ATLANTA , Georgia ( CNN ) -- `` Cloverfield '' is the first adrenaline-pumping monster hit of the year , bringing in more than $ 40 million dollars on its opening weekend . The thriller is told from the point of view of five young New Yorkers using their handheld camera . But for some viewers , being `` part '' of the movie is making them sick -- literally . Theaters showing `` Cloverfield '' are posting warnings of possible motion sickness . One blogger on the popular movie database IMDB.com said , `` I had to get up and leave the theater for nearly 20 minutes just to keep from hurling . '' Other moviegoers have reported being nauseated and dizzy . Most viewers are unaffected by the film , but for those who are , experts say the problem is in their heads . `` This is a classic case of vertigo , '' said Dr. Michael G. Stewart , chairman of otorhinolaryngology ( ear , nose and throat medicine ) at NewYork-Presbyterian Hospital/Weil Cornell Medical Center . `` You can look around and feel like things are moving , when they are n't . '' Vertigo is caused when a person 's balance system gets confused . Your body feels a strong visual sensation of movement but in reality , you are n't moving at all . The disconnect confuses your brain sensors and can cause dizziness and nausea , Stewart said . Watch Dr. Gupta explain what 's making viewers sick » . AMC theaters across the country have posted signs warning moviegoers of potential `` side effects associated with motion sickness similar to riding a roller-coaster . '' So why does the film style affect some viewers and not others ? `` People have different levels of susceptibility , similar to how some people can not ride on a small boat without getting sick , '' Stewart said . `` It 's just a natural variation . '' The good news is , experiencing vertigo is rare for most people . So if you are itching to see `` Cloverfield '' but are worried you might get sick , experts recommend taking a dose of over-the-counter anti-vertigo medicine , sold under such brand names as Bonine and Dramamine II . `` It might not protect you from all the symptoms , but it could , and it certainly ca n't hurt , '' Stewart said . Another tip is to briefly close your eyes during the movie . It may be enough to recalibrate your sensors and soothe your symptoms long enough to finish the movie . And if you 're really concerned , just wait to rent the movie . `` A person would be fine watching from home , '' Stewart said . `` When you are on your couch , you have perspective around the screen so your mind knows the movie is moving and the room is n't . '' E-mail to a friend . Danielle Dellorto is an associate producer with CNN Medical News .
Some moviegoers shocked by shaky camera work of ` ` , '' said , dizziness are symptoms of weakness , a disruption of the body . The problem is body has strong visual sensation of movement while you are n't .