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Medical Information

When you want, or need, to know more than the superficial, such as when you are

where there is no access to a physician.

Prototypically: Medicine at Sea


This medical information is provided for education purposes only. I am making no attempt to practice medicine over the internet. This is being written to give some basic knowledge for those that are physically isolated from access to professional medical care, such as sailors at sea. This is to help in deciding whether an emergent medical condition exists, how to initially deal with it, and whether evacuation is needed. It is by no means exhaustive or meant to replace personal medical attention. Please do not contact me regarding your personal condition. Over the years I have received many emails from people asking for help with their personal chest pain, or whatever. Sometimes they write during acute pain. This is ridiculous. You can't practice medicine over the internet. If I find their email, after it has been filtered by my spam filter, it may be days or weeks later. My response, if any, will be to contact their regular provider. Even a bad doctor in person is better than an email. Please use this information in the spirit in which it is intended.

Sincerely, Mark R. Anderson, M.D.

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Mal de Mer

Sea Sickness Prevention and Treatment

© Mark R. Anderson, M.D. 2000


v.1.3 10/31/09


Here are my personal but hopefully flexible seasickness recommendations.

Above all use what has been helpful in the past whether it is meds, wrist bands, meditation, ginger or whatever. There is a great deal of variance in whether people like to start a voyage on an empty or full stomach. Generally you should avoid alcohol and heavy fatty meals before the voyage. Practically everyone develops a resistance to motion sickness within three days so the preventative medications are generally only needed for the first 1-3 days of a voyage.

1st line: Preventation:


The patches that last for three days are again available. Do not cut them since rupturing the blister of medication will lead to irregular absorbtion with increased chance of toxicity. If the patches aren't available, there are some compounding pharmacies that can make a scopolamine gel that is placed on the skin under a plastic cover. The gel only lasts 6-8 hrs.. Scopolamine tablets are available by prescription under the name Scopace. More info is available at

Various antihistamines:

1st choice due to less side effects: Meclizine, 12.5 to 25 mg. every 24 hrs. Up to 25 mg.every 6 hrs.. This is available over the counter (OTC) as Bonine® and Dramamine II®. The prescriptive form is Antivert®. Oddly, the half strength (12.5 mg.) form is only available by prescription. The cheapest way to buy it is to just ask the pharmacist for a bottle of 100 tabs. No prescription needed.

2nd choice: Dimenhydrinate (Dramamine®) or diphenhydramine (Benadryl®) 25 - 50 mg. every 4-6 hrs. BTW, dimenhydrinate turns into diphenhydramine under the influence of stomach acid, so to carry both would be unnecessary. Likely to cause drowsiness.

3rd choice: (only because it's not available in the US and I've no experience with it) - cinnarizine (Sturgeron® and others). This has an excellent reputation by those who have used it.

Add pseudoephedrine (Sudafed® and others), 15-30 mg. every 4-6 hrs. if drowsiness is a problem. This should be avoided with a history of high blood pressure, heart irregularities and in combination with certain other drugs, esp. MAO inhibitor type antidepressants. In many places now you have to ask the pharmacist directly and sign for it, but no prescription is needed. This is to control it somewhat to reduce availability to those that cook methamphetamine from it. The other OTC Sudafed PE contains phenylephrine which may be no better than placebo. Ephedrine (Primatene tablets) has been used in the past. I'm not sure if it's any better.

Stay on deck and watch the horizon.

2nd line:


The above antihistamines if they are able to be retained, i.e. not thrown up.

Take the helm and watch the horizon, or lay on the cabin sole in mid boat w/ eyes closed.

Sips of clear non-carbonated beverages. Perhaps ginger tea. A way of getting ginger into you even if you're vomiting is to just hold a slice of fresh ginger root within your mouth between your teeth and cheek.

3rd line:

Desparate measures:

Promethazine (Phenergan®) - 25 mg. suppository every 4 hrs. as needed and lie down. Up to 50 mg. suppos. every 3 hrs. Promethazine pills are also available, as are shots but I basically don't recommend this drug unless you're already not able to take pills, and few people will want to carry injectable meds.

I don't recommend promethazine for prevention unless you know that the others don't work. Be especially cautious of sedation. The other antihistamine side effects may also occur. (See below.) There's an additional rather rare side effect of promethazine, (and other phenothiazine type drugs) that is called a dystonic reaction. In the most severe case you get an oculogyric crisis. Mild symptoms would be restlessness and difficulty controlling your eyes and or tongue. The full blown crisis finds the victim with the whole body in spasm with the neck and back arched, the tongue protruding, eyes rolled back, and barely able to speak. It's frightening but fortunately not directly dangerous. It can also be cured within seconds if given IV 50 mg. diphenhydramine, wihin 5-15 min. if the drug is given IM and 30-90 min. if given orally. It can recur over a few days so the diphenhydramine may need to be repeated every 4-6 hrs

Promethazine has some effect on lowering the seizure threshold of someone w/ epilepsy so this caution should be added, but it's often more a theoretical than a practical limitation.

4th line:

(assuming IV's aren't available) - Go ashore and sit under a tree.

The primary risk of severe sea sickness is dehydration and electrolyte imbalances. This can generally be prevented and treated by taking frequent sips of a clear liquid diet. This should consist of a variety of fluids such as flat 7-Up®, ginger ale, apple juice, Gator-Ade®, etc.. Using a variety of fluids counteracts the problem that none of them are ideal by themselves. Pedialyte solution is excellent by itself, if you happen to have it. A pretty well balanced solution similar to the World Health Organization's oral rehydration solution can be mixed up with common ingredients.

Oral Rehydration Solution: Please see the rehydration formula and instructions in my Cruising Medical Kit.

Antihistamine problems:

Contraindications and cautions: High blood pressure, glaucoma, prostatic enlargement.

Side-effects: Drowsiness, dry mouth, goose bumps, blurred vision, chills, urinary retention, hallucinations: roughly in order of decreasing frequency. There are prescription antihistamines with a much lower likelihood of drowsiness, but they are also less reliable in their effectiveness for allergic reactions so I presume they'd be less reliable for motion sickness. Your own experience with these medications, (e.g. Zyrtec, Claritin, Allegra, Hismanal) should guide your use. Please be aware that some of these newer medications can have life-threatening reactions when combined with certain antibiotics (e.g. erythromycin) and antifungals (e.g. ketoconazole), or if taken in excessive doses.

Mark Anderson, M.D.



Cruising Medical Kit

Other Medical Information

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