Skip to main content

Chantix side effects and how to avoid them

Chantix side effects include nausea, appetite change, and vivid dreams. Learn more about these side effects and the Chantix recall.

Common Chantix side effects | Nausea | Appetite change | Vivid dreams | Serious side effects | Depression | Cardiovascular side effects | How long do side effects last? | Warnings | Interactions | How to avoid side effects

Smoking cessation has an array of benefits, including reductions in cancer rates, lung disease, heart attack and stroke risk, and all-cause mortality. Succeeding with a quit attempt can be exceedingly difficult, but the unique smoking cessation medication Chantix (varenicline) can more than double the chance of success. Zyban (bupropion) and over-the-counter nicotine replacement therapies, such as Nicoderm CQ nicotine patches, are a couple of the alternative options to help quit smoking

Chantix attaches to nicotine receptors in the brain as a partial agonist, both reducing the craving for nicotine and blocking the pleasure of smoking. While it is enticing to double the chance of achieving the array of smoke-free health benefits, there are some side effects with Chantix which must be considered. This article will explore Chantix side effects and provide tips for avoiding them.

Common side effects of Chantix

  • Nausea, vomiting, upset stomach, appetite change, or abdominal pain
  • Flatulence, diarrhea, or constipation
  • Dry mouth or taste disturbance
  • Insomnia, abnormal dreams, or sleep disorder
  • Malaise, fatigue, or somnolence (sleepiness)
  • Headache
  • Emotional disturbance
  • Shortness of breath or respiratory disorders
  • Skin rash

Nausea

The most common adverse reaction to Chantix is nausea, which studies have estimated to occur in about 25% of individuals. Typically, the nausea is mild, occurs within the first two weeks, and often resolves with time. Persistent or worsening nausea or if nausea is accompanied by vomiting, consult your prescriber for medical advice.

Appetite change

One of the biggest concerns amongst smokers who are considering quitting is that they will gain weight. While weight gain after stopping smoking averages five to 10 pounds, individual experiences can vary considerably. In fact, about 20% of those who quit may lose weight. 

Based on the concern regarding weight gain, interest in whether Chantix mitigates or worsens this risk is natural. Chantix users may actually experience either an increase or decrease in appetite, but neither one occurs in more than 5% of users. Ultimately, Chantix does not seem to significantly affect the chance of weight gain with smoking cessation.

Vivid dreams and nightmares

A variety of sleep-related disturbances have been described with Chantix. These disturbances can range from unusual dreams to trouble sleeping. Most commonly, abnormal dreams are experienced by about 10% of those taking the drug, and nightmares or sleep disorders are reported by another 1% to 3%. Small numbers of case reports have described sleepwalking that involved harmful activities. 

Sleep problems may also be an aspect of nicotine withdrawal after quitting smoking. Withdrawal symptoms after smoking cessation may also include cravings to smoke, increased appetite, sadness, irritability, restlessness, and difficulty concentrating.

Serious side effects of Chantix

  • Depression or neuropsychiatric disorder
  • Suicidal behavior or thoughts
  • Homicidal thoughts
  • Hypersensitivity allergic reaction or angioedema (swelling of the face or body)
  • Serious skin reactions such as Stevens-Johnson Syndrome (includes blisters and peeling skin) or erythema multiforme
  • Arrhythmia (heart rhythm problem), heart attack, stroke, or angina (chest discomfort)
  • Seizure
  • Photosensitivity (light sensitivity)
  • Vision changes
  • Anemia or thrombocytopenia (low platelet or clotting cell count)
  • Kidney stones or kidney failure
  • Gastrointestinal bleeding
  • Pancreatitis (pancreas inflammation)
  • Hypokalemia (low potassium level)

Depression

Case reports of depressed mood and even suicidal thoughts and aggressive behavior came to light after the release of Chantix. The Food and Drug Administration (FDA) responded by adding a black box warning on Chantix in 2009 about this risk. A subsequent study examined these potential concerns in detail and did not find an elevated risk of these adverse effects compared to other smoking cessation medications or even a placebo. The FDA removed the black box warning from Chantix in 2016.

Cardiovascular side effects

Chantix has labeling that warns about use by those with known cardiovascular disease. The labeling arose due to some study data showing a small increased risk of life-threatening cardiovascular events with Chantix. An analysis of multiple clinical trials did not corroborate this concern, however, as rates of cardiovascular events were similar between those taking and not taking Chantix. Furthermore, the FDA has noted that the benefits and risks of taking Chantix must be considered since smoking cessation is particularly improvement for those with cardiovascular disease.

How long do Chantix side effects last?

The duration of Chantix side effects can vary. Most side effects resolve when the medication is discontinued. In fact, immediate discontinuation is advised if one experiences mood changes while on Chantix. On the contrary, mild nausea may improve with time alone, even if Chantix is continued.

Chantix contraindications and warnings

Chantix is not habit-forming.

Based on the concern for cardiovascular or neurological side effects, an overdose of Chantix warrants emergency medical attention and a call to the Poison Help line at 1-800-222-1222. Case reports are limited, but one report lists a fatality with overdose, although additional factors were present.

Anyone with a history of hypersensitivity (allergy) to varenicline should not take Chantix. Cautious consideration and discussion with a healthcare professional are needed before taking Chantix for anyone with a seizure history or risk, cardiovascular disease, psychiatric illness, alcohol use, or renal impairment (kidney disease) with a creatinine clearance of less than 30 mL/minute. Age is another consideration as Chantix is only used in those 17 years and older. Lack of clinical trials in pregnancy and breastfeeding means that caution is needed before using the drug in these circumstances.

A recall on all brand-name Chantix was announced by Pfizer in 2021.

Chantix interactions

Medications that raise the risk of seizure are the primary drug interaction of note for Chantix and may need to be avoided or modified when taking Chantix. Examples of these medications include amifampridine, bupropion, and tramadol.

Concurrent nicotine use may increase the risk of headaches, nausea, vomiting, and dizziness.

Chantix may increase the effects of alcohol by lowering alcohol tolerance. Therefore, alcohol use should be curtailed or avoided.

How to avoid Chantix side effects

  1. Carefully follow the instructions on taking Chantix, as the dosing is typically initiated at a low dose of 0.5 mg once daily for three days and then twice daily for four days, before increasing to the full 1 mg dose twice daily thereafter. This titration may help to avoid side effects at initiation. If you’re unsure how to take Chantix, ask a pharmacist to review the medication guide with you. The manufacturer also provides drug information.
  2. Set a quit date for stopping smoking, often on day eight of Chantix therapy. However, some healthcare professionals may advise gradual discontinuation or a flexible quit date.
  3. Chantix is usually taken for at least 12 weeks of treatment, but the end of treatment may be individualized.
  4. Take the medication with a full glass of water after a meal to potentially reduce the chance of nausea.
  5. Carefully review your health history with the treating medical provider, especially taking time to discuss any history of cardiovascular or mental health problems.
  6. Avoid concurrent alcohol use.
  7. Immediately tell your healthcare provider or seek medical attention if any mood changes, suicidal ideation, chest pain, or harmful sleep disorders are experienced while taking Chantix.