Baclofen

(back-lo-fen)

Trade/other name(s): Lioresal, Gablofen

Why would this drug be used?

Baclofen is sometimes used along with opioids (morphine and drugs like it) and other pain medicines for long-term, severe cancer pain that involves muscle spasms.

How does this drug work?

Baclofen relaxes the muscles and belongs to the group of drugs called anti-spasmodics. It helps block reflexes at the spine, although its exact action is not fully known.

Before taking this medicine

Tell your doctor…

• If you are allergic to anything, including medicines, dyes, additives, or foods.
• If you have any medical conditions such as kidney disease, liver disease (including hepatitis), infections, or ulcers. These conditions may require that your medicine dose, regimen, or timing be changed.
• If you have had a stroke, Parkinson's disease, spinal cord injury, or mental or emotional illness. These problems may be worsened by baclofen.
• If you have diabetes. This drug may make your blood sugar go higher.
• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of harm to the fetus if a woman takes this drug during pregnancy, especially later in pregnancy.
• If you are breast-feeding. The drug passes into breast milk, and can affect the baby.
• About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Medicines that slow down the brain or nervous system, such as opioid pain relievers, tranquilizers, sedatives, sleeping pills, antidepressants, other muscle relaxers, antihistamines, anesthetics, and alcohol can worsen side effects, including slowed breathing, low blood pressure, extreme sleepiness, coma, or other serious problems if taken with baclofen.

Check with your doctor, nurse, or pharmacist about whether other medicines, vitamins, herbs, and supplements can cause problems with this medicine.

Interactions with foods

Alcohol can worsen the drowsiness and other side effects of baclofen. Otherwise, no serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Baclofen comes as a pill or as an injection that is given into the fluid around the spine. When one of the pill forms is used, it is usually taken 3 times a day on a regular schedule. Often the doctor will start with a low dose and increase it over time. It can take several weeks for the drug to take full effect.

When stopping the drug, it is important to lower the dose slowly over time, instead of stopping it all at once. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you.

The injectable form of baclofen is used with a pump that slowly injects the drug through a catheter (thin tube) that is inserted in your back, into the fluid around the spine. This is called intrathecal injection.

Keep the medicine in a tightly closed container away from heat and moisture, and out of the reach of children and pets.

Precautions

This medicine can cause drowsiness and lightheadedness. Do not drive, operate machinery, or perform other activities that require alertness until you know how you react to this medicine.

Baclofen can make you feel dizzy or faint, and increase your risk of falling. Be careful getting up, changing position, or walking. Start slowly and hold onto something or someone to hold you steady. Have another responsible adult with you until you know how the medicine will affect you and that you can take care of yourself.

Since baclofen affects the nervous system, it is important not to take other drugs or substances that slow down the brain or nervous system such as alcohol, sedatives, muscle relaxers, and sleeping medicines unless your doctor tells you to do so.

If you have an allergic reaction, with symptoms like trouble breathing, itchy welts on your skin, or swelling in your mouth or throat, get emergency help right away.

Tell your doctor or nurse right away if you have trouble passing your urine, trouble walking, confusion, hallucinations (seeing things that aren't there) or other problems.

If you are having any kind of surgery or medical procedure, be sure to tell the doctor or dentist in charge that you are using this medicine.

If you are using baclofen along with other medicines for chronic cancer pain, talk to your doctor or nurse about taking your pain medicines on a regular schedule to keep it from worsening. If you wait until the pain is bad, it takes more medicine to get it under control. If pain comes back between doses, talk to your cancer team about changing your medicine or adding an extra one for "breakthrough" pain.

Most cancer pain can be controlled. Keep your doctor or nurse informed about how well your pain medicines are working and any side effects you are having. Your cancer team may need to adjust your medicines several times before they find the medicines that work best for you.

Don't stop this medicine or change the dose without talking to your doctor. Baclofen is usually stopped gradually to avoid withdrawal symptoms such as itching, low blood pressure, dizziness, confusion, hallucinations, faintness, sweating, seizures, and feelings of pricking, tingling, itching, burning, or crawling.

If you are using a pump to take baclofen in your back (around your spine), always call the doctor if you think the pump is not working or you aren't getting the medicine. Sudden stopping of the drug going around the spine can cause "rebound" spasms, high fever, and rigid muscles that can cause permanent organ damage, or rarely even death.

If you think you or someone else may have taken an overdose of baclofen, get emergency help right away. Symptoms of overdose may include vomiting, muscle weakness, extreme drowsiness, trouble with vision, fainting, coma, slow or irregular breathing, or seizures. On rare occasions, overdose has resulted from problems in refilling the pump, when the medicine is injected under the skin or into the catheter access port rather than into the pump’s refillable reservoir.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Common

• drowsiness*
• dizziness*
• weakness

Less common

• fatigue
• nausea, vomiting
• upset stomach
• confusion*

Rare

• ovarian cysts (with long term use; usually disappear when drug stopped)
• headache
• trouble sleeping
• constipation
• frequent urination, trouble passing urine, or incontinence
• clumsiness
• hallucinations (seeing or hearing things that aren't there)*
• trembling
• unsteadiness and trouble walking*
• slow or shallow breathing*
• withdrawal symptoms if drug is stopped suddenly*
• allergic reaction*
• death from overdose or sudden withdrawal

*See "Precautions" section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984 (FDA cannot verify dates of drugs approved before 1984).

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.