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 (e.g., Elavil, Sinequan) together may cause muscle weakness.

Use of Baclofen and monoamine oxidase inhibitors (e.g. Nardil, 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 begun.

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.

Baclofen may cause drowsiness, weakness, dizziness, headache, seizures, nausea, vomiting, low blood pressure, constipation, confusion, respiratory depression, inability to sleep, and 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, and rhabdomyolysis (muscle breakdown) that can progress to failure of several organs, including the kidney, and even death.