be used. Scopolamine, most commonly used as a patch applied to the skin every 72 hrs, has been proven to be effective in the prevention of motion sickness. It has not been proven to work for the treatment of symptoms. It is recommended to apply the patch 4 hours prior to departure. Side effects are similar to antihistamines. Scopolamine should not be used in people with certain types of glaucoma. Promethazine is a prescription drug that has shown to be effective in the prevention and treatment. Caffeine has been proven to be effective in conjunction with other medications.

Other natural treatment options have been proposed. Ginger, taking 1-2 grams, has been studies with a benefit in prevention of symptoms. Acupressure, in particular the P6 point, (3 fingerbreadths before the fold of the wrist, between the 2 prominent tendons), has been thought to help decrease symptoms. Manual pressure, or specialized wrist bands to apply pressure have been used.

Symptoms tend to decrease after repeated exposure to the movement, and tend to subside after 36-72 hours of exposure. Symptoms usually resolve within a few hours of the cessation of the movement. Once back on land, there is also a possibility of Disembarkation Syndrome. Many have described a feeling of disequilibrium, and the sensation of swaying, rocking, or walking on uneven ground. Nausea and vomiting are unusual. This may start within minutes, to hours after returning to solid ground.  These symptoms resolve usually within minutes to hours. Very rarely they can last a few days.

In summary, to prevent seasickness, it is recommended to optimize environmental factors, maintain hydration, avoid tobacco and alcohol, and use medical adjuncts after a discussion with your doctor as to which is best for you.

References:

1. Priesol, A, MD. Motion sickness. Uptodate.  Sept 2012
2. Brainard, A, MD. Motion sickness.  Medscape reference, May 2012.