Dr Ed Reeves outlines a variety of treatments intended to alleviate the misery of seasickness – while noting that prevention is better than cure, in this extract from Heavy Weather Sailing
This is an extract from the 7th edition of Heavy Weather Sailing, published by Bloomsbury.
Almost anyone who has put to sea will have encountered seasickness, either as a sufferer or a witness. Perhaps a well-planned sea passage with a strong crew became more arduous as the number of healthy crew members gradually reduced; or a day-sail with a non-sailing guest whose initial joie de vivre was overtaken by the quiet yawning and loss of colour that typically precedes the onset of nausea.
It is no surprise that the word ‘nausea’ itself derives from the Greek word nausia meaning ship-sickness, for seasickness dates back as long as man has travelled by water. The complex human balance organ (the vestibular system of the inner ear) evolved over billions of years to cope with humans as self-propelled animals. This balance system has not yet had the time to adapt further to the relatively recent arrival of other forms of propulsion such as boats, cars and space travel. Seasickness is the commonest form of motion sickness, a major nuisance to recreational sailors and even more so to occupational seafarers.
The role of the vestibular system in seasickness was first suspected in the late 1800s when it was noted that people suffering from deafness at an early age were largely immune to seasickness. Conversely, anyone with normal hearing is susceptible given the relevant conditions, to which end it is reported that nearly 100 per cent of liferaft occupants get seasick. The oft-heard claim that ‘I never get seasick’ might be more cautiously worded: ‘I have never yet been exposed to conditions that made me seasick.’
History reveals some surprising sufferers, not least Admiral Lord Nelson who, just a year before the Battle of Trafalgar, wrote: ‘I am ill every time it blows hard, and nothing but my enthusiastic love for the profession keeps me one hour at sea.’ Charles Darwin was troubled by recurrent bouts of seasickness on his voyage on HMS Beagle. Whilst they both achieved great feats despite their illness, the Duke of Medina Sidonia, who commanded the Spanish Armada in 1588, was plagued by sickness which in all likelihood hampered his ability to lead effectively.
Of course there is wide variation in susceptibility to seasickness, some of which is predictable and some not. In practice, around one-third of people
will suffer to a sufficient degree that they like to take precautions prior to sailing, and most of them (but not all) will ‘get their sea-legs’ after a few days. Young children under the age of two years are immune, while from the age of two to 12 years children are the most likely to feel sick. Women, especially during pregnancy and menstruation, are more prone than men to become ill during a voyage, and Asian races are also more at risk of seasickness than non-Asian races. If you are thinking of taking a pet on a cruise, remember that animals share a very similar vestibular system and are also vulnerable to seasickness.
Cause and treatments
There has been much research into the cause of and treatments for seasickness, leading to a range of ways to try to ameliorate its effects. The mere fact that a range of strategies is required probably gives the clue that no single cure has been found. However, to have the best chance of warding off seasickness it makes sense to develop an understanding of how and why it occurs.
Nausea and vomiting serve a protective purpose for humans – by removing unwanted contents from the stomach. This mechanism provides a defence against the ingestion of poisons, or foods that have gone off. In other words, nausea and vomiting are normal and important physiological processes. The control centre for the process of vomiting is an area in the brainstem known as the vomiting centre.
The vomiting centre can be triggered by a wide variety of different stimuli. For example, when a poison is detected in the bloodstream or the gut, messages are sent to the vomiting centre, which then activates the vomiting response. These messages are transferred to the vomiting centre by the release of ‘neurotransmitters’ such as histamine or acetylcholine. The vomiting centre can also be triggered by other stimuli such as pain, fear, smells and, most importantly for our purposes, by the imbalance associated with motion sickness.
Balance is achieved by the brain interpreting information from three main sources – eyes, muscles and joints – and the vestibular organs in the inner ear. When there is a mismatch between the information that the brain is receiving from these sources it results in a feeling of imbalance. This is sometimes referred to as the ‘sensory conflict theory’. So for example, sitting in the cockpit, feeling cold and wet and perhaps slightly anxious, the vomiting centre is primed. All it now takes is messages from the eyes (staring at the cockpit floor) to conflict with messages from the vestibular organ in the ears (which are detecting the three-dimensional rolling and pitching of the yacht) and the vomiting centre is triggered. The result is inevitable.
Prevention is better than cure
Thorough preparation goes a long way to preventing seasickness. The first aim is to reduce the factors that lower the threshold for seasickness, including tiredness; dehydration; getting cold and wet; fear and anxiety; smells; lack of mental stimulation; reading from screens, charts or almanacs.
It pays to be well rested and nourished prior to and during a voyage (remembering here the role of establishing a watch system to ensure everyone aboard remains rested). While alcohol and food excess are best avoided, a light meal of mixed carbohydrates and protein may reduce the tendency to seasickness. Eating and drinking small amounts frequently is a helpful strategy, so it is a good idea to have readily-available snacks and water bottles. For snacks, saltines (the author’s favoured choice being Ritz biscuits) and ginger (of which more later) both have their supporters. Hot meals are important for crew morale and nourishment, but planning for easy meals avoids prolonged time in the galley and smells that can be nauseating to those struggling with seasickness.
An essential part of preparation is choosing appropriate clothing. Being warm and dry increases resistance to the effects of seasickness and avoids the need to change from cold and wet clothing if nausea should develop. The three common enemies of a safe and happy passage, namely cold, fatigue and seasickness, will each make the other two worse. Cold and fatigue will exacerbate the nausea.
Fear and anxiety affect seasickness, which perhaps explains why the inexperienced are afflicted more than old salts. Apprehension dulled by alcohol is a bad combination. If novice sailors have confidence in the skipper and are given a specific simple task as their own, then much misery can be alleviated.
Time spent focused on reading, navigating or staring at electronic screens risks aggravating seasickness. The eyes will be sending a message to the brain of a relative lack of movement, while the vestibular organ will be detecting movement. Good preparatory passage planning enables this to be minimised for seasick-prone navigators. By contrast, closing one’s eyes removes one of the confusing signals and can help prevent the onset of nausea.
Keeping the mind active distracts the higher centres of the brain from the sensory mismatch that lies at the root of seasickness. Skippers, who carry the ultimate responsibility for the boat, are often less seasick than the crew. Conversation, singing, word games, ‘I spy’, all have good anecdotal track records. The classic prevention strategy is to take the helm. This combines having a sense of control with the need to concentrate and to look at the horizon, and can have a dramatic effect on preventing or relieving seasickness. When looking at the horizon, the messages from eyes and vestibular organs are less in conflict, so this in itself can be an effective strategy.
‘Getting your sea-legs’ is an expression that describes a process called habituation or adaptation. Repeated and increasing exposure to the motion of a boat provides the opportunity for the brain to adapt its response to sensory conflict. Unfortunately, ‘sea-legs’ are quickly lost again if exposure to boat motion ceases (medical justification for the viewpoint that more sailing is good for your health?).
There are of course multiple reasons for early reduction in sail area as wind increases, not least of which is the improvement of a yacht’s motion and the resulting beneficial effect on seasickness. Another technique, to reduce the amount of movement that the confused brain is struggling to interpret, is to seek the spot on the boat with least motion, ie near the keel. Lying supine (face upwards) on the cabin floor above the keel, with eyes closed, has much going for it.
Ginger has a good reputation for the alleviation of nausea. There is evidence of its effectiveness, such as a trial involving 80 Danish naval cadets who were given either 1gm of ginger or a placebo: the cadets given ginger suffered significantly less vomiting and sweating than the placebo group. Another study found ginger to be more effective at reducing motion sickness than the drug diphenhydramine when participants were put in a rotating chair.
To paint a fuller picture, it must also be mentioned that some other studies have been less conclusive about the benefits of ginger. However, ginger is readily available and can be easily consumed. Choosing a dose is imprecise, but around half a gram of dried ginger seems to be the consensus, taken about half an hour before setting sail. In practical terms, quarter to half a teaspoon of dried ginger mixed with a cup of hot or cold water makes a good drink, or better still use about 1in of peeled and chopped fresh ginger root. Ginger capsules, candied ginger, ginger biscuits (five or six of them) or ginger ale are other easy forms of ginger that can be kept in the yacht’s stores.
Another popular non-drug treatment is applying pressure at the Nei Guan (P6) acupressure point. This is located three fingerbreadths above the wrist (on the same side as the palm of the hand) between the two prominent tendons. Most chemists sell a product called ‘Sea-Band’ which comprises a pair of elastic wristbands with plastic studs that apply pressure at the correct point. While clear evidence of their effectiveness in reducing motion sickness is lacking, they certainly have many supporters who swear by them, and studies have demonstrated a reduction in nausea and vomiting in post-operative and chemotherapy patients with the use of acupuncture.
Electronic wristbands purport to work by a similar mechanism by sending a variable electric current into the wrist at the Nei Guan acupoint.
A visit to the pharmacy for motion sickness pills can be a confusing experience. Confronted by an array of options it is all too easy to go for the best branding, rather than making an educated decision on what to buy. Forearmed with a little knowledge, a somewhat more rational choice can be made. The drugs Phenergan, Avomine, Sominex and promethazine, for example, are all the same; but be warned, in the US Sominex is the market name for a different drug, diphenhydramine (which in the UK is sold as Nytol). Confused?
Rule one in choosing drug treatments is therefore to look for the name of the active ingredient rather than the trade name. It is much more effective to prevent seasickness by taking medication in advance of travelling, than to wait for the symptoms to start and then try to treat seasickness. To this end, one should carefully read the instructions to see how long prior to a voyage the medication should be taken, as this ranges from 20 minutes before travelling (eg hyoscine) to the night before (eg promethazine). The commonest error when taking drugs for seasickness is to take them too late.
Many of the drugs used for seasickness also have a place in the market as over-the-counter sleeping pills. While this might be useful for children on a long passage, it is certainly not a great deal of help for the night watch-keeper. In fact, the choice of drug treatment is a delicate balance between effectiveness at preventing nausea and sickness versus side effects. Other common side effects include dry mouth and blurred vision, and in rare circumstances hallucinations and confusion.
In order to make some logical decisions about which medication to use, it is useful to divide the available drugs into two groups according to how they work (which of the previously mentioned ‘neurotransmitters’ they predominantly block). Hyoscine (sold in the UK as Kwells and Joy-rides) sits in a group on
its own, being an anticholinergic (anti-acetylcholine) drug. It is probably the most effective drug available and works quickly, but its use tends to be limited by side effects. It does come in a popular patch preparation, called Scopoderm, which is available on prescription. The patch is placed on the skin behind the
ear and slowly releases hysocine into the bloodstream through the skin, thereby minimising the side effects. Each patch lasts for 72 hours. Care needs to be
taken to wash your hands carefully after handling the patch, as inadvertently getting hyoscine in your eyes will cause pupil dilation and inability to focus
All the other commonly-used drugs belong to a group of old-style (first generation) anti-histamine medications. These differ from the newer (second
and third generation) anti-histamine medications, which are commonly used for hay fever and allergies, in that they can cross the blood-brain barrier and hence gain access to the vomiting centre. How people respond to different anti-histamines is somewhat unpredictable, but loosely speaking, as they get stronger they cause more drowsiness. The standard mid-strength anti-histamine is cinnarizine (Stugeron), which for many people offers an effective balance between reducing
the symptoms of seasickness and dealing with unwanted side effects. At the strongest end of the scale is promethazine, which is useful for sufferers who don’t mind sleeping through it all. It is of note that MCA Merchant Shipping Notice 1768, which sets out the regulations for medical stores on coded vessels, lists cinnarizine and hyoscine as the required tablets for motion sickness, and a promethazine injection as the treatment for severe motion sickness.
One way of counteracting the drowsiness that many remedies cause is to take pseudoephedrine (available over the counter as Sudafed) in a dose of 15-30mg every 4-6 hours, in combination with, for example, promethazine.
Due to the variable effects that drugs for motion sickness can have on different people it is sensible to ‘test drive’ your planned remedy on dry land prior to using it in earnest in rough seas. It should be remembered that these are potentially powerful drugs, and you should consult the pharmacist particularly if you have other medical problems such as glaucoma, high blood pressure, heart disease, epilepsy or prostate trouble.
Managing a seasick crew
It is usually quite clear to all on board when a crew member is falling foul of seasickness. There is the uncharacteristic quietness, rapidly followed by skin
pallor or even the dreaded ‘green tinge’. Questioning might elicit a degree of dismissive bravado. At this stage, the situation may be redeemable by putting into action some of the strategies covered so far, but perhaps the most important is to remember the safety aspect. Judgement can often by impaired and the body weakened by seasickness – a lurch to the leeward rail to vomit can become risky, so ensuring that the victim is wearing a harness and clipped on is particularly important.
At this stage, involving the crew member in some form of activity helps to provide welcome distraction for the brain. Helming seems to work particularly
well, probably due to the combination of looking at the horizon and concentration on the motion of the boat. A similar effect is seen in cars: how often do you hear of a car driver feeling travel-sick? When not on deck the sufferer should be helped to find a good berth in which to rest, away from the pitching movement of the bow or stern so as near amidships as possible. They should be encouraged, or helped, to get out of cold wet clothes and into a warm sleeping bag. Lying with eyes closed to reduce the conflicting visual messages, and wedged into a snug bunk (lee cloths and bags or cushions to help reduce them from rolling around) is the optimal position. Strictly no reading, as this will surely aggravate their symptoms. A bucket should be provided in case of vomiting, and regularly emptied to avoid others having to deal with a cabin smelling of vomit, which is certain to tip other vulnerable crew over the edge.
In terms of medication, anything that requires swallowing will probably no longer work. The fastest-acting drug is hyoscine (Kwells) and it works best to chew the tablet and then let the chewed tablet sit under your tongue or against the inside of your cheek. This allows it to get absorbed through the lining of your mouth, bypassing the stomach. The same can be tried with cinnarizine (Stugeron), although it may take longer to work. Scopoderm patches also get absorbed directly into the bloodstream, but again take a few hours to work.
For many, these simple actions will allow the nausea to subside. For some, a quick vomit will provide a good period of relief. For a significant minority, however, the misery of seasickness is profound. The saying that ‘at first you fear that you might die, and then you fear that you might not’ captures how unpleasant the sensation can be. Sufferers at this more severe end of the spectrum become a danger to themselves, and need firm direction to avoid falling into a state
of hypothermia and dehydration. It is particularly important to ensure that they have adequate water to replace that lost through vomiting.
Oral rehydration solutions
Better still than water are oral rehydration solutions (such as Dioralyte) which are readily available in all chemists. These balanced solutions provide an isotonic fluid that is easily absorbed by the stomach and replaces essential lost chemicals (particularly sodium) as well as fluid. They come in the form of tablets or sachets to mix with a specified volume of water. Taking small amounts regularly tends to work best. Since the adoption of the widespread use of oral rehydration therapy (ORT) in the 1980s, many millions of lives have been saved from diarrhœal illnesses such as cholera, particularly in developing countries. ORT forms one of the mainstays of treatment for gastroenteritis in any setting, and on a yacht is invaluable at preventing a crew member with seasickness from becoming weak and dehydrated.
Fortunately, making landfall usually leads to rapid and full recovery. A very small minority of unlucky people will develop ‘mal de débarquement’ or ‘disembarkation sickness’, in which a persistent sensation of motion is felt even once ashore.
Dr Ed Reeves qualified at St Thomas’s and joined the Chawton House Surgery, Lymington in 1999. He has a particular interest in minor surgery, and as a keen sailor he is also the medical officer for the local RNLI.
Extracted from Heavy Weather Sailing
7th edition, Peter Bruce