There's an English sailors' proverb that states, "The only cure for seasickness is to sit on the shady side of an old brick church in the country." Speaking for those of us who have suffered from the affliction, I might be a bit less poetic. We'd be happy to sit in the shade of anything that wasn't moving.
The history of seasickness is as long as the history of going to sea. The first medical accounts appear in the writings of Hippocrates. Two thousand years ago, while traveling back and forth to the Aegean island of Kos, he must have had the opportunity to observe seasickness in his fellow Greeks (and most likely himself) often enough.
"Sailing on the sea proves that motion disturbs the body," was the father of medicine's terse appraisal. It took two millennia more to uncover the true causes of seasickness. The first real clue came in the 1880s when someone observed that most deaf mutes didn't get seasick. This suggested that the malady had something to do with the inner ear.
Up until then it had been assumed that the stomach was the suspect organ and that seasickness was caused by its 'shifting' around with the intestines. In the 19th Century, sinister looking devices resembling corsets with horse cinches could be worn about a person's middle to restrict this shifting. Some purveyors even went so far as to recommend that these medieval girdles should be wired to batteries so that an electric shock, like a cattle prod, could be given at the first signs of queasiness.
Without going into nauseating detail (by the way, our word nausea comes from the ancient Greek naus meaning ship), most current evidence suggests the cause of seasickness is due to a conflict of sensory information from three main sources: vestibular (balance) sensors in the inner ear, visual sensors and position sensors.
Each of us has unconsciously learned to keep our balance by integrating information from these three sources. But that learning has taken place on good old terra firma. The moment we swing our sea bag over the lifelines and step off land, we're at a disadvantage. Once the lines are cast off and the sails start to draw, our sensory input becomes confusing: our eyes see the horizon tilt, our legs sway back and forth to keep it horizontal, and the balance sensors in our inner ear are reporting that, actually, we're going up and down.
Many people can still maintain their composure as the brain tries to sort out these reports from the precincts. But now suppose that you're getting cold so you go below to find your jacket. Suddenly, the whole world changes. Your legs and inner ear are still rockin and rollin' away, but your eyes see a berth that appears as stable as your living room. In fact, everything below looks level and secure, but your other senses tell you it's far from it. Immediate sensory conflict. The situation is aggravated if there are any unpleasant odors below: gas/diesel fumes, a fouled head, dirty bilges, spoiled food or someone else vomiting.
If you are still reading this and wondering what the hubbub is all about, you may be one of the few fortunate souls who think you do not get seasick. Despite appearances, it's been shown that almost no one is completely immune. If conditions get rough enough, almost everyone will get seasick. That said, only about a third of us have enough of a problem to require some preparation before we go to sea.
A report on the incidence of seasickness in the 1992-93 British Steel Challenge in the September, 1995, issue of Aviation, Space, and Environmental Medicine confirmed what many long-distance sailors already know: The critical factor on extended sea voyages is the time spent at sea. At the beginning of each leg of this upwind round-the-world race, approximately a third of the crew felt ill and one out of five vomited. By the end of two days there was a rapid decrease in illness, and although there was wide variation in the rate of habituation, by the 10th day less than 5% of the crew were reporting seasickness.
This study also confirms something we all know intuitively - the frequency of sickness is greatest when sailing into headwinds and least when the wind is abaft of the beam. Unfortunately, it also confirms that even though you may have been at sea a few days and think you've got your sea legs, if there's a course change bringing you into headwinds, the incidence of sickness doubles. A very interesting finding was that people can often judge their susceptibility to seasickness. Simply pay attention to how much of a balance problem you have upon return to land. If you're really wobbly for more than a few hours after docking (mal de terre really), you run a greater risk of seasickness.
While we're on the subject of susceptibility, consider the following. Less likely to get seasick: Children under the age of 5, adults over 50, males (only in the reported sense of 'illness'; men and women have the same incidence of vomiting), and anyone of non-Asian ethnicity (a report in the 1996 Journal of Human Heredity noted Asians were more prone to seasickness than other races).
What about physical conditioning? The general perception is that being overweight and/or out of condition can make one more susceptible to seasickness. This may trace its roots back to a hoary old volume, the 1895 edition of The Shipmaster's Medical and Surgical Help and First Aid, which states, "In some persons...especially weak lads, the attack often lasts longer and is very severe for many days…"
In 1990, some Canadians decided to look into this concept. They took a group of 'unfit’ subjects and tested their susceptibility to motion sickness before and after an endurance training program. In essence, they said, let's shape up this bunch of soft guys and see if that’ll keep them from puking. Testing consisted of strapping the 'doughboys' into a particularly evil device euphemistically named the Precision Angular Mover which tumbled them head over heels at about 20 times a minute in total darkness and waiting for them to vomit.
Following this, the subjects then spent several weeks in a rigorous training program, which resulted in significantly improved physical strength and endurance, and a marked decrease in body fat. These guys had now become fit. Then they were tossed back into the machine. And guess what? They were found to be more susceptible to motion sickness than before! While this may be the only study in the annals of modern medicine to suggest fitness isn't the answer to everything, it doesn't mean sailors should not strive to be fit. It also doesn't mean fat people don't puke.
What about a psychological component to seasickness? We've all heard about or perhaps know individuals who become sick merely seeing a boat. Is this for real? Yes, it is. Should such an individual go to a seasickness therapist? Maybe. In 1994, the Naval Biodynamics Laboratory reviewed experimental work that suggests cognitive-behavioral techniques - desensitization programs - can be successful in reducing the psychological component of seasickness.
Okay, now that you now know more about who gets sick and some of the factors causing seasickness, what about prevention and therapy? Here are some basic tenets for avoiding mal de mer:
- Avoid excessive food or drink prior to sailing. Stomach distention from too much dinner definitely makes you more prone to nausea.
- Avoid booze. Alcohol is a vestibular (balance) toxin. The same factors that make you sick a thousand miles from any ocean will increase your chances of getting seasick manyfold.
- Once at sea, stay above decks if you can, preferably somewhere amidships where the motion is most easy. It also helps to keep busy - volunteer to steer, handle lines, trim sails, whatever.
- Study the horizon. By keeping your attention focused on distant objects there is less 'neural conflict.'
- Finally, know your susceptibility and take the medicine or use the remedy that has worked for you in the past. And do it early, before you start to get sick.
But, you ask, what if I don't know what works for me?
If you don't know, but you want to find out, start with the simplest method that has the fewest possible side effects. If that doesn't work, go to the next level.
A good place to start is with Sea Bands®, those small sweat bands which, by means of a little built-in knob, apply acupressure to certain points on your wrist. Simple, inexpensive, and for many people, effective. Effective? Actually, yes. Well, maybe yes.
There is certainly controversy in the medical literature and many papers have been published arguing both sides of the question. In one of the more recent studies, researchers in the Department of Psychology at Humboldt State University reported that for some types of motion sickness (in their study, visually induced by rotating a striped drum in front of the subjects eyes), acupressure at the P6 point (middle of wrist) significantly reduced the incidence and severity of symptoms.
Unfortunately, that study only tested acupressure itself, not the wristband specifically. Other studies have questioned the effectiveness of the band. For example, a 1990 study at the Institute of Naval Medicine in England demonstrated the band had no anti-nausea effect in motion-induced sickness. But their subjects had to endure a machine similar to the Precision Angular Mover, which could make a rock throw up.
Scientific studies notwithstanding, there is certainly plenty of anecdotal evidence that wristbands work for some people. Marc Kraft, who runs Pacific Yachting and Sailing School in Santa Cruz, swears by them. He offers Sea Bands® as a first line of defense to all novice sailors who are unsure of their seasick susceptibility. However, it should be noted that he is very upbeat about the product and absolutely assures them it will work. The good old placebo effect?
As long as we're on the subject of 'alternative' approaches to seasickness, consider Alpha MS, a combination homeopathic preparation available in some health/natural food stores. Like most homeopathic preparations, it comes in pellets which are dissolved under the tongue. There are no side effects, but I know of no well-crafted studies proving the value of the preparation. Still, there are many anecdotal accounts of its success.
A familiar old standby is ginger. Believe it or not, studies have shown it to be effective. It can be taken as a tea or in one of the commercially available bottled ginger drinks. Again, no side effects. There are many other remedies touted to work, but I advise you to check out their real benefits before wasting your time, money, or your lunch.
If all else fails, the final line of defense is medication. There are basically three categories of drugs which have anti-seasickness effects. The first and most familiar group are the antihistamines: dimenhydrinate (Dramamine®), meclizine (Bonine®, Antivert®), cyclizine (Marezine®), and promethazine (Phenergan®). Actually, promethazine is in another group of drugs called phenothiazines, but it has powerful anti-histamine properties.
The second group, anti-cholinergics, includes the well-known drug scopolamine (the active ingredient in the TransdermScop® patch). The third group includes what are called sympathornimetics such as dextroamphetamine (Dexedrine®) and ephedrine. Let’s talk a little about each of these groups.
antihistamines are mostly sold over the counter, without a prescription. For many, these drugs work fine, but side effects are common. The most bothersome is drowsiness. Last year, before our annual training cruise aboard the USTS Golden Bear (the California Maritime Academy's training ship), I offered cadets and crew Marezine®. That's our standard preventive medication and we are quite familiar with its effects. Those who chose to take it started about 12 hours before our intended departure time.
However, at the last minute, we had to delay our departure by 24 hours. We advised that everyone who had started taking the medication simply to continue with it until we left. By the time we finally did leave, many had been taking the Marezine® for over 36 hours. And a most interesting observation was made. The medication worked as expected; but far fewer people reported side effects.
Did the 36 hours give time for some sort of habituation process to occur? I don't know for sure, but certainly there was less drowsiness, Iess dry mouth, less blurred vision. So, for those of you who are troubled by the side effects of antihistamines, try starting the medication earlier.
I am often asked about the subgroup of antihistamines that don't list sleepiness as a side effect asternizole (Hismanol®) and terfenadine (Seldane®). It's true, they don't make you drowsy. Unfortunately, studies have shown that they don't do anything to prevent seasickness, either.
What about safety during pregnancy? Dimenhydrinate, meclizine, and cyclizine are all Risk Category B drugs, which are considered safe. Promethazine has a C rating despite a preponderance of evidence to support its safety. So pregnant women should consider its use only when other treatment has failed.
The anti-cholinergics (scopolamine) are generally more effective than the antihistamines but they also have more side effects. The most popular prescription has been the scopolamine patch (TransdermScop®). But at present its effectiveness is moot - it's no longer on the market. It has been unavailable due to problems with production, and the problems were significant enough to require reapproval from the FDA. Hopefully, that's not as bad as it sounds. CIBAGiegy has told me that they intend to bring it back sometime later this year. You can still get scopolamine in pill form, but by prescription only.
In either case, patch or pill, remember scopolamine has considerable side effects and can produce any or all of the following: dryness of the mouth, blurred vision, disorientation, confusion, difficulty urinating and sudden onset of narrow angle glaucoma (pain and reddening of the eyes accompanied by dilated pupils). It is a Risk Category C drug for pregnant women and not recommended. Children are especially prone to the side effects and shouldn't take it, either. In older men, particularly those with urinary problems, that 'difficulty urinating' can translate to urinary retention that sometimes requires emergency catheterization. Not a very pleasant thought.
About the only time I prescribe scopolamine now is for professional sailors or fishermen who are prone to severe seasickness but must go to sea because their livelihood depends on it. And in most cases, that's only after all other methods have failed.
It's worth noting that the most effective anti-seasickness treatments are scopolamine combined with one of the drugs in the sympathomimetic group (Dexedrine® or ephedrine). Multiple studies have shown that the best regimen is 0.6 mg of scopolamine plus 10 mg of Dexedrine®. This combination seems to combine the best attributes of each drug's anti-seasickness properties, while at the same time 'canceling out' many of the side effects of each, but I reserve this for only the hardcore cases. A safer combination is promethazine (2550 mg) plus ephedrine (2550 mg).
What to do when all has failed and there you are - puking, feeling miserable, unable to eat or drink, and worried that you might soon become dehydrated? About the only thing left at that point is promethazine via injection or rectal suppository - 50 mg should usually do it, maybe repeating every few hours as needed.
If that's not an option, the only advice can offer is to rest in the most stable part of the boat, pad your head to minimize movement, and sip small amounts of water. And wait. You may not feel like you want to live, but you will.
- kent benedict, md
This story was reprinted from the the May 1997 issue of Latitude
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