A stop-smoking medicine
Varenicline
A prescription tablet that helps people stop smoking by reducing cravings and the satisfaction from smoking.
What is Varenicline?
Varenicline (Champix) is a prescription tablet used to help people stop smoking. It reduces cravings and withdrawal symptoms and makes smoking less satisfying. It is started while still smoking, with a quit date set in the first one to two weeks, and common side effects include nausea and vivid dreams.
Education and reference only. This is a plain-language guide to Varenicline — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Varenicline, sold as Champix, is a prescription tablet that helps people stop smoking. It is started while you are still smoking, with a quit date usually set in the first week or two, and used alongside stop-smoking support. It is one of the more effective stop-smoking medicines.
How it works
Varenicline acts on the nicotine receptors in the brain. It partly stimulates them, which eases cravings and withdrawal symptoms, while also blocking nicotine from those receptors, so that if you do smoke it is less satisfying. This dual action helps reduce both the urge to smoke and the reward from smoking.
Company & origin
Originated / developed by: Pfizer (originator).
A stop-smoking medicine introduced in the mid-2000s that acts on nicotine receptors.
Practical use
How to take Varenicline
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Start it while you are still smoking, and set your quit date for the first week or two of treatment.
- Take it with food and a full glass of water to reduce the chance of feeling sick.
- Use it alongside stop-smoking support for the best chance of staying smoke-free.
- Report any low mood, agitation or unusual thoughts or behaviour to your prescriber.
- If you miss a dose, take it as soon as you remember unless it is nearly time for the next one, then skip it — do not double up.
Weighing it up
Advantages & disadvantages of Varenicline
Advantages
- One of the most effective medicines for helping people stop smoking.
- Reduces both cravings and the satisfaction you get from smoking.
- Most effective when combined with behavioural stop-smoking support.
Disadvantages
- Nausea is common, especially at first.
- Can cause vivid or unusual dreams and disturbed sleep.
- Mood or behaviour changes have been reported and need watching.
Practical use
Good to know
It is started a week or two before your quit date while still smoking, then continued for around twelve weeks, and works best with behavioural support. Nausea and vivid, unusual dreams are the most common nuisance effects and often settle. Mood and behaviour changes have been reported, so any low mood, agitation or unusual thoughts should be reported promptly. Taking it with food and a full glass of water helps reduce nausea.
Who should not take it / use with caution
- People who have had an allergic reaction to varenicline.
- Used with caution in people with a history of depression or other mental-health conditions, as mood changes can occur.
- Caution and dose adjustment in severe kidney problems, and it is avoided in pregnancy and breastfeeding.
Monitoring
- Mood and behaviour, including any unusual thoughts, especially early in treatment.
- Nausea and sleep effects, and how well you are tolerating it.
- Progress with quitting smoking at follow-up appointments.
Side effects
- Nausea is very common, particularly when starting, and often settles with time.
- Vivid or unusual dreams, difficulty sleeping, headache and a dry mouth can occur.
- Less commonly, low mood, agitation or unusual thoughts and behaviour — report these promptly.
Key interactions
- It has relatively few drug interactions, but stopping smoking itself can change the levels of some medicines (such as certain asthma or mental-health treatments), which may need adjusting.
- Combining it with nicotine replacement may increase side effects such as nausea — check with your prescriber.
- Alcohol may affect you more than usual, so take care, and tell your pharmacist about all your medicines.
Available as: Tablets.
Answers
Varenicline: frequently asked questions
How does varenicline help me stop smoking?
It acts on nicotine receptors in the brain, easing cravings and withdrawal while also making smoking less satisfying if you do light up.
Why does it make me feel sick?
Nausea is the most common side effect, especially early on. Taking it with food and a full glass of water helps, and it usually settles with time.
Do I keep smoking when I start it?
Yes — you start varenicline while still smoking and set a quit date for the first week or two, so the medicine has time to take effect.
Is varenicline the same as Champix?
Yes. Varenicline is the active-ingredient name and Champix is a brand name for the same medicine.
Should I tell anyone if my mood changes?
Yes. Mood and behaviour changes have been reported, so report any low mood, agitation or unusual thoughts to your prescriber promptly.
The wider class
About Smoking-cessation aids
Varenicline belongs to the smoking-cessation aids class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF: Varenicline.
- NICE CKS: Stop smoking treatments.
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