To prevent nausea and vomiting, you can take the over-the-counter anti-nausea medicine meclizine (also sold under the brand names Dramamine II or Bonine) an hour before taking emergency contraception (EC) pills. Note that these anti-nausea medications might make you drowsy.
If you end up puking within an hour of taking EC pills, you may want to take it again in case your body didn’t absorb the hormones yet.