Cerebral Palsy: Medicines to Relax Spastic Muscles

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Cerebral Palsy: Medicines to Relax Spastic Muscles


Medicines injected into spastic muscles

Generic NameBrand Name
alcohol "washes" 
botulinum toxin, onabotulinumtoxinABotox
phenol "washes" 

Medicines taken by mouth

Generic NameBrand Name

How It Works

These medicines (sometimes called antispasmodics) work in different ways to relax muscles and reduce muscle spasticity and muscle spasms. For example:

  • Baclofen blocks signals between the spinal cord and the muscles.
  • Botulinum toxin paralyzes the spastic muscle.
  • Dantrolene interferes with muscle contraction.
  • Diazepam relaxes the brain and body.

The injectable medicines act only on the nerves and muscles surrounding the area where they are injected. Doctors give the injections directly into the affected muscle. The oral (systemic) forms that you take by mouth travel throughout the body before reaching the affected muscles.

Why It Is Used

These medicines help relax muscles temporarily.

Injectable medicines help relax tight muscles in the legs or arms affected by cerebral palsy. Injectable medicines may be used:

  • When muscle tightness interferes with daily activities, especially walking.
  • To increase the effectiveness of physical therapy.
  • To determine whether nerve surgery is appropriate. Doctors often can predict the potential success of surgery by how nerves and muscles react to the injected medicine.

The doctor may suggest injection of botulinum toxin into the salivary glands to help reduce the severity of drooling.

Oral medicines may be used before physical therapy or at bedtime to help relax tight muscles and stop muscle spasms. Diazepam can help relax muscles after orthopedic surgery.

How Well It Works

These medicines may improve the effectiveness of physical therapy or delay the need for surgery on the muscles, tendons, and joints. If injectable medicines successfully relax the nerves and muscles, surgical cutting of the nerves may also be helpful.

More research is needed to find out the overall usefulness and safety of this type of medicine in helping people who have cerebral palsy.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you or your child has:

  • Trouble breathing, swallowing, or speaking.
  • Swelling of the face, lips, tongue, or throat.
  • Muscle weakness throughout the body.
  • Problems with your sight or voice.
  • Drooping eyelids.
  • Loss of bladder control.

Call your doctor right away if you or your child has:

  • Hives.
  • Signs of skin infection, such as increased pain, redness, swelling, or fever.
  • Lasting swelling or pain at the injection site.
  • Seizures while taking intrathecal baclofen.

Common side effects of this injectable medicine include:

  • Pain as the shot (injection) is given or at the site of the shot.
  • Loss of feeling in the area where the shot was given.
  • Rash.
  • Flu-like symptoms, such as nausea or headache.

Common side effects of this oral medicine include:

  • Feeling dizzy or lightheaded.
  • Feeling drowsy.
  • Feeling weak.
  • Nausea or vomiting.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Your doctor may talk to you about intrathecal baclofen. It's baclofen that's given directly into the fluid surrounding the spinal cord. A small pump is surgically placed under the skin of the abdomen. Medicine is carried through a tube attached to the pump into the fluid surrounding the spinal cord. The pump is programmed to release a continuous amount of medicine. Benefits of giving baclofen this way include:

  • Reduced medicine needs. Because intrathecal baclofen is given right into the spinal fluid, it takes less medicine to be effective than with pills. This reduces side effects such as nausea and drowsiness, which are a problem with the oral form of the medicine.
  • Improved muscle tone and function.

Disadvantages of using baclofen through a pump include the following:

  • The insertion of the pump carries a risk of infection.
  • In rare cases, problems with the pump, such as failure or breakage, result in sudden withdrawal. Symptoms such as itching, rebound spasticity, and rapid heartbeat may be noticed. Other malfunctions can cause an overdose and lead to breathing problems and coma.

Make sure your doctor knows about all of the health problems you have. Having certain problems, such as kidney or liver disease, may affect how your doctor prescribes this medicine.

This medicine may cause you to become drowsy, dizzy, or less alert, which makes it harder for you to concentrate. If you are feeling sleepy, don't drive, operate machinery, or do anything else that could be dangerous to you or other people.

The oral medicines and intrathecal baclofen increase the sedating effects of alcohol and certain medicines, such as antihistamines that are used for cold, flu, and allergy relief.

Do not stop taking one of these oral medicines or intrathecal baclofen without first checking with your doctor. Stopping the medicine suddenly may cause unwanted side effects.

Dantrolene may cause liver damage. Frequent blood tests are needed to check liver functioning when a person is taking this medicine.

Injectable medicines tend to have a longer effect than oral medicines do. For example, botox usually begins to take effect within 3 days after injection, although the full effects are often not evident for 1 to 2 weeks. The effects of Botox last for about 4 to 8 months.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.

Women who use diazepam during pregnancy have a slightly higher chance of having a baby with birth defects. If you are pregnant or planning to get pregnant, you and your doctor must weigh the risks of using this medicine against the risks of not treating your condition.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerSusan C. Kim, MD - Pediatrics
Specialist Medical ReviewerLouis Pellegrino, MD - Developmental Pediatrics
Last RevisedSeptember 20, 2012

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