Baclofen Side Effects

Medically reviewed by Drugs.com. Last updated on Sep 30, 2024.

Applies to baclofen: intrathecal solution.

Other dosage forms:

• oral packet, oral solution, oral suspension, oral tablet

Precautions

Your doctor should check your progress at regular visits, especially during the first few weeks of treatment with this medicine. During this time, the amount of medicine you are using may have to be changed often to meet your individual needs.

Make sure to keep all appointments to refill the pump. If the pump is not refilled on time, you may experience return of your muscle tightness and early withdrawal symptoms which might include:

• itching of the skin
• decreased blood pressure
  • blurred vision
  • confusion
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
  • sweating
  • unusual tiredness or weakness
• burning, crawling, itching, numbness, prickling, "pins and needles" , or tingling feelings
• seizures

Intrathecal baclofen will add to the effects of alcohol and other CNS depressants (medicines that may make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; other muscle relaxants; and anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using intrathecal baclofen.

Intrathecal baclofen may cause dizziness, drowsiness, false sense of well-being, lightheadedness, vision problems, or clumsiness or unsteadiness in some people. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert, well-coordinated, and able to see well.

Intrathecal baclofen may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if dry mouth continues for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Dizziness, lightheadedness, or fainting may occur when you get up suddenly from a lying or sitting position. Getting up slowly may help lessen this problem.

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 as soon as possible if any of the following side effects occur while taking baclofen:

Symptoms of overdose

• convulsions (seizures)
• dizziness, drowsiness, or lightheadedness
• increased watering of the mouth
• mental confusion
• muscle weakness
• nausea and/or vomiting
• shortness of breath or troubled breathing

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:

After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, Check with your doctor immediately if you notice the following side effects:

• convulsions (seizures)
• facial flushing, headache, increased sweating, or slow heartbeat
• increased muscle spasms
• seeing, hearing, or feeling things that are not there

See also:

For healthcare professionals

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

Cardiovascular adverse events

• 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^[Ref]

Dermatologic

• 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^[Ref]

Endocrine

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

Gastrointestinal

• 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^[Ref]

Genitourinary

• 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^[Ref]

Hematologic

• Frequency not reported: Leukocytosis, petechial rash^[Ref]

Hepatic

• Rare (less than 0.1%): Disorders of hepatic function (e.g., increased AST)^[Ref]

Immunologic

• Common (1% to 10%): Pneumonia
• Uncommon (0.1% to 1%): Septicemia^[Ref]

Metabolic

• Common (1% to 10%): Decreased appetite
• Frequency not reported: Blood glucose increased^[Ref]

Musculoskeletal

• 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^[Ref]

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)^[Ref]

Other

• 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]

Ocular

• Common (1% to 10%): Nystagmus, visual impairment, accommodation disorder, blurred vision, double vision, amblyopia^[Ref]

Psychiatric

• 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^[Ref]

Renal

• Very rare (less than 0.01%): Kidney calculus^[Ref]

Respiratory

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

Further information

Baclofen side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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