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Chantix (varenicline)

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 4 minutes read

Chantix is a medicine containing varenicline – known as a selective nicotine-receptor partial agonist –that can help you in the initial stages of quitting smoking, when you suffer nicotine withdrawal effects and cravings.

To have the best chance of quitting smoking completely, many people use stop smoking services, some of which are free, and some of which provide prescriptions for stop smoking aids, including Chantix. They can also help you find strategies to break the habit of smoking. Together you will set a stop smoking date, and they will help you prepare for that. All the evidence is that you have the best chance of quitting smoking through a combination of psychological support and medication such as Chantix.

How does Chantix work?

Chantix acts on the nicotine receptors in the brain by blocking nicotine from having its effect, breaking the pleasure-reward association of smoking while at the same time reducing cravings and withdrawal symptoms. This all works towards reducing the pleasurable effects of smoking and nicotine. At the same time it allows a tiny amount of dopamine to be released in the brain (the ‘feel good’ chemical that smoking can trigger) and so helps to reduce any craving for a cigarette. This then breaks the cycle of wanting to smoke again, and avoids feelings of depression or irritability that can accompany nicotine cravings, and any difficulty in sleeping.

Doctor’s advice

Treatment schedule

The usual treatment course of Chantix tablets is 12 weeks, starting one week before the date you intend to quit. You can continue to smoke and gradually wean down during this week, and should notice that the cravings for cigarettes reduces each day.

From the quit date onwards, you continue to take the tablets for the remainder of the course.

The starter pack of Chantix contains 25 tablets with doses varying between varenicline 0.5 mg and 1 mg and this is followed by a maintenance pack containing only varenicline 1 mg tablets.

For week 1: The dosage is one 0.5 mg tablet daily for the first 3 days, then increased to one 0.5 mg tablet twice a day (morning and evening) for the remainder of the week.

For weeks 2 to 12: One 1 mg strength tablet is taken twice a day. After completing the course, you will have stopped smoking for at least 11 weeks. The theory is that you will no longer have nicotine cravings or withdrawal symptoms, and you have broken the habit and behavioral cues that keep people smoking.

If you are not able to quit smoking right away, you should reduce smoking during the first 12 weeks of treatment and quit by the end of that treatment period. Discuss with your pharmacist or stop smoking adviser on what to do after this as a 12 week course can be repeated in abstinent individuals to help reduce the risk of any relapse.

Common side effects

Like all medicines, Chantix can cause side effects in some people. Giving up smoking with or without treatment can cause various symptoms, including feeling depressed, irritable, frustrated or anxious, sleeplessness, difficulty concentrating, decreased heart rate and increased appetite or weight gain.

Rarely mental health symptoms can arise, either from Chantix or stopping smoking, including agitation, depression or mood changes, so see your doctor urgently if this occurs.

It can sometimes be difficult to tell whether it’s Chantix or stopping smoking that’s to blame for some symptoms. Chantix often causes inflammation in the nose and throat, abnormal dreams, difficulty sleeping, headaches and nausea but a full list of possible side effects is available in your medicine pack.

Is Chantix for everyone?

It suits most people, but caution should be added if you have a kidney or heart problem, or if you have certain mental health conditions, as your doctor may suggest a more suitable alternative. It makes some people less tolerant of alcohol, so be cautious with alcohol consumption when first starting Chantix, and speak to your doctor if you have alcohol dependency, as there may be a better option for you.

Chantix is not recommended in pregnancy or breastfeeding, as there is too little research to say whether it is safe. However, smoking during pregnancy carries a very significant risk to your baby, so it’s worth choosing this time to quit: nicotine replacement therapy (NRT) is usually a safe option.

Chantix tablets are suitable for adults over 18 years only.

When should I see my doctor or pharmacist?

If any of the common side effects are intolerable or not subsiding after a few weeks, speak to your stop smoking adviser, doctor or pharmacist, and consider together any alternative methods to help you stop smoking. Additionally, any of these professionals may be able to help with a continuation course or alternative if you have relapsed or continue to feel the urge to smoke after your 12-week treatment course.

You should also speak to your doctor urgently if you feel severely agitated, anxious, depressed or have thoughts about hurting yourself.

Seek immediate medical attention for any of the rare but serious adverse effects listed in your product information, such as chest pain, difficulty breathing, mouth or throat swelling, a blistering or peeling skin rash or a suspected seizure.

You should also speak to your doctor urgently if you feel severely agitated, anxious, depressed, or have thoughts about hurting yourself.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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