Health Canada has issued a warning about Zyban, a drug used to help people quit smoking and treat depression at the same time.

The department has directed drug maker Glaxo SmithKline to issue special safety information about Zyban, also sold as Wellbutrin SR.

The bulletin tells doctors about the number of Canadians who have reported side effects since the drug hit the market three years ago.

In all, 1,127 adverse reactions have been reported, including 19 deaths. Half of the reactions are considered serious, from skin rashes to seizures.

There is no clear evidence Zyban or Wellbutrin are responsible for the deaths, but the letter suggests growing concern.

"They have detected a significant signal for concern and they want to alert doctors of this issue," notes Dr. James Wright who evaluates drugs for the British Columbia government.

Zyban works on the brain to cut the craving for nicotine. It also helps combat depression.

The letter reminds doctors that certain people should not take the drug:

• individuals with a history of seizures
• people who have eating disorders
• anyone taking another antidepressant

Wright says there should be a drop in the number of prescriptions. If not, Health Canada should act.

"I think they should be...considering whether this drug should be either restricted or pulled from the market."

Medical authorities in Germany, Britain and Australia have also raised concerns about bad reactions. They are all monitoring the drug's safety record.