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Home / Stop Smoking / Champix side effects

Champix side effects

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  • High success rates
  • Limits withdrawal cravings
  • Hassle-free tablets

As many as two-thirds of smokers in the UK want to quit. Prescription medications like Champix (Varenicline) can triple your chance of quitting successfully. Champix (Varenicline) reduces cravings and nicotine withdrawal symptoms by blocking the nicotine receptors in your brain making smoking less pleasurable and by triggering the release of dopamine.

It's one of only two nicotine-free medications for quitting smoking that is FDA approved, which means the cigarettes aren't replaced with something else.

Champix is taken for an initial course of 12 weeks. This can be extended for a further 12 weeks, to further reduce the risk of a relapse. But, as with any medication, it's important to understand how it works, its advantages and its potential side effects.

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Known side effects

The following are the known side effects associated with taking varenicline (Champix) based on data from drug trials of approximately 5,000 patients, according to the electronic Medicines Compendium (eMC). They are classified in the table below as:

  • Very common – affecting more than 1 in 10 users
  • Common – affecting between 1 in 10 and 1 in 100 users
  • Uncommon – affecting between 1 in 100 and 1 in 1,000 users
  • Rare – affecting between 1 in 1,000 and 1 in 10,000 users
Common side effects Uncommon side effects Rare side effects
  • Common cold
  • Abnormal dreams
  • Insomnia
  • Headache
  • Nausea
  • Bronchitis
  • Sinusitis
  • Increase or decrease of appetite
  • Rash
  • Pruritus (Itching)
  • Joint pain
  • Muscle pain
  • Fatigue
  • Fungal infection
  • Viral infection
  • Panic attacks
  • Abnormal thoughts
  • Restlessness
  • Mood swings
  • Depression and anxiety
  • Hallucinations
  • Sensitivity to touch (hypoaesthesia)
  • Tinnitus (ringing in ears)
  • Angina pectoris (chest pain)
  • Tachycardia, palpitations or increased heart rate
  • Increased blood pressure
  • Hot flushes
  • Respiratory tract inflammation or congestion
  • Dysphonia or throat infection
  • Sinus congestions and hay fever
  • Haematochezia (blood in stool) or change in bowel habits
  • Gastritis
  • Eructation (burping)
  • Mouth ulcers or gingival pain
  • Frequent urination during day or night
  • Influenza symptoms
  • Abnormal liver function
  • Decrease in platelet count
  • Excessive thirst (Polydipsia)
  • Dysphoria
  • Stroke or cerebrovascular accident
  • Increased tonicity (hypertonia)
  • Reduced taste (hypogeusia)
  • Circadian rhythm sleep disorder
  • Partial vision loss (scotoma)
  • Sclera discolouration at side of pupils
  • Mydriasis (dilation of pupil)
  • Photophobia or light sensitivity
  • Myopia or short sightedness
  • Atrial fibrillation or ECG changes
  • Laryngeal pain
  • Snoring
  • Haematemesis (vomiting of blood)
  • Abnormal faeces
  • Coated tongue
  • Joint stiffness
  • Chest inflammation (costochondritis)
  • Increased volume of urine (polyuria) of sugar in urine (glycosuria)
  • Vaginal discharge
  • Sexual dysfunction
  • Abnormal semen analysis
  • Increase in C-reactive protein
  • Decrease in blood calcium

Other side effects and risks

here have been reports of other rare side effects and risks with Champix. The level of these or exact links are not yet fully known.

Champix and mental health

There also may be a connection between Champix and other mental health conditions – with potential side effects of depression, hostility or suicidal thoughts and behaviours. There have been a number of studies carried out, but results have varied. One study found that the likelihood of Champix being linked to suicidal thoughts and depression was eight times higher than that of nicotine replacement products. Other studies found statistically significant link or increased risk from the drug.

While Champix is a highly effective treatment, the FDA did request that it include a black box warning in 2009, to warn of this potential link. Pfizer, the manufacturer of Champix, are conducting their own large scale study to look at the link, and their more definitive results are expected to be available in 2017.

Champix and heart problems

A study of 700 smokers with existing cardiovascular disease looked at the results of treating patients with Champix versus a placebo. They found a slight increase in the number of people who experienced heart attacks for those treated with Champix over a placebo. Whilst these results were not statistically significant and could be random, the FDA posted a warning in 2011 to notify people that there was a chance of increasing their likelihood of cardiovascular complications.

How to prevent the risk of side effects

Overall, your chance of experiencing serious side effects from taking Champix is low. Across 17 studies, only 3.2% of participants taking Champix reported developing any serious health problems, compared with 2.4% of participants not taking it.

However, if you have certain other risk factors, Champix may not suitable for you. It's not advised to take Champix if you've ever suffered from:

  • Depression or mental health conditions
  • Kidney disease
  • Heart disease or circulation problems
  • Heavy alcohol use

Dealing with Champix side effects

Nausea is the most common side effect you are likely to experience. It affects 3 in 10 people taking Champix but this can be eased by taking your tablet with food or by speaking to your doctor about decreasing your dosage.

It's recommended that if you experience any change in mood or behaviour while taking Champix, you should stop taking it immediately as a precaution and should contact your doctor. If you experience any other signs of serious side effects or have any symptoms that are concerning you, you are advised to speak to your doctor or pharmacist.