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What does Chantix (Varenicline) do to your body?

Emily Gadd

An orange prescription lying on its side, with green capsules spilling out onto the ground.

Jul 13, 2022

In This Article

Chantix (also known by its generic name, varenicline) is a nicotine-free prescription drug that can help you quit smoking.

According to its manufacturers, Chantix binds to the receptors in your brain where nicotine normally binds. Because of the drug’s presence, nicotine can’t bind to these brain receptors and cause the drop in dopamine that creates nicotine cravings (1). 

Doctors often prescribe Chantix before you stop smoking. The goal is to wean your brain off nicotine, so when you pick a date to quit, you don’t experience uncomfortable side effects. 

Is Chantix Still on the Market?

Pfizer, the manufacturer of Chantix, issued a voluntary recall of the drug in July 2021 (2). The drug was never removed from the market, but the recall has caused a shortage, particularly in the United States.

Why Was Chantix Recalled?

In July 2021, the Food and Drug Administration (FDA) published an alert that some batches of Chantix may contain N-nitroso-varenicline (2). This is a nitrosamine impurity that, with long-term use, can potentially increase the risk of cancer. 

However, the FDA stated that the risk of developing cancer from the compound was less than the risk of long-term tobacco cigarette smoking. 

In May 2022, the FDA released another statement that Chantix containing up to 37 nanograms of N-nitroso-varenicline in a daily dose was safe. 

Ingesting that amount of the compound for the short-term treatment plan that Chantix is used for is not believed to increase your risk of developing cancer.

Does Chantix Cause Cancer?

Chantix contains the nitrosamine compound N-nitroso-varenicline. Nitrosamines have been linked to increased cancer risk in animals and humans (3).

Nitrosamines are present all over the environment. They can even be found in low levels in common foods and beverages, like cured meats, baked goods, and some fruit juices  (4).

However, the FDA believes this is only a concern if you consume large amounts of the compound over a long period of time. 

Chantix contains up to 37 nanograms of N-nitroso-varenicline in a daily dose, which should be safe if used for a short time. The risk of developing cancer from Chantix is still less than the risk of developing cancer from long-term smoking (2).

Other Side Effects of Chantix

Chantix may cause several side effects (5). These include:

- Nausea

- Vivid dreams

- Upset stomach

- Headaches

- Insomnia

- Disturbed sleep

- Sleepwalking

- Drowsiness

- Constipation

- Agitation

A small percentage of people using Chantix have reported depression, anxiety, and suicidal ideation while taking this drug. In one study sponsored by the FDA with 14,131 Chantix users, 16 people, which is 0.11%, were hospitalized for these types of psychiatric symptoms (6).  

If you develop changes in your mood, stop taking the drug and call your doctor.

Also call your doctor right away if you develop: 

- Itching

- Redness

- Swelling

- Hives

These could be signs of an allergic reaction to the drug. 

How Do You Stop Taking Chantix?

Most people take Chantix for about 12 weeks. Your doctor will likely start you on 0.5 milligrams (mg) once a day for the first three days of your treatment. 

On the fourth day, your dose will likely be bumped up to 0.5 mg twice a day. On day eight until the end of your treatment plan, you will likely take 1 mg twice a day. 

You and your doctor will discuss when to stop smoking cigarettes and when to stop taking Chantix. You should be able to stop taking the drug after your treatment plan without needing to taper  (7).  

Is There a Replacement for Chantix?

The Food and Drug Administration (FDA) approved the first generic version of Chantix (varenicline) on August 11, 2021 (8). Par Pharmaceuticals began shipping the generic version of Chantix on September 22, 2021 (9).

In addition to Chantix or its generic alternative, the FDA has only approved one other drug for nicotine-free smoking cessation: ​​Zyban (bupropion hydrochloride).  Zyban is an antidepressant. Researchers aren’t sure how it helps stop nicotine dependence (10).

Is Chantix Still on the Market?

Pfizer, the manufacturer of Chantix, issued a voluntary recall of the drug in July 2021 (2). The drug was never removed from the market, but the recall has caused a shortage, particularly in the United States.

Why Was Chantix Recalled?

In July 2021, the Food and Drug Administration (FDA) published an alert that some batches of Chantix may contain N-nitroso-varenicline (2). This is a nitrosamine impurity that, with long-term use, can potentially increase the risk of cancer. 

However, the FDA stated that the risk of developing cancer from the compound was less than the risk of long-term tobacco cigarette smoking. 

In May 2022, the FDA released another statement that Chantix containing up to 37 nanograms of N-nitroso-varenicline in a daily dose was safe. 

Ingesting that amount of the compound for the short-term treatment plan that Chantix is used for is not believed to increase your risk of developing cancer.

FAQs about Chantix

Is all Chantix recalled?

Chantix was voluntarily recalled by Pfizer, the drug’s manufacturer, for the presence of nitrosamine. This is a compound that can potentially increase the risk of cancer when taken at high levels for a long time. In May 2022, the FDA issued an update to their guidance regarding nitrosamine in varenicline, indicating the FDA is now “confident in manufacturers’ ability to supply patients with varenicline containing the N-nitroso-varenicline impurity at or below the agency’s acceptable intake limit of 37 ng per day.” (11).

Is Chantix available now?

Chantix was never removed from the market. However, the recall did affect the supply of the drug in the United States. This may make it difficult to get, although the generic version of Chantix (varenicline) is now available as well.

Is Chantix FDA approved?

The FDA has approved the use of Chantix that doesn’t contain more than 37 nanograms of N-nitroso-varenicline in a daily dose. 

Is Chantix a controlled substance?

There is no evidence that Chantix can be misused or cause addiction. It is not a controlled substance (12).

What kind of cancer does Chantix cause?

The nitrosamines found in Chantix have been linked to a higher risk of cancer in the liver and kidneys (13).

How long does Chantix stay in your body?

The half life (or time it takes your body to eliminate half of a substance) is 24 hours. Your body should have no trace of the drug after four days (14).

About The Author

Emily is a writer and editor based in Seattle. 

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