Chantix (varenicline) is a prescription medication that helps individuals quit smoking by targeting nicotine receptors in the brain, reducing cravings and the pleasurable effects of smoking. This article discusses its potential long-term side effects.
Neuropsychiatric Side Effects
Neuropsychiatric symptoms were a significant concern with Chantix, leading to a U.S. Food and Drug Administration (FDA) Black Box Warning in 2009. These included changes in mood or behavior, depression, anxiety, agitation, hostility, and suicidal ideation or behavior. The warning was based on postmarketing reports linking the drug to these psychiatric effects.
The EAGLES trial, a large randomized clinical trial involving approximately 8,000 smokers with and without a history of psychiatric disorders, compared Chantix to bupropion, nicotine patch, and placebo. It found that serious neuropsychiatric adverse events with Chantix were not significantly higher than with placebo in patients without a psychiatric disorder history.
In patients with a history of psychiatric illness, more events were reported across all treatment groups, and the incidence was higher for active treatments, including Chantix, compared to placebo. However, the overall risk was lower than initially believed, often comparable to nicotine withdrawal itself. Based on EAGLES results, the FDA removed the Black Box Warning in December 2016. The updated labeling still describes potential side effects on mood, behavior, or thinking.
Cardiovascular Considerations
Chantix’s impact on cardiovascular health, including heart attack, stroke, or other cardiovascular events, has also been investigated. Initial studies suggested a small, increased risk of cardiovascular events, particularly in those with pre-existing cardiovascular disease. For instance, a 2011 FDA communication noted a trial of 700 smokers with cardiovascular disease showed certain events, like heart attack, were reported more frequently in those taking Chantix than placebo.
However, subsequent larger studies, including the EAGLES trial, largely reassured about cardiovascular safety. The EAGLES trial found that major adverse cardiovascular events (defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke) during and after treatment were low and did not differ significantly across treatment groups, including Chantix and placebo. An updated FDA-required meta-analysis also indicated a low overall incidence of major adverse cardiovascular events, with no statistically significant increase in risk for Chantix users compared to placebo.
While some observational studies suggested a small increase in cardiovascular events during treatment, larger trials indicate Chantix does not significantly increase the risk of serious cardiovascular events in the general population of smokers, especially considering the substantial cardiovascular risks of continued smoking. Observed events are often in individuals with pre-existing cardiovascular conditions, highlighting the importance of individual risk assessment.
Other Persistent Side Effects
Beyond neuropsychiatric and cardiovascular effects, some individuals may experience other side effects that could persist during or after Chantix treatment. Sleep disturbances are commonly reported, including insomnia and vivid or abnormal dreams. While these often improve, they can continue for some users.
Gastrointestinal issues are also frequent, with nausea being one of the most common side effects, affecting approximately 30% of users. Other digestive complaints include constipation, gas, and abdominal pain. While typically managed by taking the medication with food, some individuals may experience these issues persistently.
Rare but serious skin reactions, such as blistering, peeling, or severe rashes, have been reported. Although infrequent, any new or worsening skin reactions should be promptly evaluated by a healthcare provider.
When to Seek Medical Advice
Contact your healthcare provider immediately if you experience any concerning or persistent symptoms while taking Chantix. This includes significant changes in mood or behavior, such as new or worsening depression, anxiety, agitation, hostility, or thoughts of self-harm. Prompt medical evaluation is also warranted for severe physical symptoms like new or worsening chest pain, shortness of breath, or any signs of a serious skin reaction.
Do not stop taking Chantix abruptly without consulting your doctor, as this can lead to withdrawal symptoms or a return of smoking urges. Your healthcare provider can assess your symptoms, determine if they are related to the medication, and provide guidance on adjusting your treatment plan or discontinuing the medication safely. Open communication with your doctor ensures effective management of potential side effects as you pursue quitting smoking.