Baclofen, sold under the brand name Lioresal among others, is a medication used to treat muscle spasticity, such as from a spinal cord injury or multiple sclerosis. Baclofen is a potent muscle relaxant and GABA agonist. It may also be used for hiccups and muscle spasms near the end of life, and off-label to treat alcohol use disorder or opioid withdrawal symptoms. It is taken orally or by intrathecal pump (delivered into the spinal canal via an implantable pump device). It is sometimes used transdermally (applied topically to the skin) in combination with gabapentin and clonidine prepared at a compounding pharmacy. It is believed to work by decreasing levels of certain neurotransmitters.
Baclofen should be avoided in the setting of chronic kidney disease and end stage renal disease as even small doses can cause excessive toxicity. Common side effects include sleepiness, weakness, and dizziness. Serious side effects, such as seizures and rhabdomyolysis, may occur if use of baclofen is stopped abruptly. Use during pregnancy is of unclear safety, whilst use during breastfeeding is likely safe, and even more so if oral administration is avoided.