From the Guidelines
Chantix (varenicline) can cause several side effects, including nausea, insomnia, abnormal dreams, headache, and fatigue, as reported in a 2021 study published in JAMA 1. These side effects are common and can affect a significant portion of users.
- Nausea is one of the most common side effects, affecting about 30% of users.
- Other common side effects include trouble sleeping, vivid dreams, headaches, and constipation.
- Some people may experience mood changes like irritability, depression, or anxiety.
- More serious but less common side effects include cardiovascular events, seizures, allergic reactions, and suicidal thoughts or behaviors. According to the 2021 study, there is no statistically significant difference in cardiovascular adverse events or cardiovascular severe adverse events with varenicline use 1. Additionally, no statistically significant increase in neuropsychiatric adverse events, including depression, suicidal ideation, and suicide attempt, was found across several systematic reviews 1. The FDA previously had a black box warning about neuropsychiatric effects, but this was removed in 2016 after further studies. Most side effects are mild to moderate and often improve after the first few weeks of treatment, and taking Chantix with food and a full glass of water can help reduce nausea 1. If you experience severe side effects, particularly mood changes or suicidal thoughts, contact your healthcare provider immediately. The medication works by binding to nicotine receptors in the brain, reducing both the pleasure from smoking and withdrawal symptoms, which explains why it can affect mood and sleep patterns. It is essential to weigh the benefits of Chantix against the potential risks and to monitor patients for any adverse effects, especially those with a history of mental health conditions or seizure risks 1.
From the FDA Drug Label
The most common side effects of varenicline tablets include: nausea sleep problems (trouble sleeping or vivid, unusual, or strange dreams) constipation gas vomiting Serious side effects of varenicline tablets may include: Seizures. New or worse heart or blood vessel (cardiovascular) problems, mostly in people, who already have cardiovascular problems. Sleepwalking can happen with varenicline tablets, and can sometimes lead to behavior that is harmful to you or other people, or to property. Allergic reactions can happen with varenicline tablets. Serious skin reactions, including rash, swelling, redness, and peeling of the skin.
The possible side effects of varenicline tablets include:
- Common side effects: nausea, sleep problems, constipation, gas, vomiting
- Serious side effects: seizures, new or worse heart or blood vessel problems, sleepwalking, allergic reactions, serious skin reactions 2
From the Research
Side Effects of Chantix
- Chantix, also known as varenicline, has been associated with various side effects, including neuropsychiatric adverse events such as suicidal thoughts and behavior, depression, and aggression/agitation 3, 4.
- However, studies have shown that the risk of these adverse events is not significantly increased with varenicline compared to other smoking cessation treatments such as nicotine replacement therapy and bupropion 3, 4, 5.
- A cohort study found that the hazard ratio for self-harm among people prescribed varenicline was 1.12 (95% CI 0.67 to 1.88) compared to nicotine replacement products, and 1.17 (0.59 to 2.32) compared to bupropion 3.
- Another study found that varenicline increased the risk of nausea (odds ratio=3.69,95% CI=3.03-4.48) but not rates of suicidal events, depression, or aggression/agitation 4.
- A systematic review of postmarketing analyses, case reports, clinical trials, and observational studies found that the evidence suggests varenicline is not associated with an increased risk of suicidal outcomes, or if it is, the effect is very small 5.
Common Side Effects
- Nausea
- Neuropsychiatric adverse events (such as suicidal thoughts and behavior, depression, and aggression/agitation), although the risk is not significantly increased compared to other smoking cessation treatments
- Self-harm, although the risk is not significantly increased compared to other smoking cessation treatments
Rare Side Effects
- Suicidal outcomes, although the evidence suggests that varenicline is not associated with an increased risk of these outcomes, or if it is, the effect is very small 5.