Dr. What Are The Dangers Of A 50 Percent Blockage

Dr. what are the dangers of a 50 percent blockage in a carotid artery? does is cause chronic headaches, mood swings? my friend is taking meclizine 25mg twice daily with out she has mood swings continually complain of severe head aches. should a second opinion be feasible or is surgery required to clear the blockage in I her left artery. I do know this is the main blood supply to the brain and could very easily cause a stroke or worse she is not a believer: how can I convince her to get a second opinion?