Baclofen belongs to two groups of medications known as muscle relaxants and antispastics. It is used to treat spasticity (uncontrolled muscle movements) caused by multiple sclerosis, spinal cord injuries, or spinal cord diseases. It is believed to work mainly by relaxing the muscles.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult dose of baclofen varies according to need. It is usually started at doses of 5 mg taken 3 times a day for 3 days, followed by 10 mg taken 3 times a day for 3 days, increasing each dose by 5 mg every 3 days until the best dose is reached. The maximum recommended dose of baclofen is 20 mg 4 times daily.

This medication can be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

This medication should not be stopped suddenly. If you believe it is necessary to stop taking this medication, contact your doctor to discuss the best way for you to stop the medication without causing problems.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take this medication if you are allergic to baclofen or any ingredients of the medication.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal or stomach pain or discomfort
• constipation
• decreased sexual ability
• diarrhea
• dizziness
• drowsiness
• dry mouth
• fatigue
• frequent urination
• headache
• increased perspiration
• low blood pressure (e.g., fainting, dizziness, lightheadedness, blurred vision, nausea)
• nausea
• tiredness
• trouble sleeping
• vomiting
• weakness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• breathing problems
• confusion
• difficulty speaking
• false sense of well-being
• hallucinations (seeing or hearing things that aren't there)
• loss of coordination
• muscle pain
• nightmares or vivid dreams
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of heart problems (e.g., tiredness, swelling in the legs, shortness of breath)
• signs of urinary tract problems (e.g., decreased urine production, difficulty urinating, bloody or dark urine)
• skin rash or hives
• slow heartbeat
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• tingling or numbness of the hands or feet
• trembling
• uncontrolled eye movements
• vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• seizures

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Alcohol and other medications that cause drowsiness: Do not combine baclofen with alcohol or other medications that cause drowsiness (e.g., antidepressants, sleeping pills, anxiety medications). These combinations can cause additional breathing difficulties, drowsiness, sedation, coma, and can be life-threatening.

Drowsiness/reduced alertness: Baclofen may affect the mental or physical abilities needed to drive or operate machinery. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. This occurs because baclofen is primarily removed from the body by the kidneys. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Medical conditions: Certain medical conditions may make it more likely for you to experience serious side effects. People with certain types of bladder problems, stomach ulcers, breathing problems, and seniors with cerebrovascular problems (disorder of the blood vessels supplying the brain) should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Mental health: Baclofen may cause symptoms of psychosis or schizophrenia to get worse for people who have mental health problems. If you experience symptoms such as hallucinations, mania (feeling unusually over-excited or uninhibited), or delusional thinking, or notice them in a family member who is taking this medication, contact your doctor as soon as possible.

Seizures: Baclofen may cause a loss of seizure control, causing seizures to occur more often. If you have a history of epilepsy or medical conditions that increase your risk of seizures, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Withdrawal effects: If baclofen is suddenly stopped after regular use, withdrawal symptoms may occur, including:

• anxiety with racing heart and sweating
• confusion
• hallucinations (seeing and hearing things that aren't there)
• insomnia (difficulty sleeping)
• involuntary movements
• psychotic, manic, or paranoid states
• seizures
• worsening of spasticity (loss of control of muscles)

Except when serious side effects occur, the dose should be reduced slowly when stopping the medication (over a period of approximately 1 to 2 weeks).

Pregnancy: The safe use of baclofen during pregnancy has not been established. Baclofen crosses the placental barrier and may affect the developing baby. Babies born to women who have taken baclofen during pregnancy may experience withdrawal symptoms after birth. If you are or may become pregnant, speak to your doctor. This medication should be taken during pregnancy only when the potential benefits outweigh the possible risks.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking baclofen, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safe use of baclofen by children under the age of 12 years has not been established and is not recommended.

Seniors: People over the age of 65 are more likely to experience side effects of taking baclofen. Doses for seniors should generally be lower and increased more slowly than for other adults.

There may be an interaction between baclofen and any of the following:

• alcohol
• alpha agonists (e.g., clonidine, guanfacine)
• antihistamines (e.g., azelastine, cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• barbiturates (e.g., butalbital, phenobarbital)
• benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
• brimonidine
• buprenorphine
• cannabis
• chloral hydrate
• clonidine
• diphenoxylate
• efavirenz
• entacapone
• esketamine
• general anesthetics (medications used to put people to sleep for surgery)
• guanfacine
• lemborexant
• methadone
• metoclopramide
• mirtazapine
• other muscle relaxants (e.g., cyclobenzaprine, methocarbamol, orphenadrine, tizanidine)
• nabilone
• narcotic pain relievers (e.g., codeine, fentanyl, morphine, oxycodone, tapentadol, tramadol)
• pomalidomide
• pramipexole
• pregabalin
• ropinirole
• rotigotine
• scopolamine
• seizure medications (e.g., clobazam, levetiracetam, primidone, topiramate, valproic acid)
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• sodium oxybate
• tetrabenazine
• thalidomide
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, imipramine)
• zolpidem
• zopiclone

If you are taking any medications containing this drug, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription) and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or illegal drugs can affect the action of many medications, you should let your prescriber know if you use them.