Baclofen vs. Flexeril Side Effects, Strengths, Interactions

• Baclofen (Gablofen, Lioresal) and Flexeril (cyclobenzaprine) are muscle relaxants. Baclofen us used in people with multiple sclerosis to manage symptoms and signs of muscle spacicity and pain. Flexeril is used used for the treatment of short-term relief of skeletal muscle spasms and pain associated with short-term painful muscle and skeletal problems. 
• Baclofen is not approved or recommended for the treatment of skeletal muscle spasms due to rheumatoid diseases, stroke, cerebral palsy, or Parkinson's disease. Flexeril is not approved for the treatment of multiple sclerosis symptoms.
• Side effects of baclofen and Flexeril that are similar include:
  • Drowsiness
  • Dizziness
  • Headache
  • Nausea
  • Constipation
  • Confusion
• Side effects of baclofen that are different and do not occur with Flexeril include:
  • Weakness
  • Seizures
  • Vomiting
  • Low blood pressure (hypotension)
  • Respiratory depression
  • Inability to sleep (insomnia)
  • Increased urinary frequency or urinary retention
• Side effects of Flexeril that are different and do not occur with baclofen include:
  • Dry mouth
  • Fatigue
  • Blurred vision
  • Unpleasant taste
  • Nervousness
  • Acid reflux
  • Abdominal pain or discomfort
• It is not recommended to take baclofen and Flexeril at the same time because when taken together they increase sedation and drowsiness.
• Suddenly stopping oral baclofen may cause seizures and hallucinations. Suddenly stopping Flexeril after prolonged use can lead to symptoms of withdrawal such as headaches, nausea, and weakness.
• Brand names for baclofen include Gablofen and Lioresal.
• The brand name Flexeril has been discontinued in the U.S. Brand names of cyclobenzaprine available in the U.S. are Amrix and Fexmid.

Baclofen is a medication that relaxes skeletal muscles. Chemically, baclofen is related to gamma-aminobutyric acid (GABA), a naturally occurring neurotransmitter in the brain. Neurotransmitters are chemicals that nerves use to communicate with one another. GABA released by some nerves causes the activity of other nerves to decrease. It is thought that baclofen acts like GABA and blocks the activity of nerves within the part of the brain that controls the contraction and relaxation of skeletal muscle.

Flexeril (cyclobenzaprine) is a muscle relaxant. Flexeril is used with rest and physical therapy for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. It is only for short-term use, up to two or three weeks.

Baclofen uses

Baclofen is used for treating spasm of skeletal muscles, muscle clonus, rigidity, and pain caused by disorders such as multiple sclerosis. It is also injected into the spinal cord (intrathecal) for management of severe spasticity.

Flexeril uses

Cyclobenzaprine is used with rest and physical therapy for short-term relief of muscle spasms associated with acute painful muscle and skeletal conditions. It is only for short-term use, up to two or three weeks.

Baclofen side effects

Common side effects of baclofen are:

• Drowsiness
• Weakness
• Dizziness
• Headache
• Seizures
• Nausea
• Vomiting
• Low blood pressure
• Constipation
• Confusion
• Respiratory depression
• Inability to sleep
• Increased urinary frequency or urinary retention

Abrupt discontinuation of oral baclofen may cause seizures and hallucinations. Abrupt discontinuation of intrathecal baclofen may result in:

• High fever
• Rebound spasticity
• Muscle rigidity

Rhabdomyolysis (muscle breakdown) that can progress to failure of several organs, including the kidney, and even death.

Flexeril side effects

The most common side effects of cyclobenzaprine include:

• Drowsiness
• Dry mouth
• Fatigue
• Headaches
• Dizziness

Other reported side effects include:

• Nausea
• Constipation
• Blurred vision,
• Unpleasant taste
• Nervousness
• Confusion
• Acid reflux
• Abdominal pain or discomfort

Possible serious side effects include:

• Seizures
• Abnormal heart beats
• Stroke
• Heart attacks
• Heat stroke

Abruptly stopping Flexeril after prolonged therapy may cause withdrawal symptoms such as headaches, nausea, and weakness.

You should not take Flexeril and baclofen together because it increases sleepiness and sedation.

Baclofen dosage

The usual starting dose of oral baclofen for treating spasticity in adults is 5 mg given three times daily. Based on the response, the dose can be increased by 5 mg every three days to a maximum of 80 mg/day in divided doses.

Flexeril dosage

The recommended dose of cyclobenzaprine dose is 5 or 10 mg three times daily using immediate release tablets or 15 or 30 mg once daily using extended release tablets.

Baclofen drug interactions

• Use of baclofen with other drugs that also depress the function of nerves may lead to additional reduction in brain function.
• In addition to the risk of depressing brain function, the use of baclofen and tricyclic antidepressants (for example, amitriptyline [Elavil, Endep], doxepin [Sinequan, Adapin]) together may cause muscle weakness.
• Use of baclofen and monoamine oxidase inhibitors (for example, phenelzine [Nardil], tranylcypromine or [Parnate]) can result in greater depression of brain function as well as low blood pressure.
• Because baclofen can increase blood sugar, doses of antidiabetic drugs may need to be adjusted when baclofen is started.

Flexeril drug interactions

• Cyclobenzaprine is chemically related to the tricyclic class of antidepressants, for example, amitriptyline (Elavil, Endep), nortriptyline Pamelor). As such, it should not be taken with or within two weeks of any monoamine oxidase (MAO) inhibitor, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane). High fever, convulsions, and even death can occur when these drugs are used together.
• Cyclobenzaprine interacts with other medications and drugs that slow the brain's processes, such as
  • alcohol,
  • barbiturates,
  • benzodiazepines, for example, diazepam (Valium), lorazepam (Ativan), and
  • narcotics.

Baclofen safety

• The use of baclofen by pregnant women has not been evaluated.
• Baclofen can be detected in the breast milk of mothers taking oral baclofen. No information is available on the presence of baclofen in the breast milk of mothers receiving baclofen intrathecally.

Flexeril safety

• There are no adequate studies of cyclobenzaprine in pregnant women. However, studies in animals suggest no important effects on the fetus. Cyclobenzaprine therefore can be used in pregnancy if the physician feels that it is necessary.
• It is not known whether cyclobenzaprine is secreted in milk. However, since it is related to the tricyclic antidepressants, some of which are excreted in breast milk, caution is advised in using this medication in women who are breastfeeding.