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Quit-smoking drug may cause heart problems

The drug varenicline (brand name Champix), which has been prescribed to thousands of smokers in the UK to help them quit, may increase the risk of heart problems, the US drug watchdog has warned.

What do we know already?

Varenicline is a drug that makes it easier to give up smoking. Launched in 2006, it blocks the pleasant effects of nicotine. People who take it have two to three times the chance of giving up smoking successfully, compared with someone using willpower alone.

Varenicline can cause side effects. More than 1 in 10 people feel sick, have trouble sleeping, get strange dreams, or get a headache. The UK's drug watchdog has warned that some people get mood changes while taking varenicline, with some people becoming so depressed they think about suicide. However, a study published in late 2009 didn't find any link between varenicline and suicidal thoughts.

Now, the US Food and Drug Administration (FDA) has warned that varenicline may increase the risk of heart problems.

What does the warning say?

Varenicline seems to slightly increase the risk of a heart attack, or of needing surgery to restore blood flow to the heart.

In a year-long study of people trying to give up smoking, 2 in 100 people taking varenicline had a heart attack, compared with 1 in 100 people taking an inactive placebo. And just over 2 in 100 people taking varenicline needed surgery to widen an artery and restore the blood flow to their heart, compared with 1 in 100 people taking a placebo.

None of the people who had heart attacks died.

How reliable is the research?

The study looked at 700 people. Slightly more people got heart problems while taking varenicline, but heart attacks aren't very common. When looking at rare events, it's hard to tell the difference between a real increase in risk and random variation. We can't be sure the results weren't a statistical fluke without studies looking at more people.

The FDA has asked Pfizer, the drug's manufacturer, to combine the results from all the studies looking at varenicline. This should give us a better idea of the side effects varenicline can cause.

Where does the warning come from?

The warning came from the FDA, which regulates drugs in the US. The warning is based on a good-quality randomised controlled trial.

What should I do now?

Smoking causes lots of health problems, including cancer, damage to blood vessels, and heart attacks. Even if varenicline does have some risks, they may be outweighed by the benefits of stopping smoking. Your doctor can help you weigh up the risks and benefits.

There are also alternative treatments that can help you give up smoking, such as the drug bupropion and nicotine replacement products, which include patches and gum. The NHS offers a smoking helpline, which smokers and their families can call for free advice. It's open from 7 a.m. to 11 p.m. every day. The number is 0800 022 4 332.

If you're taking varenicline and you start to feel agitated or get changes in your mood, see your doctor straight away. You can report side effects of varenicline, or any drug, to the UK drug regulator at their website (


FDA Drug Safety Communication. Chantix (varenicline) may increase the risk of certain cardiovascular adverse events in patients with cardiovascular disease. (accessed on 21 June 2011).

Jun 21, 2011