If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Drowsiness, dizziness, or sedation, which may affect your ability to drive or operate machinery or perform other hazardous tasks. The sedative effect of baclofen may be enhanced by alcohol or by other medications that also cause sedation (such as benzodiazepines, opiates).
- Weakness, fatigue, insomnia, nausea, constipation, low blood pressure, headache, and confusion have also been reported.
- Sudden discontinuation of baclofen has been associated with hallucinations and seizures. Baclofen should be withdrawn slowly unless it is an emergency.
- May not be suitable for some people, including those with a history of stroke or who rely on spasticity to maintain an upright position, balance, or for increased function. The dosage of baclofen should be reduced in those with kidney disease.
- People with a history of seizures or epilepsy should be monitored regularly for changes in seizure control or EEG recordings.
- Neonatal withdrawal symptoms, such as increased muscle tone, tremor, jitteriness, or seizures have been reported starting hours to days after delivery in neonates whose mothers were treated with oral baclofen throughout pregnancy. If the potential benefit of using baclofen during pregnancy justifies the potential risk to the fetus then gradually reduce the dose and discontinue baclofen before delivery. Baclofen appears in low levels in milk but is not expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months. Monitor newborn infants for signs of sedation.
- May cause an increase in the risk of ovarian cysts.
Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects.