Trains are generally one of the better options for motion sickness sufferers, however many people experience discomfort when seated facing against the direction of travel.
Some travelers also report feeling unwell on high-speed tilting trains (such as Britain's Pendolino
services) and, in particular, on the Eurostar service linking the UK to Belgium and France though the underwater tunnel under the English Channel.
For those prone to motion sickness, a forward facing seat is crucial. Most trains have both forward and backward facing seats (with the honorable exception of Japan's Shinkansen
bullet trains where the seats all face forward - they are automatically turned at the end of every journey!).
Unfortunately, you may have difficulties booking forward facing seats. Often the booking agents simply don't know what the exact configuration of the train will be. And even if you appear to have succeeded in booking forward facing seats, it is common to arrive at your seat to find that it is not, in fact, forward facing after all. If this happens, and nearby forward facing seats are occupied, ask to swap with someone. The threat of a sick fellow passenger is usually enough to make people agree to move. But do be sensitive - you may have picked a fellow sufferer. You can also ask the train conductor or onboard manager for help. Clearly it is as much in his/her interests as yours that you are not physically sick on the train!
The smoothest and most stable part of any train is towards the center of the middle carriage. The 'sideways' visual stimulation that you get from the window when sitting in an aisle seat can be uncomfortable, so sit in a window seat and try to look forwards along the length of the train as much as possible. Alternatively, put your head back, close your eyes and try to 'tune out'. Headphones and soothing music may help. But don't miss your stop!
As with other forms of transport, reading may trigger sickness, so is best avoided. Many long distance rail services now have a 'quiet coach' which you will find more relaxing if you wish to sleep.
Good ventilation is very important, so open a window if possible, or stand by the train doors at station stops for a fresh air 'fix'. Move seats or carriages if someone near you is eating strong or unpleasant-smelling food, or wearing a heavy perfume. If you find the carriage too hot or too cold talk to the conductor or train manager. He or she may be able to adjust the temperature control for you.
Walking through the carriage, and especially between carriages, can bring on nausea very quickly, so stay in your seat as much as possible. Eat lightly and take regular sips from a bottle of water or flask of ginger or peppermint tea.
If you do become nauseous and can't bear to stay in your seat then make your way to the vestibule at the end of the carriage. In the vestibule, hold on to one of the grab rails, close your eyes and try to move with the motion of the train. You may look slightly odd, but it can have a very positive effect on how you feel. If you choose the correct end of the carriage, you'll also have the advantage of being positioned next to the restroom, should you require it.
If the worst comes to the worst, and you can't bear it any longer, get off at the next station and wait for the following train. Hopefully you'll be feeling better by the time it arrives!