Dear Doctor Column, June 16, 2008

Riding the Waves—Preventive Measures for Motion Sickness

Question:

I'm going deep-sea fishing next month. How do I prevent motion sickness? I feel queasy just thinking about it, but I really want to go. Any advice?

Answer:

Perhaps the only thing worse than being seasick is having to help hold the head of someone else turning green. Once symptoms begin, there's not a lot you can do for relief apart from getting to solid ground, so you're wise to seek help before going on your outing.

Motion sickness, which includes carsickness, seasickness, and airsickness, occurs when the brain receives confusing data from body sensors telling us where we are in space. These sensors include eyesight, nerve receptors in joints and muscles, and the balance mechanism in the inner ear that sends messages to the brain regarding balance and movement.

Normally, the brain sorts messages from these sensing organs keeping us stable and feeling well. When information from one sensor differs from information received from another, however, the brain has problems unscrambling the messages and sends out distress signals causing dizziness, nausea, vomiting, and cold sweats.

For example, if you're inside a large ship and can't see out, ear and joint sensors detect the boat's pitching and rolling, but your eyes don't see any movement. Similarly, when an airplane is banking a turn for a landing while you're reading, your body senses the turn, but your eyes focused on the page don't perceive it.

No one knows why some people are more susceptible to motion sickness than others. Children aged 2 to 12 years are most susceptible, whereas infants rarely suffer from this problem. The good news is susceptibility gradually decreases with age; motion sickness is uncommon after people reach 50 years.

Motion sickness can spoil a trip or excursion but these preventive measures may help you avoid the problem:

• Place yourself where there is the least motion. In a car, sit in the front seat looking straight ahead; on an airplane, choose a seat over the wing; and on a boat, stay near the middle, on deck rather than below deck.
• Lie in a semi-reclined position and keep your head as still as possible.
• Focus on the horizon. If no horizon is visible (on an airplane, for instance), close your eyes and try to doze.
• Do not read while traveling.
• Avoid watching or talking to someone near you who's experiencing motion sickness.
• Skip alcohol. Instead, sip water or a noncarbonated beverage.

Some over-the-counter antihistamines, such as Bonine, Marezine, Dramamine, and Benadryl, have been approved by the Food and Drug Administration for motion sickness. Be sure to take them 30 to 60 minutes before you leave, following the directions on the package. Be aware that these medications can cause drowsiness and you shouldn't drive after taking them. Ginger root has long been used to ward off the nausea motion sickness, despite a lack of scientific data to back up this claim.

If these simple remedies don't help, ask your doctor for a prescription. The cholinergic blocker scopolamine, (sold under the name Transderm Scop) or the oral formulation (Scopace), can decrease symptoms. Administered through a skin patch, Transderm Scop is applied behind the ear 6 to 8 hours before traveling and is changed every 3 days. Transdermal scopolamine, which starts to work about 4 hours after it's applied, is appropriate for longer voyages and reduces symptoms during all common modes of travel. 

The transdermal formulation tends to produce fewer side effects than the oral form, which is effective for 6 to 8 hours and can be used for short journeys or for bridging the time between application of the patch and the onset of its effectiveness. The oral 8-hour tablet is taken 1 hour before traveling. The most common side effects of both the oral and transdermal formulations are dry mouth and eyes. The patch should not be used by individuals with heart disease, nor are they recommended for children.

Over-the-counter drugs, such as dimenhydrinate (Dramamine, and others) or meclizine (Bonine, and others), are less effective, but may be helpful for milder symptoms.

Another prescription drug is promethazine (Phenergan, and others), which is taken once a day, starting before bedtime the night before travel. As with antihistamines, promethazine may be sedating, but is probably the most potent medication used for motion sickness.

To read more about motion sickness and specifics about various medications, visit the Centers for Disease Control and Prevention page on the topic.