Varenicline

What is varenicline?

Varenicline is a prescription medicine used to help adults quit smoking. It works by reducing nicotine cravings and easing withdrawal symptoms, making it easier to stop smoking. It is usually prescribed as part of a structured stop smoking programme, which may include behavioural support[1]. 

What is varenicline used for?

Varenicline is used to support smoking cessation in adults. It is typically offered when other methods – such as nicotine patches or gum – have not worked well or are not appropriate[1]. 

How does varenicline work?

Varenicline acts on the brain’s nicotine receptors in two key ways[1]: 

• It partially stimulates nicotine receptors to reduce cravings and withdrawal symptoms 

• It blocks nicotine from attaching to these receptors, making smoking less satisfying if a person smokes while on treatment 

Who can take varenicline?

Varenicline is suitable for most adults, but certain groups should not take it or may need close supervision. Speak to your doctor first if you[1]: 

• Are under 18 years old 

• Are pregnant or breastfeeding 

• Have had an allergic reaction to varenicline 

• Have a history of heart problems 

• Have a history of mental health conditions (consultation required) 

• Have kidney problems (your dose may need adjustment 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

What is the typical dosage of varenicline?

Varenicline comes as 0.5mg and 1mg tablets. The standard course of varenicline lasts 12 weeks. Your doctor may adjust this depending on how you respond. The typical starting schedule is[1]: 

• Days 1-3: 0.5mg once daily 

• Days 4-7: 0.5 mg twice daily 

• Day 8 onwards: 1mg twice daily 

How do you take varenicline?

To get the most benefit from varenicline, follow these instructions[1]: 

• Take each dose with a full glass of water, ideally after eating 

• Swallow tablets whole – do not crush or chew 

• Stick to the schedule, even if you don’t feel immediate effects 

Can you stop taking varenicline?

Yes, but it’s important to speak to your doctor or pharmacist before stopping. Stopping suddenly may reduce its effectiveness or cause withdrawal symptoms. If you experience side effects or don’t think the medicine is working, consult your healthcare provider for advice[1]. 

What do you do if you take too much varenicline?

Taking too much varenicline can cause unwanted effects such as nausea or vomiting, unusual behaviour or confusion. If this happens, contact your GP, call NHS 111, or go to A&E immediately. Bring the medication packaging with you[1]. 

What do you do if you forget to take varenicline?

If you miss a dose, take it as soon as you remember. If it’s nearly time for your next dose, skip the missed one. Do not double up on doses[1]. 

How do I store varenicline?

To store varenicline safely[1]: 

• Keep it in a cool, dry place below 25°C 

• Store in the original packaging 

• Keep out of sight and reach of children 

• Do not use after the expiry date on the box  

What medicines can’t you take with varenicline?

Varenicline is generally safe with most medications, but you should exercise caution if taking[1]: 

• Nicotine replacement therapies (may increase side effects) 

• Certain antidepressants or antipsychotics (you may need closer monitoring) 

• Insulin for diabetes 

• Warfarin for blood clotting 

• Riociguat for high blood pressure in the lungs 

• Erlotnib for cancer 

• Theophylline or aminophylline for breathing problems 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of varenicline?

Like all medicines, varenicline can cause side effects. Common ones include[1]: 

• Heartburn 

• Headache 

• Trouble sleeping or vivid dreams 

• Dry mouth or a bad taste 

• Sore or swollen nose or throat 

• Diarrhoea 

• Dizziness 

Less common but serious side effects may include mood changes, palpitations, depression or suicidal thoughts[1]. 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about varenicline

How long does varenicline take to work? 
You may notice reduced cravings within the first week[1]. 

Can I smoke while taking varenicline? 
Yes – at first. You set a quit date 1 to 2 weeks after starting treatment[1]. 

Is varenicline better than nicotine patches or gum? 
Some studies suggest it can be more effective for certain people[1]. 

Can I drink alcohol while on varenicline? 
Yes but use caution – some users report stronger effects from alcohol[1]. 

Can I take varenicline if I have depression? 
Possibly, but close monitoring by your healthcare team is advised[1]. 

Is it safe during pregnancy? 
It’s not usually recommended – ask your GP or pharmacist about safer alternatives[1]. 

Can I drive while taking varenicline? 
Yes, unless you feel dizzy or drowsy – do not drive if affected[1]. 

What happens after the 12-week course? 
Some people benefit from another 12-week course to prevent relapse[1]. 

For the official NHS guide to varenicline, visit their website.