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Champix Side Effects

Generic name: varenicline

Medically reviewed by Last updated on Apr 23, 2022.

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 Champix.

For the Consumer

Applies to varenicline: oral tablet

Other dosage forms:

Side effects requiring immediate medical attention

Along with its needed effects, varenicline (the active ingredient contained in Champix) 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

  • Anxiety
  • black, tarry stools
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bloody stools
  • blurred vision
  • burning feeling in the chest or stomach
  • chest pain or discomfort
  • chills
  • cold hands and feet
  • cold sweats
  • confusion
  • cool, pale skin cough
  • deep or fast breathing with dizziness
  • difficult or labored breathing
  • dizziness
  • dry mouth
  • fainting
  • fast, pounding, or irregular heartbeat or pulse
  • flushed, dry skin
  • fruit-like breath odor
  • headache
  • headache, severe and throbbing
  • increased hunger
  • increased thirst
  • increased urination
  • indigestion
  • loss of consciousness
  • nausea
  • nervousness
  • nightmares
  • noisy breathing
  • nosebleed
  • numbness of the feet, hands and around the mouth
  • pain or discomfort in the arms, jaw, back, or neck
  • pale skin
  • pounding in the ears
  • rapid weight gain
  • seizures
  • shakiness
  • slow heartbeat
  • slurred speech
  • stomach pain or upset
  • sweating
  • swollen, painful, or tender lymph glands in the neck, armpit, or groin
  • tenderness in the stomach area
  • tightness in the chest
  • tingling of the hands or feet
  • tremor
  • troubled breathing with exertion
  • unexplained weight loss
  • unusual bleeding or bruising
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • unusual weight gain or loss
  • vomiting
  • vomiting of blood or material that looks like coffee grounds


  • Agitation
  • bleeding gums
  • bloating
  • blood in the urine or stools
  • constipation
  • dark urine
  • decrease in height
  • decreased awareness or responsiveness
  • difficulty in swallowing
  • eye pain
  • feeling of fullness
  • fever
  • frequent urination
  • general feeling of illness
  • heartburn
  • hostility
  • increased sensitivity of the skin to sunlight
  • increased volume of pale, dilute urine
  • irritability
  • itching, skin rash
  • loss of appetite
  • mood changes
  • muscle pain, cramps, or twitching
  • numbness or tingling in the hands, feet, or lips
  • pain or burning in the throat
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • pinpoint red spots on the skin
  • red, scaling, or crusted skin
  • redness or other discoloration of the skin
  • severe sleepiness
  • severe stomach pain
  • severe sunburn
  • sores, ulcers, or white spots on the lips, tongue, or inside the mouth
  • tenderness, pain, swelling, warmth, skin discoloration, and prominent superficial veins over the affected area
  • uncontrolled eye movements
  • yellow eyes or skin

Incidence not known

  • Anger
  • anxiety
  • behavior changes
  • discouragement
  • feeling sad or empty
  • feelings of panic
  • irregular heartbeat
  • loss of interest or pleasure
  • mood swings
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • sleepwalking
  • thoughts of killing oneself

Side effects not requiring immediate medical attention

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
  • absence of menstruation
  • change in taste
  • diarrhea
  • difficulty having a bowel movement
  • difficulty in moving
  • excess air or gas in the stomach or bowels
  • joint pain or swelling
  • lack or loss of strength
  • loss of taste
  • muscle stiffness
  • painful menstruation
  • passing gas
  • toothache
  • trouble sleeping

Less common

  • Belching
  • body aches or pain
  • burning, dry, or itching eyes
  • continuing ringing or buzzing or other unexplained noise in the ears
  • decreased interest in sexual intercourse
  • discharge, excessive tearing
  • ear congestion
  • feeling of constant movement of self or surroundings
  • feeling of warmth
  • hearing loss
  • inability to have or keep an erection
  • increased appetite
  • increased urge to urinate during the night
  • loss in sexual ability, desire, drive, or performance
  • loss of voice
  • nightmares
  • redness in the joints
  • redness of the face, neck, arms and occasionally, upper chest
  • redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
  • sensation of spinning
  • sleepiness or unusual drowsiness
  • sneezing
  • sore throat
  • stomach discomfort
  • stuffy or runny nose
  • transient, mild, pleasant aromatic odor
  • trouble concentrating
  • waking to urinate at night


  • Change in color vision
  • difficulty seeing at night
  • increased sensitivity of the eyes to sunlight
  • night blindness
  • seeing floating dark spots or material before the eyes

For Healthcare Professionals

Applies to varenicline: nasal spray, oral tablet


The most commonly reported side effects included nausea, headache, insomnia, and abnormal dreams.[Ref]


Very common (10% or more): Insomnia (up to 19%), abnormal dreams (up to 13%), depressed mood disorders and disturbances (up to 11%), irritability (up to 11%)

Common (1% to 10%): Agitation, anxiety, depressed mood, depression, hostility, middle insomnia, nervousness, nightmare, restlessness, sleep disorder, tension

Uncommon (0.1% to 1%): Aggression, dissociation, hallucinations, libido decreased, libido increased, mood swings, panic reaction, suicidal ideation, thinking abnormal

Rare (less than 0.1%): Abnormal behavior, bradyphrenia, disorientation, dysphoria, euphoric mood, psychosis, somnambulism

Frequency not reported: Early morning awakening, initial insomnia, neuropsychiatric adverse events, suicidality

Postmarketing reports: Aggressive behavior, changes in behavior, changes in thinking, delusions, completed suicide, exacerbation of underlying psychiatric illness, homicidal ideation, nicotine withdrawal symptoms, panic, suicide, suicide attempt[Ref]


Very common (10% or more): Nausea (up to 40%), vomiting (up to 11%)

Common (1% to 10%): Abdominal discomfort, abdominal distension, abdominal pain, abdominal pain upper, constipation, diarrhea, dry mouth, dyspepsia, flatulence, gastroenteritis, gastroesophageal reflux disease, toothache

Uncommon (0.1% to 1%): Aphthous stomatitis, change of bowel habit, dysphagia, eructation, gastritis, gastrointestinal hemorrhage, gingival pain, hematochezia, mouth ulceration

Rare (less than 0.1%): Abnormal feces, acute pancreatitis, enterocolitis, esophagitis, gallbladder disorder, gastric ulcer, hematemesis, intestinal obstruction, tongue coated[Ref]

Nervous system

Very common (10% or more): Headache (up to 19%)

Common (1% to 10%): Disturbance in attention, dizziness, dysgeusia, lethargy, somnolence

Uncommon (0.1% to 1%): Amnesia, convulsion, hypoesthesia, hypogeusia, migraine, parosmia, seizure, syncope, tremor, vertigo

Rare (less than 0.1%): Balance disorder, cerebrovascular accident, coordination abnormal, circadian rhythm sleep disorder, dysarthria, hypertonia, mental impairment, multiple sclerosis, nystagmus, psychomotor hyperactivity, psychomotor skills impaired, restless legs syndrome, scotoma, sensory disturbance, transient ischemic attack, VIIth nerve paralysis, visual field defect

Frequency not reported: Transient loss of consciousness

Postmarketing reports: Blackouts, hemorrhagic cerebrovascular event, ischemic cerebrovascular event, loss of consciousness[Ref]


Very common (10% or more): Nasopharyngitis (up to 11%)

Common (1% to 10%): Bronchitis, cough, dyspnea, oropharyngeal pain, respiratory disorders, rhinorrhea, upper respiratory tract disorder, upper respiratory tract infection

Uncommon (0.1% to 1%): Allergic rhinitis, asthma, dysphonia, epistaxis, respiratory tract congestion, sinus congestion, throat irritation, upper- airway cough syndrome, upper respiratory tract inflammation

Rare (less than 0.1%): Laryngeal pain, pleurisy, pulmonary embolism, snoring[Ref]


Very common (10% or more): Application site pruritus (up to 11%)[Ref]


Common (1% to 10%): Angina pectoris, chest pain, hospitalization for angina pectoris, hypertension, need for coronary revascularization, new diagnosis of peripheral vascular disease (PVD)/admission for a PVD procedure, nonfatal myocardial infarction, peripheral edema

Uncommon (0.1% to 1%): Blood pressure increased, chest discomfort, ECG abnormal, edema, heart rate increased, hospitalization for angina pectoris, hot flush, myocardial infarction, palpitations, tachycardia

Rare (less than 0.1%): Acute coronary syndrome, arrhythmia, atrial fibrillation, bradycardia, cardiac flutter, cor pulmonale, coronary artery disease, electrocardiogram ST segment depression, electrocardiogram T wave amplitude decreased, thrombosis, ventricular extrasystoles

Frequency not reported: Cardiovascular events[Ref]


Common (1% to 10%): Anorexia, decreased appetite, increased appetite, weight increased

Uncommon (0.1% to 1%): Diabetes mellitus, hyperglycemia, hypoglycemia

Rare (less than 0.1%): Blood calcium decreased, C-reactive protein increased, hyperlipidemia, hypokalemia, polydipsia[Ref]


Common (1% to 10%): Arthralgia, back pain, myalgia, pain in extremity

Uncommon (0.1% to 1%): arthritis, muscle cramp, muscle spasms, musculoskeletal chest pain, musculoskeletal pain

Rare (less than 0.1%): costochondritis, joint stiffness, muscle enzyme increased, myositis, osteoporosis[Ref]


Common (1% to 10%): Asthenia, fatigue, malaise

Uncommon (0.1% to 1%): Chills, pyrexia, tinnitus

Rare (less than 0.1%): Cyst, deafness, feeling cold, Meniere's disease

Frequency not reported: Accidental injury, interaction with alcohol[Ref]


Common (1% to 10%): Pruritus, rash

Uncommon (0.1% to 1%): Acne, dry skin, eczema, erythema, hyperhidrosis, night sweats, urticaria

Rare (less than 0.1%): Erythema multiforme, photosensitivity, psoriasis, severe cutaneous reactions, Stevens-Johnson Syndrome

Frequency not reported: Serious skin reactions[Ref]


Common (1% to 10%): Menstrual disorder

Uncommon (0.1% to 1%): Erectile dysfunction, menorrhagia, nocturia, pollakiuria, polyuria, urine abnormality

Rare (less than 0.1%): Glycosuria, semen analysis abnormal, sexual dysfunction, urethral syndrome, urinary retention, vaginal discharge[Ref]


Common (1% to 10%): Influenza

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


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


Uncommon (0.1% to 1%): Conjunctivitis, eye pain, eye irritation, vision blurred, visual disturbance

Rare (less than 0.1%): Blindness transient, cataract subcapsular, dry eye, lacrimation increased, mydriasis, myopia, night blindness, ocular vascular disorder, photophobia, scleral discoloration, vitreous floaters[Ref]


Uncommon (0.1% to 1%): Anemia, lymphadenopathy

Rare (less than 0.1%): Leukocytosis, platelet count decreased, splenomegaly, thrombocytopenia[Ref]


Uncommon (0.1% to 1%): Thyroid gland disorders[Ref]


Rare (less than 0.1%): Acute renal failure, nephrolithiasis, urine analysis abnormal[Ref]


Rare (less than 0.1%): Angioedema

Frequency not reported: Hypersensitivity reactions[Ref]

More about Champix (varenicline)

Patient resources

Other brands
Chantix, Tyrvaya

Professional resources

Related treatment guides


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

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

3. Cerner Multum, Inc. "Australian Product Information." 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.