Seasickness: why it happens and how to stop it

Why ships make your stomach revolt

Boats and ships don't move like cars. The motion is rolling, pitching, and slow, sometimes all at once. Your inner ear feels every degree of sway. Your eyes, locked on a stable-looking cabin wall or ceiling, see almost nothing happening. Your brain decides the disagreement is suspicious and pulls the nausea lever.

Big modern cruise ships hide the motion well most of the time: hydraulic stabilizers reduce roll significantly. But in rough seas, no ship is fully immune, and on smaller vessels every passenger feels every swell. In a survey of 20,029 ferry passengers on 114 voyages, 21% felt slightly unwell and 7% vomited (Lawther and Griffin, 1988); in genuinely rough conditions the rate approaches everyone aboard (Gahlinger, 2000).

For the full mechanism, the science page has the deep dive.

Seasick soon after you set off

Early in a voyage your body has had no time to adapt to the motion. The CDC Yellow Book calls adaptation, or habituation, the most effective countermeasure, and notes it can be slow to build. So act at the first yawn or cold sweat, before the nausea grows.

1. Move to the middle of the ship, on a low deck. The NHS advises the middle of a boat, and the CDC advises staying away from the bow.
2. Go out on deck and watch the horizon. The CDC lists a horizon view as some protection at sea. If you cannot get outside, lie down, close your eyes and breathe slowly.
3. Keep your head still and put screens and books away. Both the CDC and the NHS advise against reading while the motion lasts.
4. Get cool, fresh air on your face.
5. Skip alcohol and big meals. The CDC says alcohol increases motion sickness. Small sips of water and a few plain crackers sit better.
6. Expect a pill taken now to work less well. The CDC says motion sickness medicine works best taken before the motion starts, and once symptoms begin the stomach may not absorb tablets well. If you are already sick, ask the ship's medical centre or a pharmacist what suits you rather than taking extra doses.

Get medical help if you keep being sick and cannot keep fluids down, which the NHS lists as a reason for urgent advice. Vomit with blood in it, or vomit that looks like ground coffee, needs help straight away. On a ship, that means the medical centre.

Car sick but fine on a boat?

That happens, and it is not in your head. Motion sickness comes from your inner ear and your eyes disagreeing, and each vehicle sets up that disagreement in its own way. The CDC Yellow Book also notes that adaptation is often specific to one kind of motion, so being used to one does not carry over to another. Four differences can explain it.

• Where your eyes are. In a car, passengers often look down at a phone or at the seat in front. On deck, you are usually looking out at the water. The CDC lists a view of the horizon as some protection on ships and in cars.
• The shape of the motion. A car brakes, accelerates and turns again and again. A large stabilized ship in calm water moves slowly, and often not much.
• Time to adapt. A car trip often ends before your body has had a chance to adjust. A voyage lasts hours or days, which gives habituation more time.
• The conditions so far. If your sailing has been on big ships in calm water, you have not met the sea at its worst. In rough seas, the rate of motion sickness approaches everyone aboard (Gahlinger, 2000).

So being fine at sea so far is a good sign, not a promise. Before a rough crossing or a first trip on a small boat, plan as if it could get you: a midship spot on a low deck, eyes on the horizon, and any medicine taken before you sail, as the label says. The reverse happens too. Some people are fine in a car and sick on a ship, because slow, long-lasting motion is a different trigger. Car sickness itself has its own guide.

Sources for these two sections: CDC Yellow Book, motion sickness; NHS, motion sickness; NHS, diarrhoea and vomiting; Gahlinger, 2000.

Seasickness in children

Children often get seasick more easily than adults, and younger kids may not say what is wrong: going quiet, pale and yawning is a common first sign. Give them a view of the horizon, keep screens away and keep the cabin cool. Talk to your child's doctor before giving any seasickness medicine.

How long does seasickness last?

For most people, until the motion stops or until the body adapts, whichever comes first. On a day crossing it ends when you step off, with tiredness and a queasy stomach sometimes lingering for an hour or two. On a cruise it usually fades within the first day or two as sea legs develop: the habituation research says a few days are usually needed before a significant level of adaptation is reached, and the symptoms generally ease before that point. Rough weather can bring it back after you thought you were over it.

Does seasickness go away after a while?

Usually, yes. Adaptation is the normal course, and the CDC Yellow Book calls it the most effective countermeasure of all, more effective than any medicine. The catch is that it is slow to build, is specific to the kind of motion, and wears off between voyages, so a regular sailor stays adapted while an annual cruiser starts again each time. A minority of people adapt little and need prevention for the whole trip.

How do you tell if you have seasickness?

The first signs are easy to miss: stomach awareness, feeling warm, yawning, a cold sweat, pale skin and a sudden lack of interest in food or conversation. Nausea follows, then vomiting if the motion continues. Dizziness, headache and a heavy drowsiness are common too. If the symptoms started with the ship's motion and ease when you watch the horizon or go on deck, it is seasickness. Spinning vertigo, hearing changes or symptoms that began before you boarded point to something else and are worth a word with the ship's doctor.

Is it better to lie down when seasick?

Yes, if you cannot get a view of the horizon. Lying flat on your back with your head still cuts the head movements that feed the inner ear, and the CDC lists lying down among the supportive measures once symptoms have started. Close your eyes, breathe slowly and keep the cabin cool. If you can get outside, standing or sitting on deck with your eyes on the horizon is the better option, because it gives your eyes the motion your inner ear is feeling. Below deck at night, lying down wins.

What is the secret to not getting seasick?

Position, view and timing. Position: midship, low deck, facing forward. View: the horizon whenever you can, and nothing to read. Timing: if you use medicine, take it before you sail as the label directs, because the CDC says it works best before exposure and is poorly absorbed once nausea has started. Add sleep the night before, no alcohol, light meals, and act at the first yawn rather than the first wave of nausea. The real secret is the stack: small, boring things done together.

What percentage of people get seasick on a cruise?

It depends on the sea, not the brochure. The largest survey we have counts passengers at sea rather than cruise passengers specifically: of 20,029 ferry passengers on 114 voyages, 7% vomited and 21% felt slightly unwell (Lawther and Griffin, 1988). Modern cruise ships are larger and stabilised, so calm-water rates are lower, and in rough seas the share affected approaches everyone aboard (Gahlinger, 2000). We have not found a published survey that counts cruise passengers alone, so a single number quoted for cruises is usually an estimate.

What calms seasickness?

Fresh air, the horizon, stillness and time. Go on deck, fix your eyes on the horizon, keep your head still, and sip water rather than gulping it. Plain crackers or dry toast settle some stomachs. Ginger takes the edge off queasiness for some people, though the CDC rates the evidence for it weak. Acupressure bands have not beaten placebo in trials but are harmless if you find them calming. Sound therapy through headphones asks nothing of your eyes, which is why it suits an inside cabin: Dizzout is drug-free, and Dizzout states relief in about 90 seconds.

Natural ways to prevent seasickness

Everything on this list is free or nearly free, and works best started before the ship does.

• Book midship on a low deck, the part of the ship that moves least.
• Spend the first hours on deck with your eyes on the horizon, so your body starts adapting with the best possible view.
• Sleep well and skip alcohol the night before. The CDC lists both sleep loss and alcohol among the things that make motion sickness worse.
• Eat light and often. A plain meal before boarding, small snacks on board, water in sips.
• Keep your head still and your eyes up. No reading or scrolling below deck while the sea is up.
• Ginger in advance, if you want to try it. The evidence is weak but it is drug-free; ask a pharmacist first if you are pregnant or take regular medicine.
• Practise slow breathing with a longer exhale than inhale; it is the one thing you can do in any cabin.

The wider list, with what the trials found for each, is in natural remedies for motion sickness.

Sea sickness medication and boat sickness tablets

The usual sea sickness medication is an antihistamine tablet, such as meclizine or dimenhydrinate, or a scopolamine patch. There is no single best motion sickness medicine for boats: the CDC Yellow Book matches the choice to the trip.

• Up to about 6 hours, mild to moderate seas: meclizine or dimenhydrinate tablets. Promethazine for intense motion.
• Longer trips: meclizine or dimenhydrinate for mild motion, the scopolamine patch for moderate to rough seas.
• Timing: take any of them before you sail, as the label directs. The CDC says they work best before exposure, and a tablet swallowed once you feel sick may not be absorbed.
• Side effects: drowsiness is the most common. Try a dose at home before the trip, since people react differently.
• Not these: the newer non-drowsy allergy tablets, such as cetirizine, fexofenadine and loratadine, do not work for motion sickness.
• The patch: never cut it to change the dose, and it is not for people with glaucoma or at risk of urinary retention.

In the UK, the NHS says a pharmacist can recommend tablets, patches for adults and children over 10, and bands. Ask a doctor before giving any seasickness medicine to a child or if you are pregnant. Label by label detail is in the medication guide, and the timing planner turns the label times into clock times for your sailing.

Why sound therapy works on a ship

Precisely calibrated audio through whatever headphones you have on. It asks nothing of your eyes, which matters below deck, in an inside cabin, at night, or lying down with them shut, where the horizon trick everyone recommends simply is not available. Dizzout states relief in about 90 seconds.

No drugs means no drowsiness. You can use it before boarding, when symptoms hit, or anywhere in between.

Still rocking after you are back on land? That is usually land sickness, and it tends to fade within hours to a couple of days.

Sailing a specific ship?

Each major cruise ship has its own motion profile. The newest Icon-class ships from Royal Caribbean barely feel the sea; older mid-size vessels move more. Browse a few:

Browse all ships at /motion-sickness/cruise.

Common questions

This content is for general information only and is not medical advice. Dizzout is a wellness app and is not intended to diagnose, treat, cure or prevent any condition. Speak to a doctor if symptoms are severe or persistent.

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