Meclizine
"I have re-occurring bouts of vertigo about 3-4 times a year.  It seldom lasts more than 14-20 hours but is severe at times, spinning surroundings, and feeling of falling backwards.  Usually the drowsy feeling stays with me for 2 days.  I have tried the natural remedies but find that Bonine or Meclizine works the best for me. I have had a hard time to find it over the counter the past year."