Chantix is a pill that does not contain nicotine but rather acts by blocking receptors that react to nicotine, which helps reduce cravings, according to the U.S. National Library of Medicine.
The drug appears to be both fairly safe and effective. A recent study in the journal PLOS ONE found that when Chantix was combined with counseling it was more effective in getting smokers to quit than counseling alone.
Varenicline is not a benign drug, with side effects that include:
nausea
constipation
diarrhea
gas
abdominal pain
vomiting
heartburn
bad taste in the mouth
dry mouth
increased or decreased appetite
toothache
trouble falling asleep or staying asleep
unusual dreams or nightmares
headache
lack of energy
back, joint, or muscle pain
abnormal menstrual cycles
Some side effects can be more serious, namely:
swelling of the face, throat, tongue, lips, gums, eyes, neck, hands, arms, feet, ankles, or lower legs
hoarseness
difficulty swallowing or breathing
rash
swollen, red, peeling, or blistering skin
blisters in the mouth
pain, squeezing or pressure in the chest
pain or discomfort in one or both arms, back, neck, jaw, or stomach
shortness of breath
sweating
nausea, vomiting, or lightheadedness with chest pain
slow or difficult speech
sudden weakness or numbness of an arm or leg, especially on one side of the body
calf pain while walking
seizures
sleepwalking
In clinical studies, those taking Chantix were more likely to have a heart attack, stroke or other serious problems with their heart or blood vessels.
Talk to your doctor about the risks and benefits of taking Chantix, especially if you have or ever had heart or blood vessel disease.
In 2021, Pfizer, the maker of Chantix, recalled the drug because of unacceptable levels of nitrosamine, a naturally occurring chemical that can cause cancer. But by the middle of 2022, the FDA announced that Chantix was safe to take as the levels of nitrosamine were now at acceptable levels.
