Paul Stamler from the States makes some suggestions:

Dizzy no more!

I'm one of those folks whose semicircular canals go off easily.  Most of the time my problems have been with contra, not English, but I've sometimes had trouble with ECD as well.

I've found four ways to minimize the problem:

  1. The tried-and-true “look in your partner's eyes when you swing”.  Note that this only applies to contra; for me, at least, it doesn't work in English.  Why?  Because in contra swings are done fairly close to your partner, and by focusing on your partner's eyes (or neckline, or whatever) you throw the background thoroughly out of focus, so you don't see it going sideways.  In English Country Dance (ECD), on the other hand, turns are done at a greater distance, and the background is less out of focus, and you get dizzy.  Instead, I use Method 2:
  2. On turns, stars, etc., fix your eyes on some fixed object in the room, stay riveted on that object for as long as you can, then snap to a new object.  The idea is to see a succession of stationary scenes, rather than the moving world.  This is an old ballet dancer's trick; watch them spinning on axis, and snapping their heads around suddenly.
  3. Hyper-hydrate -- drink twice as much water as you think you need.  Dehydration seems to make your semicircular canals even more sensitive, possibly disturbing their fluid balance.  If you tend toward low blood sugar, keep a couple of hard candies on hand and pop them as needed.  If you sweat a lot, something salty may help too.
  4. No caffeine.  This is a big sacrifice for me, as I'm a confirmed coffee drinker.  I found this made a huge difference; I stop drinking coffee about 5 hours before the start of a dance evening.  I don't drink alcohol in any meaningful quantities, so I can't testify about that, but my guess is that the same applies to alcohol -- note that both alcohol and caffeine are net dehydrators, so they may relate to Method 3.  I have no idea about the third common stimulant, chocolate.
Those are the things that have helped me a lot.  Previously, I could usually get through about three contra dances before getting dizzed out; now, I can make it through about two-thirds of a typical contra evening before I have to retire, and I can usually pull an entire night of ECD.  Note that people who don't suffer from motion sickness usually have no comprehension or empathy with those who do; the folks who tell you “Oh, it's all in your head” or “Don't worry, it'll go away after a few times” or “Just ignore it” are not helping -- nausea is a hell of a deterrent to dancing.  If you're spin-sensitive, wishing won't make it go away; you need to take positive, concrete preventive steps like the ones above.

Victoria Bestock from Seattle adds:

I thought I'd mention that I became dizzy dancing when I got blended bifocals, and stopped getting dizzy when I started dancing in a pair of distance-only glasses that don't have the reading prescription.  Since many older dancers wear bifocals, this might be a factor for some of them.