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Overview: Myobloc is commonly used to treat cervical dystonia and sialorrhea. The most common side effects are dry mouth, trouble swallowing, pain near the injection site, and headache. Serious side effects are less common but can include problems breathing, speaking or swallowing, and botulism. Myobloc is an injection given to you by a healthcare provider.

Uses

What is Myobloc used for?

Myobloc (rimabotulinumtoxinB) is commonly used for the following conditions.

  • A painful movement disorder causing your head to twist and turn or be pulled backward or forward due to muscle contractions in your neck (cervical dystonia)
  • A problem when your mouth makes too much spit (sialorrhea)

Myobloc may also be used for other conditions as determined by your healthcare provider.

How does Myobloc work (mechanism of action)?

For cervical dystonia, Myobloc works to reduce spasms and pain by blocking certain nerve signals and reducing muscle activity at the site where it is injected. 

For sialorrhea, Myobloc reduces the amount of spit your mouth makes by reducing the release of acetylcholine. Acetylcholines is a natural chemical in your body that increases spit production 

How is Myobloc supplied (dosage forms)?

Brands and other names

  • Myobloc

Myobloc is available as an injection that is given by a healthcare provider.

How should I store Myobloc?

Myobloc is usually given by a healthcare provider in a hospital or clinic. If you will store Myobloc at home, follow the instructions given by your healthcare provider.

Side Effects

What are the most common side effects of Myobloc?

The most common side effects of Myobloc are listed below. These side effects may vary depending on your age, the condition being treated, and where you receive your injection. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dry mouth
  • Trouble swallowing
  • Pain near the injection site
  • Headache

There may be other side effects of Myobloc that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of Myobloc?

While less common, the most serious side effects of Myobloc are described below, along with what to do if they happen.

Severe Allergic Reactions. Myobloc may cause allergic reactions, which can be serious. Stop using Myobloc and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Spread of Toxin Effects. The medicine in Myobloc may affect areas of your body away from the injection site. This may cause symptoms of a serious condition called botulism. Symptoms of botulism can start within hours, days, or weeks after your dose. Contact your healthcare provider right away if you have any of the following symptoms of botulism.

  • Loss of strength or muscle weakness all over the body
  • Double vision, blurred vision, and drooping eyelids
  • Losing your voice, changes in your voice, hoarseness, or trouble saying words clearly (dysarthria)
  • Loss of bladder control
  • Trouble breathing or swallowing

Breathing, Swallowing, or Speaking Problems. Myobloc may cause problems with breathing, swallowing or speaking. This can be serious or life-threatening. This is caused if the muscles you use to breathe and swallow become weak after the injection. It can happen hours, days, or weeks after your dose. Swallowing difficulties can last for several months. People who have trouble swallowing may need a feeding tube to get food and water. If swallowing issues are severe, food or liquids could get into your lungs. Get emergency medical help right away if you have trouble breathing, swallowing, or speaking.

Warnings & Precautions

Who should not use Myobloc?

Allergies to Ingredients. People who are allergic to any of the following should not use Myobloc.

  • RimabotulinumtoxinB
  • Myobloc
  • Any other medicine known as a botulinum toxin product
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Myobloc.

Skin Infection at the Injection Site. Myobloc should not be injected into skin that is infected. Tell your healthcare provider if you have any symptoms of skin infection, such as redness, pain, swelling, warm skin, or blisters.

What should I know about Myobloc before using it?

Do not use Myobloc unless it has been prescribed to you by a healthcare provider. Your healthcare provider will store and give you the medicine. 

Myobloc may cause loss of strength, muscle weakness, vision problems, or drooping eyelids within hours, days, or weeks after an injection. If any of these happen to you, do not drive or do other activities that require alertness or coordination.

What should I tell my healthcare provider before using Myobloc?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if Myobloc is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Muscle or nerve disorders, such as amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease, myasthenia gravis, or Lambert-Eaton syndrome
  • Breathing problems, such as asthma or emphysema
  • Swallowing problems
  • Plans to have surgery
  • Past surgery on your face
  • Bleeding problems
  • Muscle weakness in or near the planned injection site
  • Drooping eyelids

Other Medicines and Supplements. Myobloc may interact with other medicines and supplements. Before using Myobloc, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how Myobloc could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. 

Breastfeeding. It is not known if Myobloc passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should use Myobloc while breastfeeding.

How can I get more information about Myobloc?

For more information about Myobloc, you can visit the manufacturer’s website at www.myobloc.com or call them at 888-461-2255.

Interactions

Does Myobloc interact with foods or drinks?

There are no known interactions between Myobloc and foods or drinks.

It is unknown if drinking alcohol will affect Myobloc. If you have blurred vision from Myobloc, alcohol may worsen this effect. 

Does Myobloc interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using Myobloc.

  • A botulinum toxin product, such as incobotulinumtoxinA (Xeomin), onabotulinumtoxinA (Botox, Botox Cosmetic), daxibotulinumtoxinA (Daxxify), prabotulinumtoxin A (Jeaveau), or abobotulinumtoxinA (Dysport), which is a medicine commonly used to reduce wrinkles or spasms.
  • An aminoglycoside antibiotic, such as amikacin or gentamicin, which is given by injection to treat infections
  • An anticholinergic medicine, which includes antihistamines and medicines commonly used for overactive bladder, Parkinson’s disease, or stomach problems
  • A muscle relaxant, such as carisoprodol (Soma), cyclobenzaprine, or tizanidine (Zanaflex)
  • A sleep medicine, such as temazepam (Restoril), zolpidem (Ambien and others), or eszopiclone (Lunesta)
  • Aspirin, which is in many prescription and OTC products including those for pain, swelling, and fever
  • An antiplatelet medicine, such as clopidogrel (Plavix), ticagrelor (Brilinta), aspirin/dipyridamole, or cilostazol, which is a medicine used to prevent blood clots
  • A blood thinner, which is a medicine used to treat or prevent blood clots

This may not be a complete list of medicines that can interact with Myobloc. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much Myobloc?

If you or someone else has used too much Myobloc, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of Myobloc?

Myobloc is usually given by a healthcare provider in a clinic. Your healthcare provider will make sure you are receiving Myobloc as scheduled.

If you miss an appointment to get your Myobloc dose, call to make another appointment as soon as possible.