Reviewed by: HU Medical Review Board | Last reviewed: April 2023

Baclofen is a skeletal muscle relaxant used to treat muscle symptoms caused by multiple sclerosis (MS), including spasm, pain, and stiffness. It is classified as an antispastic agent. It inhibits both monosynaptic (single) and polysynaptic (multiple interwoven) reflexes at the spinal level. Baclofen is indicated for the relief of flexor spasms, clonus (spasms with rhythmic contractions), and muscular rigidity.1

What are the ingredients in baclofen?

The active ingredient in baclofen is baclofen.1

How does baclofen work?

Baclofen inhibits nerve reflex signaling in the spine and other nerve sites to reduce or eliminate spasm. The exact mechanism by which baclofen works to control spasticity is not known.1

Baclofen is often taken by mouth as a tablet or liquid. It is also available as an injection formulated for intrathecal infusion, a method to deliver medication into the spinal fluid by an implantable pump.1

What are the brand names for baclofen?

Baclofen is sold under several different brand names in the US, including but not limited to:

  • Lioresal
  • Lioresal Intrathecal
  • Gablofen

What are the potential side effects of baclofen?

Taking baclofen can cause side effects for some people. The most common ones are:1

  • Drowsiness
  • Dizziness
  • Weakness
  • Fatigue
  • Confusion
  • Headache
  • Insomnia (difficulty sleeping)
  • Low blood pressure
  • Nausea
  • Constipation
  • Urinary frequency
  • Impaired reaction time, some people should be advised to refrain from driving or operating heavy machinery.

Baclofen has a boxed warning, the strictest warning from the US Food and Drug Administration (FDA). It has this warning because if you stop taking baclofen abruptly, there is a risk of serious side effects including hallucination, seizures, and even death. When stopping baclofen, work with your doctor to gradually reduce the dose.1

These are not all the possible side effects of baclofen. Talk to your doctor about what to expect when taking baclofen. You also should call your doctor if you have any changes that concern you when taking baclofen.

Other things to know about baclofen

Baclofen should be used with caution in people with MS who:1

  • Have impaired kidney function
  • Have had a stroke
  • Are children under the age of 12
  • Are pregnant, unless the benefit clearly outweighs potential risk to the fetus
  • Use alcohol and other CNS depressants as the effects may be compounded

Before beginning treatment for MS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of baclofen.

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