Can You Smoke While Taking Chantix? The Week-One Rule

If you have just started varenicline, or you are about to, you may be wondering whether it is a problem that you are still smoking. Can you smoke while taking Chantix? In the first week, yes: that is how the medicine is designed to be started. The US label tells patients to begin dosing one week before their quit date, so for that first stretch you are expected to still be smoking. What matters is what happens next.

The short answer: yes in week one, by design

Varenicline (sold as Chantix in the US, Champix elsewhere, and as generics) is different from nicotine patches and gum. You do not start it on your quit day. You start it first, and the quit day comes later. The label and the NHS both build the plan this way, so the medicine is already in your system when the quit day arrives.

That means the first week is a run-in, not a test of willpower. You can keep smoking while you take your first tablets, and you will be told to set a quit date that falls after that run-in. If you are reading this because you are in that first week and feeling guilty about the cigarettes, you can relax: the instructions assume you are still smoking.

Varenicline is a prescription medicine, and this article is a general guide to the label and to NHS advice, not a treatment plan. Your prescriber decides your dose and schedule. If you are unsure about the wording on your own prescription or leaflet, ask the pharmacist or prescriber. For questions about availability, our guide on whether Chantix is still available and what generic varenicline is covers the brand and generic picture.

How the label sets your quit date

The US prescribing information for Chantix on DailyMed says: “Begin CHANTIX dosing one week before the date set by the patient to stop smoking. Alternatively, the patient can begin CHANTIX dosing and then quit smoking between days 8 and 35 of treatment.”

The label describes the first week of dosing as “0.5 mg once daily on days 1-3 and 0.5 mg twice daily on days 4-7,” followed by “1 mg twice daily for a total of 12 weeks.” It also says that “an additional 12 weeks of treatment is recommended for successful quitters to increase likelihood of long-term abstinence.” Those numbers come from the label and are shown here for explanation only; your prescriber decides your own schedule.

The NHS gives similar guidance for the UK. Its page on how and when to take varenicline says to “take your tablets 1 to 2 weeks before your stop smoking date,” that “if you cannot set a date to quit within 2 weeks, you can choose your own target date” which “should be within 5 weeks of starting your treatment,” and that “a course of varenicline lasts for 12 weeks.”

The wording differs a little between the US label (one week before) and the NHS (1 to 2 weeks before), so follow the instructions you were given. What both agree on is the shape of the plan: start the tablets, still smoke for a short while, then stop on a planned date.

Why cigarettes start to feel less rewarding

The label explains the mechanism. Varenicline “binds with high affinity and selectivity at α4β2 neuronal nicotinic acetylcholine receptors,” the same receptors nicotine acts on. In the label’s words, it “stimulates receptor-mediated activity, but at a significantly lower level than nicotine,” while also preventing nicotine from binding there.

The key sentence is this one: “Varenicline blocks the ability of nicotine to activate α4β2 receptors and thus to stimulate the central nervous mesolimbic dopamine system, believed to be the neuronal mechanism underlying reinforcement and reward experienced upon smoking.”

In plain language, the medicine does two jobs at once. It gives a small, steady signal at the receptor, which is why many people find withdrawal easier. And it makes it harder for the nicotine in a cigarette to deliver its usual reward, which is why smoking during the run-in can feel flatter than it used to. The label does not put a number on how much less satisfying cigarettes become, and neither will we. The experience varies from person to person.

Three ways to schedule the course

The label describes more than one way to run the first weeks. Which one fits depends on how ready you are to stop, and your prescriber will choose with you.

The gradual route is for “patients who are sure that they are not able or willing to quit abruptly,” according to the label. A randomized trial published in JAMA in 2015 tested it in 1,510 smokers who were not willing or able to quit within a month but would reduce and then quit within three months. Continuous abstinence during weeks 15 to 24 was 32.1% with varenicline versus 6.9% with placebo, and 27.0% versus 9.9% during weeks 21 to 52 (Ebbert and colleagues, 2015).

What if you are still smoking after week two

If you are following the fixed-date plan and your quit date has arrived, the aim is to stop. If you are on the flexible plan, you have until about day 35. The NHS says that if you cannot set a date within two weeks, you can choose your own target date, which “should be within 5 weeks of starting your treatment.”

If you are past those windows and still smoking the same amount, that is worth telling your prescriber or stop-smoking adviser rather than quietly continuing or quietly stopping the tablets. They can look at whether the plan needs to change, whether the gradual route would suit you better, or whether something else is getting in the way, such as stress, alcohol or a household where everyone smokes.

There is no moral failure in this. The NHS also notes that you should continue the course “even if you have stopped smoking,” because finishing it is part of what increases your chances. Start with a conversation, not a verdict.

Smoking after your quit date: slip, not failure

Many people have a cigarette or two after their quit date. It is common, and the label expects it. It tells prescribers to “encourage patients to continue to attempt to quit if they have early lapses after quit day.” It also says that “another attempt at treatment is recommended for those who fail to stop smoking or relapse when factors contributing to the failed attempt have been addressed.”

In practice, treat a slip as information. What was the trigger? Where were you, who were you with, and what were you feeling? Write it down, adjust the plan for that situation, and carry on with the course. A slip is data, not defeat. If you want more on what typically happens to your body and cravings as the days pass, read what happens to your body when you stop smoking.

Here is a short clip from the CDC with general instructions on how to use varenicline. Your own prescription instructions come first.

Side effects and other medicines that change when you stop

Two things can shift once you stop smoking, and the label calls out both. First, side effects. The label tells patients that “nausea and insomnia are side effects of CHANTIX and are usually transient,” and that if they are persistently troubling, you should tell the prescriber so a dose reduction can be considered. Our guide to varenicline side effects and how long you take it goes through them in more detail.

Second, other medicines. The label states that “pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) may be altered, necessitating dose adjustment” after quitting smoking, with or without varenicline. If you take any of these or similar medicines, mention it when you plan your quit date so your prescriber can monitor you.

The label also lists mood changes, including depression, anxiety and suicidal thoughts, as events reported by some people who tried to quit smoking while taking varenicline, and says to “discontinue CHANTIX and contact a healthcare professional if they experience such symptoms.” Quitting smoking, with or without varenicline, can also bring withdrawal symptoms such as low mood or agitation. If your mood changes in a way that worries you or the people around you, get medical advice promptly. On alcohol, see can you drink alcohol on Chantix and varenicline.

Combining with nicotine replacement

Many people ask whether they can add patches or gum. The label is cautious: “Safety and efficacy in combination with other smoking-cessation therapies has not been established.” In one study cited in it, “coadministration of varenicline and transdermal nicotine resulted in a high rate of discontinuation due to adverse events.” Eight of twenty-two patients (36%) on the combination stopped early because of adverse events, compared with one of seventeen (6%) on the patch plus placebo, and nausea, headache, vomiting, dizziness, dyspepsia and fatigue were more common with the combination.

That does not mean nobody should ever combine them. It means this is a decision for your prescriber, not something to improvise at the pharmacy counter. If you are weighing options, our comparison of the best NRT options explains each product, and you can bring it to the appointment.

Tracking week one alongside your prescription

A medicine handles the chemistry, but the habit part is still yours. iQuit does not prescribe or replace medical advice, but it can sit alongside a varenicline course: watch your smoke-free days add up on the dashboard, then log each craving with its trigger and intensity so you can see how things change through the first weeks. Our guide on using a quit smoking app with Chantix or varenicline shows how to combine the two.

Frequently Asked Questions