Thailand Diving Tours boat and motion sickness
Scuba Diving Medicine Articles
Motion Sickness – Updated 2003
A ‘Hurl’ By Any Other Name Is Still As Unhappy
By Dan Kinkade, DAN Medical Information Specialist
Motion sickness – it goes by terms both descriptive and outlandish: mal de mer, seasickness, hurling, chumming for sharks, upchucking, tossing your cookies, blowing chunks. Divers know all about it; even if they haven’t experienced it firsthand, they’ve likely been witness to this form of involuntary fish feeding.
Sea sickness is not life-threatening, even though you might think – or wish – it were, when it’s happening. The good news: you are not alone. Ninety percent of all people will suffer from motion sickness at one time or another.
This article will explain motion sickness and offer ways to avoid or manage it while diving.
What is Motion Sickness?
Seasickness results when the eyes are seeing one thing – e.g., the inside of the boat – while the balance organ (the semicircular canals) detects another – your movement up and down. The brain gets confused, figuring out why your eyes tell it you are stationary, but your inner ear tells your brain you are moving.
Other factors can compound the problem: they include alcohol ingestion, anxiety, fatigue, odors (e.g., diesel fumes), being overheated and inner ear injury or infection. Signs and symptoms include sweating, nausea, headache, drowsiness, increased salivation and a sensation of spinning or dizziness. Vomiting may make you feel better, but the symptoms will not resolve until the inner ear acclimates to the motion or you use another form of treatment.
Seasickness tends to diminish after a few days without treatment. Generally, the more time you spend on a boat, the less severe the sickness becomes. When some individuals become acclimated to the motion, readjusting once they’re back on land may take some time.
How Can You Avoid Motion Sickness?
Positioning – If the boat is rocking bow to stern, seek out a spot in the middle of the boat for the least movement. A lower cabin may be more suitable than a top deck outer cabin. And remember, the smaller the boat, the larger your potential for sickness, as smaller boats tend to rock more quickly.
Fix on an object – Look beyond the boat: use the horizon as a reference point. This helps your brain to adjust more easily to the unstable environment. Avoid focusing tasks like reading, setting up equipment and writing.
Fresh air – If you’re feeling ill, nothing worsens it like diesel fumes. Find a spot away from the fumes, where fresh air blows. Keep a reference point by looking at the horizon.
Keep something in your stomach – Stay well hydrated before and during your trip. Sip water, juice or sports drinks, but avoid carbonated drinks, alcohol and caffeine. If you are nauseated, don’t drink lots of water since it will create an unpleasant sensation of sloshing in your stomach. Eat saltines or bread to absorb stomach fluids.
Some Remedies for Prevention
Plainly stated, there is no cure for motion sickness, but a plethora of medications, devices, procedures and herbal remedies are touted to alleviate its symptoms. If you have discovered a safe system that works, stick with it.
Over-the-Counter Medications
The classification of these medications is “antinausea.” The most common over-the-counter antiemetics are antihistamines: i.e. Bonine (meclizine), Dramamine Less-Drowsy (meclizine), Dramamine (dimenhydrinate), Marezine (cyclizine), and Benadryl (diphenhydramine). These medications work by affecting nerve pathways between the vomiting center in the brain and other control centers. These effects are associated with relief of nausea and vomiting.
Side effects of these medications may impair your ability to dive safely. Some cause drowsiness, the most common side effect. Because of this, they carry warnings about operating heavy equipment or performing hazardous tasks. Before using antinausea medications, always read the accompanying information. To evaluate for side effects, take your dosage well before the dive. If you feel drowsy while taking it on land, the effects may worsen underwater.
Medications by Prescription
Many divers have used Transderm Scop (the patch with scopolamine as its main ingredient) to relieve seasickness. With few reported problems, this patch releases the drug slowly through the skin; it can be very effective against motion sickness for as long as three days.
Since the medication affects the central nervous system, however, it can have side effects that may impair your ability to dive safely. The most common side effects are dry mouth and blurred vision. Fingers that contact the medication side of the patch and touch the eye will cause the pupil to dilate. After handling the patch, wash your hands thoroughly.
Other side effects, more common in children and the elderly include hallucinations, confusion, agitation or disorientation. The dosage is fixed and cannot be altered by cutting the patch.
You can get SCOPACE, a tablet form of scopolamine, by prescription. Taken an hour before travel, each dose will last up to eight hours. Benefits of the tablet over the patch can include a faster onset, flexibility with dosages and fewer side effects. For more information on Transderm Scop, see the upcoming November/December issue.
Other Forms of Prevention
Other non-drug remedies might help relieve symptoms of motion sickness.
Ginger, sometimes recommended for motion sickness, has been found to reduce electrical activity in the stomach, reducing contractions and thereby the nausea. A study conducted at University of Michigan in Ann Arbor proved ginger’s effectiveness in relieving motion sickness symptoms. Participants were spun in a large drum. When compared to those taking a placebo, those taking ginger had significantly less nausea.
According to the authors of the study, anti-motion sickness medications have significant side effects, such as dizziness and dry mouth. “Ginger appears to be an effective herbal alternative to the medications,” the authors concluded. Take 1 gram of ginger orally, followed by eating gingersnaps, drinking ginger ale or candied ginger.
The ReliefBand, made by Woodside Biomedical of Carlsbad, Calif., is advertised to relieve nausea and vomiting with gentle, noninvasive stimulation on the underside of the wrist. This battery-powered stimulator looks like a wristwatch; electrodes on the underside are positioned over the P6 acupuncture site. This is one inch toward the heart from the wrist, between the two-finger flexor tendons. When positioned properly, the wearer will feel a pulsed tingling sensation across the palm and in the middle two fingers.
The ReliefBand is the only device that has been cleared by the FDA for over the counter use for the treatment of nausea and vomiting due to motion sickness. It was also recently cleared for morning sickness. A similar device has been used as a prescriptive device for relief of post-operative nausea and vomiting.
The ReliefBand operates on the theory that the electrical impulse travels the median nerve and interrupts the nausea-related messages that are being transmitted between the brain and stomach. It can be used before or after symptoms begin. Although anecdotal, there have been reports of people receiving relief from the device even after being sick. The device is water-resistant but it’s not submersible, so divers should take off the device before entering the water. The band presents no side effects to interfere with a diver’s mental performance.
Another similar product is the Sea-Band, made in England and distributed worldwide. The Sea-Band is an elastic band with a button that applies pressure to the acupuncture site, much like the ReliefBand, but without electrical stimulation.
Motion Eaze, manufactured in Grand Rapids, Mich., is a concoction of natural oils that are applied topically behind the earlobe. These oils, which are absorbed, reportedly calm the inner ear, relieving the symptoms of motion sickness. It has no known side effects and, like all these remedies, its effectiveness can vary from person to person.
What Should You Do?
Before traveling, be adequately hydrated, nourished and rested. However, if you start to feel apprehensive about the boat ride or plane trip, don’t eat a large meal before departure. Munch on crackers and sip water or a sport drink.
Before you leave the dock or get into open water, set up your dive gear. This will keep you from looking down while moving through swells. Find a spot on the boat with the least amount of motion, good ventilation and visual references.
Believe in what you use, medication or non-medication; that means testing it for side effects before a trip. You don’t want to get out on a boat and find out you are too drowsy to dive – ruins a perfectly good dive trip. Dive safely.
About the Author
DAN Medical Information Specialist Dan Kinkade, NREMT-P, has been with DAN for two years, both full-time and as remote DAN medic. A paramedic for 25 years, Kinkade has been diving since 1974.
