Hundreds of people claim a drug used to help people quit smoking has given them some serious side effects.

Dana Roy says she tried to slit her wrists while she was taking the drug Champix. She says "I looked down at the sink and this knife was sitting here, and I picked it up and cut both my wrists".

Roy says "I had such an overwhelming feeling of anxiety; I just wanted the feeling to go away".

Roy's medication did come with an information sheet that described common side effects such as nausea and trouble sleeping. It also said "tell your doctor if you experience agitation, depressed mood or suicidal thoughts" the sheet also says "it's not known if these symptoms are related to Champix".

There have been over five-hundred similar adverse events reported to Health Canada but so far no one has been able to make a direct link. There's no evidence to prove that Champix causes the side effects.

Calgary psychiatrist and addictions specialist Dr. William White says Champix is an effective drug which he continues to prescribe. He says he has never seen a reaction among his patients, a group that he would consider to be at higher risk of side effects because they have pre-existing psychiatric conditions.

The drug company Pfizer which makes Champix says the side effects of quitting smoking can also be disconcerting to people. They include anxiety, restlessness and depressed mood.

Pfizer says "It is currently working with Health Canada to update the prescribing information to reflect current safety information".

Health Canada has strengthened the safety information and labeling of the drug and it is looking at it again.