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Chantix Side Effects

Generic Name: varenicline

Note: This document contains side effect information about varenicline. Some of the dosage forms listed on this page may not apply to the brand name Chantix.

In Summary

Common side effects of Chantix include: insomnia, nausea, and abnormal dreams. Other side effects include: constipation, dyspepsia, sleep disorder, vomiting, and flatulence. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to varenicline: oral tablet

Along with its needed effects, varenicline (the active ingredient contained in Chantix) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking varenicline:

Less common
  • Difficult or labored breathing
  • hyperventilation
  • tightness in the chest
Incidence not known
  • Anger
  • anxiety
  • behavior changes
  • discouragement
  • feeling sad or empty
  • feelings of panic
  • irregular heartbeats
  • irritability
  • loss of interest or pleasure
  • mood swings
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • sleepwalking
  • thoughts of killing oneself

Some side effects of varenicline may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Abnormal dreams
  • bloated or full feeling
  • change in taste
  • difficulty having a bowel movement (stool)
  • dry mouth
  • excess air or gas in the stomach or intestines
  • general feeling of discomfort or illness
  • headache
  • lack or loss of strength
  • loss of taste
  • nausea
  • passing gas
  • stomach pain
  • trouble sleeping
  • unusual tiredness or weakness
Less common
  • Acid or sour stomach
  • belching
  • body aches or pain
  • chills
  • cough
  • decreased appetite
  • dizziness
  • ear congestion
  • fever
  • heartburn
  • increased appetite
  • indigestion
  • itching skin or rash
  • loss of appetite
  • loss of voice
  • nightmares
  • sleepiness or unusual drowsiness
  • sneezing or sore throat
  • stomach discomfort or upset
  • stuffy or runny nose
  • trouble concentrating
  • unusual drowsiness, dullness, or feeling of sluggishness
  • vomiting

For Healthcare Professionals

Applies to varenicline: oral tablet


Very common (10% or more): Nausea (up to 30%)
Common (1% to 10%): Abdominal pain, flatulence, dyspepsia, vomiting, constipation, GI reflux disease, dry mouth, abdominal pain, diarrhea, abdominal distension, toothache, flatulence
Uncommon (0.1% to 1%): Hematochezia, gastritis, change of bowel habit, eructation, aphthous stomatitis, gingival pain, dysphagia, enterocolitis, esophagitis, GI hemorrhage, mouth ulceration
Rare (less than 0.1%): Hematemesis, abnormal feces, tongue coated, gastric ulcer, intestinal obstruction, acute pancreatitis
Frequency not reported: Gall bladder disease[Ref]


Very common (10% or more): Abnormal dreams, insomnia
Common (1% to 10%): Sleep disorder, nightmare
Uncommon (0.1% to 1%): Panic reaction, thinking abnormal, restlessness, mood swings, depression, anxiety, hallucinations, libido increased, libido decreased, irritability, aggression, agitation, disorientation, dissociation
Rare (less than 0.1%): Dysphoria, bradyphrenia, manic episode
Frequency not reported: Suicidal ideation, psychosis, abnormal behavior, somnambulism[Ref]

Nervous system

Very common (10% or more): Headache (up to 19%)
Common (1% to 10%): Somnolence, dizziness, dysgeusia
Uncommon (0.1% to 1%): Seizure, tremor, lethargy, hypoesthesia, amnesia, parosmia, psychomotor hyperactivity, restless legs syndrome, syncope, tremor, balance disorder convulsion, facial palsy
Rare (less than 0.1%): Cerebrovascular accident, hypertonia, dysarthria, coordination abnormal, hypogeusia, circadian rhythm sleep disorder[Ref]


Very common (10% or more): Nasopharyngitis
Common (1% to 10%): Bronchitis, sinusitis, dyspnea, cough
Uncommon (0.1% to 1%): Upper respiratory tract inflammation, respiratory tract congestion, dysphonia, rhinitis allergic, throat irritation, sinus congestion, upper- airway cough syndrome, rhinorrhea, hoarseness, asthma, pleurisy, postnasal drip, epistaxis
Rare (less than 0.1%): Laryngeal pain, snoring[Ref]


Common (1% to 10%): Rash, pruritus
Uncommon (0.1% to 1%): Erythema, acne, hyperhidrosis, night sweats, acne, dermatitis, dry skin, eczema, psoriasis, urticaria, photosensitivity
Frequency not reported: Severe cutaneous reactions, including Stevens Johnson Syndrome and Erythema Multiforme, angioedema[Ref]


Common (1% to 10%): Weight increased, decreased appetite, increased appetite, anorexia
Rare (less than 0.1%): Polydipsia, C-reactive protein increased, blood calcium decreased
Frequency not reported: Diabetes mellitus, hyperglycemia, hyperlipidemia, hyperkalemia, hypoglycemia[Ref]


Uncommon (0.1% to 1%): Anemia, lymphadenopathy, blood calcium decreased
Rare (less than 0.1%): Platelet count decreased, leukocytosis, splenomegaly, thrombocytopenia[Ref]


Common (1% to 10%): Chest pain
Uncommon (0.1% to 1%): Angina pectoris, tachycardia, palpitations, heart rate increased, hypertension, hot flush, chest discomfort, arrhythmia, bradycardia, ventricular extrasystoles
Rare (less than 0.1%): Atrial fibrillation, electrocardiogram ST segment depression, electrocardiogram T wave amplitude decreased, acute coronary syndrome, cardiac flutter, cor pulmonale, coronary artery disease
Frequency not reported: Myocardial infarction, hypotension, peripheral ischemia[Ref]


Uncommon (0.1% to 1%): Thyroid gland disorders, diabetes mellitus
Very rare (less than 0.01%): Pituitary hemorrhage[Ref]


Uncommon (0.1% to 1%): Conjunctivitis, eye pain, dry eye, eye irritation, vision blurred, visual disturbance
Rare (less than 0.1%): Scotoma, scleral discoloration, mydriasis, photophobia, myopia, lacrimation increased, acquired night blindness, blindness transient, cataract subcapsular, ocular vascular disorder, photophobia, vitreous floaters[Ref]


Common (1% to 10%): Seasonal allergy[Ref]


Uncommon (0.1% to 1%): Pollakiuria, nocturia, menorrhagia
Rare (less than 0.1%): Glycosuria, polyuria, vaginal discharge, sexual dysfunction Frequency not reported: Abnormal urine analysis, polyuria, urine abnormality, urinary retention, menstrual disorder, erectile dysfunction[Ref]


Common (1% to 10%): Arthralgia, myalgia, back pain
Uncommon (0.1% to 1%): Muscle spasms, musculoskeletal chest pain, arthritis, osteoporosis
Rare (less than 0.1%): Joint stiffness, costochondritis, asthenia[Ref]


Frequency not reported: Nephrolithiasis, urethral syndrome, acute renal failure[Ref]


Uncommon (0.1% to 1%): Fungal infection, viral infection, influenza like illness[Ref]


Common (1% to 10%): Liver function test abnormal[Ref]


Common (1% to 10%): Fatigue
Uncommon (0.1% to 1%): Tinnitus, pyrexia, asthenia, malaise
Rare (less than 0.1%): Feeling cold, cyst, semen analysis abnormal, deafness, Meniere's disease, thirst[Ref]


1. Cerner Multum, Inc. "Australian Product Information." O 0

2. "Product Information. Chantix (varenicline)." Pfizer U.S. Pharmaceuticals Group, New York, NY.

3. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.