Seasickness, and what the CDC actually says

Surprise one: the best countermeasure is not a drug

The CDC's own wording, and I did not expect it to be this blunt: "Habituation is the most effective countermeasure — even more than any medication — but can be slow to acquire."

Habituation means your body adjusting to the motion. Which is the scientific way of saying what experienced cruisers say: by day three you stop noticing. That is not folklore, it is the CDC's published position.

Surprise two: timing beats everything

The CDC publishes that motion sickness "medication is most effective when taken before exposure, rather than after the onset of symptoms."

This is where most people go wrong. They wait until they feel green, then take something, then decide it does not work. Taken after the fact, it largely does not. Whatever you plan to use, the plan starts before you sail, not after you feel it.

What the CDC lists that costs nothing

These are the behavioural countermeasures published in the CDC's motion sickness chapter:

• Get a visual horizon reference. Look at the horizon, not at the deck.
• Do not read, and avoid visual scanning. The phone is part of this.
• Avoid head movements. Turning to look at things makes it worse.
• Lie down, face up. Aligning your body with the motion helps.
• Avoid the locations of maximum motion. On a ship that means high and far forward or far aft. Low and midships moves least.
• Be in control. Drivers get carsick less than passengers, and the same principle applies at sea — being able to see and anticipate the motion helps.
• Controlled breathing. Slow and deliberate.

Royal Caribbean publishes the same cabin advice in its own words: choose a cabin lower down and closer to the centre of the ship, and focus on the horizon.

The medications, as officially described

The CDC names scopolamine, and the antihistamines dimenhydrinate, meclizine and promethazine. It also notes that ondansetron and granisetron — drugs some people know from other kinds of nausea — are not effective for motion sickness.

On drowsiness, the CDC ranks them: "Scopolamine is slightly less sedating than dimenhydrinate or meclizine, whereas promethazine is the most sedating."

And one that catches people out: the newer non-drowsy allergy antihistamines do not work here. The CDC explains why — they "are designed to avoid penetration into the brain," which is exactly where they would need to act.

Two more published cautions on the patch: the CDC states scopolamine "should not be used in travelers with glaucoma or who are at risk of prostatic urinary retention," and that the patch "should never be cut up" to vary the dose, because cutting it disrupts how the drug is released. In the US it is prescription-only, so this is a conversation with your own doctor before you sail.

If you forget to pack anything

Celebrity publishes that "at the guest relations desk onboard, you'll find tablets that will help combat seasickness." What they do not publish is whether those tablets are free, or what they are. So ask, and do not plan around them.

This is general information from published CDC and FDA sources, not medical advice, and it is not a recommendation to take any particular medication. Medicines interact with other medicines and with existing conditions. Talk to your own doctor or pharmacist before you sail.