Side Effects


Commonly reported side effects of baclofen include: drowsiness. Other side effects include: asthenia, dizziness, headache, and nausea. Continue reading for a comprehensive list of adverse effects.

Applies to baclofen: oral packet, oral solution, oral suspension, oral tablet. Other dosage forms:

    • intrathecal solution

Serious side effects of Baclofen

Along with its needed effects, baclofen 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 baclofen:

Less common or rare

    • Bloody or dark urine
    • chest pain
    • clumsiness, unsteadiness, trembling, or other problems with muscle control
    • fainting
    • false sense of well-being
    • mental depression or other mood changes
    • pounding heartbeat
    • ringing or buzzing in the ears
    • seeing or hearing things that are not there
    • skin rash or itching
    • slurred speech or other speech problems
    • swelling of the ankles
    • unexplained muscle stiffness
    • unusual excitement

Get emergency help immediately if any of the following symptoms of overdose occur while taking baclofen:

Symptoms of overdose

    • Blurred vision
    • dizziness
    • drowsiness
    • irregular, fast or slow, or shallow breathing
    • lightheadedness
    • loss of strength or energy
    • muscle pain or weakness
    • pale or blue lips, fingernails, or skin
    • seizures
    • sleepiness or unusual drowsiness
    • trouble breathing
    • unusual weak feeling

Other side effects of Baclofen

Some side effects of baclofen 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

    • Confusion
    • constipation
    • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
    • headache
    • increased need to urinate
    • nausea
    • passing urine more often
    • sweating
    • trouble sleeping
    • unusual tiredness or weakness

Less common or rare

    • Diarrhea
    • loss of appetite
    • muscle or joint pain
    • numbness or tingling in the hands or feet
    • stomach pain or discomfort
    • stuffy nose
    • weight gain

For Healthcare Professionals

Applies to baclofen: compounding powder, intrathecal solution, oral granule, oral liquid, oral suspension, oral tablet.


Common (1% to 10%): Cardiac output decreased, hypotension, hypertension, diminished cardiovascular functions, peripheral edema

Rare (less than 0.1%): Arrhythmias, palpitations, chest pain

Frequency not reported: Bradycardia, orthostatic hypotension


Common (1% to 10%): Rash, hyperhidrosis, urticaria/pruritus, facial edema

Uncommon (0.1% to 1%): Alopecia, diaphoresis

Frequency not reported: Rash, sweating, contact dermatitis, skin ulcer


Common (1% to 10%): Ovarian cysts are palpable in 4% of women treated with for up to one year


Very common (10% or more): Nausea (especially at start of therapy) (up to 11%)

Common (1% to 10%): Dry mouth, GI disorder/disturbance, constipation, diarrhea, retching, vomiting, increased salivation

Uncommon (0.1% to 1%): Dysphagia, dehydration, ileus, decreased taste sensation

Rare (less than 0.1%): Colicky abdominal pain, anorexia

Frequency not reported: GI hemorrhage


Very common (10% or more): Urinary retention (up to 12%)

Common (1% to 10%): Urinary incontinence, urination impaired, sexual dysfunction, urinary frequency, enuresis, dysuria

Rare (less than 0.1%): Erectile dysfunction

Frequency not reported: Dysuria, abnormal ejaculation, oliguria, vaginitis


Frequency not reported: Leukocytosis, petechial rash


Rare (less than 0.1%): Disorders of hepatic function (e.g., increased AST)


Common (1% to 10%): Pneumonia

Uncommon (0.1% to 1%): Septicemia


Common (1% to 10%): Decreased appetite

Frequency not reported: Blood glucose increased


Very common (10% or more): Hypotonia (up to 52%), lower extremity weakness (up to 15%), disturbances of gait and balance

Common (1% to 10%): Muscular weakness, myalgia, upper extremity weakness, back pain, muscular hypertonia

Nervous system

Very common (10% or more): Somnolence (up to 28%), drowsiness (up to 18%), headache (up to 16%), seizures (especially on discontinuation of therapy) (up to 15%), sedation, dizziness (up to 12%)

Common (1% to 10%): Fatigue, ataxia, tremor, lightheadedness, lassitude, exhaustion, numbness/itching/tingling, slurred speech, lethargy, hypertonia, paresthesia

Rare (less than 0.1%): Dysarthria, dysgeusia, syncope, dyskinesia, coma, potentially life-threatening withdrawal symptoms (as a result of sudden interruption of drug delivery)


Common (1% to 10%): Tinnitus, pain, asthenia

Uncommon (0.1% to 1%): Accidental injury, weight loss

Very rare (less than 0.01%): Hypothermia

Frequency not reported: Drug withdrawal syndrome

Uncommon (0.1% to 1%): Subdural hemorrhage, accidental injury, weight loss[Ref]


Common (1% to 10%): Nystagmus, visual impairment, accommodation disorder, blurred vision, double vision, amblyopia


Common (1% to 10%): Confusional state, hallucination, depression, insomnia, euphoric mood, nightmare, personality changes

Uncommon (0.1% to 1%): Memory loss/impairment, suicidal ideation, attempted suicide

Rare (less than 0.1%): Excitement


Very rare (less than 0.01%): Kidney calculus


Common (1% to 10%): Respiratory depression, hypoventilation, dyspnea, bradypnea, feeling of pressure in the chest

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