How Does Chantix Work?

Published August 1st, 2020 by Corey Riley
Fact Checked by
Erik Rivera
Medically Reviewed:
Dr. Angel Rivera
Updated Date: May 17th, 2021

According to the World Health Organization, tobacco kills up to half of the people who use it and approximately eight million people each year. While all forms of tobacco use are harmful, cigarette smoking is the most common form of tobacco use around the world. Even when people know and understand the risks associated with tobacco use, they still struggle to stop using tobacco products. In fact, without support, only four percent of attempts to quit using tobacco succeed. Smokers who want to quit using cigarettes have often made many attempts to quit without success, which is why nicotine replacement products like Nicorette gum and Chantix, a prescription drug designed to help people quit smoking, are so popular. If you’re considering quitting smoking using Chantix, it’s important to understand how to properly use the medication and how it can benefit you. So, how does Chantix work?

What is Chantix?

Chantix, also known under the generic name varenicline, is a prescription smoking cessation aid that has been prescribed to more than 13 million people. Unlike gums and patches that help people quit smoking, Chantix does not contain any nicotine and is only available by prescription medicine. Although Chantix helps people quit smoking, it should be used in conjunction with behavioral changes and counseling or other support in order to be effective. Chantix was first approved by the U.S. Food and Drug Administration (FDA) in 2006.

How does nicotine affect brain chemistry?

The reason why tobacco products are so addictive is a chemical called nicotine that is found in cigarettes and other tobacco products. Nicotine is a stimulant that provides an immediate jolt of euphoria and energy when ingested because it changes your brain chemistry rapidly. The effects of nicotine start setting in within seven seconds of starting to smoke a cigarette. Nicotine closely mimics the size and shape of a neurotransmitter called acetylcholine, which influences body functions like breathing, learning, heart rate, and memory. Because nicotine is so similar in size and shape to acetylcholine, it is able to bind to receptors in the brain that are designed to receive acetylcholine. The brain mistakes the nicotine for acetylcholine and begins producing the same effects as it would if acetylcholine was bound to the receptors, and the brain begins to release dopamine. Dopamine is a neurotransmitter associated with pleasure and reward, and it is believed that this process is the reason why certain substances, like nicotine, are highly addictive. Because the effects of nicotine wear off quickly, people find themselves smoking more and more throughout the day to produce the same effects and avoid nicotine withdrawal.

How does Chantix work?

Chantix works by binding to nicotine receptors in the brain, which prevents nicotine from binding to these same receptors. The receptors notice that something similar to nicotine is bound to them, so they begin to produce dopamine at a lower volume than they would if nicotine was attached. People who smoke would compare the amount of dopamine released to a low or medium dose of nicotine, and the feeling lasts for several hours, until Chantix wears off. Chantix helps people avoid the withdrawal symptoms that accompany quitting smoking, which makes quitting easier, but it also reduces the power that cigarettes hold. If you smoke while taking Chantix, the nicotine will not be able to bind to its receptors because Chantix has already bound to them, which means smoking will not be a rewarding experience. This helps to break the brain’s association between smoking, nicotine, and reward, making quitting easier over time. 

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How is Chantix used?

Chantix is a three to six month treatment program that can help people quit smoking. The medication should be taken after eating and with a full glass of water. When people first start taking Chantix, they will gradually increase their dose over the first seven days. According to the manufacturer, there are three ways to quit smoking using Chantix: the fixed quit approach, the flexible quit approach, and the gradual quit approach.

Fixed quit approach

The fixed quit approach is best suited to people who are ready to quit now and want to put their cigarettes down for good in one week. Using the fixed quit approach, smokers start taking Chantix and may continue smoking for the first week while using the medication. After one week, the individual stops smoking cigarettes and continues to use Chantix for the next 11 weeks.  

Flexible quit approach

The flexible quit approach is most appropriate for smokers who know that they want to quit smoking but would like more flexibility in choosing when. Under the flexible quit approach, smokers begin taking Chantix and choose a date within a month of starting the medication to stop smoking. The person may choose to keep smoking up to their quit date, at which time they stop smoking and continue taking Chantix. Chantix is taken for a total of 12 weeks.

Gradual quit approach

The gradual quit approach is best suited to those who think they might want to quit smoking but do not feel willing or able to quit right away. Under the gradual quit approach, smokers start taking Chantix and then gradually reduce the amount of cigarettes they smoke over the course of 12 weeks. It is recommended that smokers using the gradual quit approach cut the amount of smoking in half during the first four weeks of treatment and then in half again by week eight. Individuals then further reduce their smoking to quit completely within 12 weeks. Using the gradual quit approach, people take Chantix for a total of 24 weeks, including while reducing and then quitting smoking during the first 12 weeks and for 12 more weeks after quitting. 

Is Chantix effective?

The effectiveness of Chantix has been demonstrated by several studies, but it varies depending on which of the three approaches is used to quit smoking. Chantix was found to be 44 percent effective at weeks 9 to 12 among smokers who quit using the fixed quit approach, while only 18 percent of those taking a sugar pill were able to quit by that time. Using the flexible quit approach, 54 percent of smokers taking Chantix had quit by weeks 9 to 12, compared to 19 percent of people who were taking a sugar pill. Approximately 32 percent of smokers using the gradual quit approach had quit by weeks 15 to 24, compared to 7 percent of smokers taking a sugar pill. Regardless of which approach is used, Chantix has not been found to be effective in patients ages 16 years of age and younger who are trying to quit smoking. 

Compared to other smoking cessation methods, Chantix was shown to be more effective than Zyban and Bupropion as a smoking cessation aid, reporting a 22 percent success rate and 16 percent rate, respectively, in two clinical trials when correct medication guides were followed. Over the course of one year, rates of smoking cessation for Chantix (19 percent) were comparable to other methods, including the nicotine patch (21 percent) and a combination of the patch and lozenges (20 percent). 

What side effects of Chantix?

There are multiple adverse effects associated with Chantix. The most commonly experienced side effects, which do not require medical attention unless they last for a long time or get worse, include:

  • Nausea
  • Vomiting
  • Gas
  • Trouble sleeping
  • Changes in taste
  • Headache
  • Drowsiness
  • Constipation
  • Unusual dreams

Other common side effects are more serious and require medical attention. Stop taking Chantix and tell your doctor or healthcare provider right away if you experience any of the following side effects:

  • Burning feeling in the feet or toes
  • Unusual pain in the legs while walking
  • Seizure
  • Signs of a stroke
    • Weakness on one side
    • Sudden vision changes
    • Trouble speaking
    • Confusion
  • Signs of a heart attack
    • Pain in the chest, jaw, or left arm
    • Shortness of breath
    • Unusual sweating
  • Behavior that is harmful to yourself, other people, or property

Are there any risks associated with Chantix?

According to the Pharmaceutical company Pfizer, though rare, Chantix can cause significant and serious changes to a person’s mental state or mood, even after the individual stops taking the medication so use caution. Patients are more likely to experience changes to their mood or mental state if they drink alcohol while taking Chantix. Quitting smoking can also contribute to mood or mental changes, so it is important to be aware of changes you may feel. You should stop taking Chantix and tell your doctor or pharmacist immediately if you begin experiencing symptoms of mood or mental disruption such as depression, suicidal thoughts or suicidal ideation, agitation, aggression, or other behaviors or thoughts that are unusual. Make sure you tell your doctor if you have a history of a depressed mood or other mental health problems prior to taking Chantix so that you can determine together if Chantix is right for you. 


Published August 1st, 2020 by Corey Riley
Fact Checked by
Erik Rivera
Medically Reviewed:
Dr. Angel Rivera
Updated Date: May 17th, 2021

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