Reviewed on 9/19/2023

What Is RimabotulinumtoxinB and How Does It Work?

RimabotulinumtoxinB is a botulinum toxin indicated for cervical dystonia to reduce the severity of abnormal head position and neck pain associated with cervical dystoniaused for the treatment of cervical dystonia. RimabotulinumtoxinB is also used for the treatment of chronic sialorrhea.

  • RimabotulinumtoxinB is available under the following different brand names: Myobloc

What Are Side Effects Associated with Using RimabotulinumtoxinB?

Common side effects of RimabotulinumtoxinB include:

  • injection site reactions (muscle weakness, redness, bruising, infection, and pain)
    • headache
    • joint or back pain
    • dry mouth
    • nausea
    • upset stomach
    • fever
    • cough
    • sore throat
    • flu symptoms
    • pain or stiffness in the neck
    • dizziness
    • drowsiness
    • anxiety
  • Serious side effects of RimabotulinumtoxinB include:
  • Rare side effects of RimabotulinumtoxinB include:
    • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, coordination loss, unsteady, very stiff muscles, high fever, profuse sweating, or tremors
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, light-headedness, or passing out

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are the Dosages of RimabotulinumtoxinB?

Adult dosage

Injectable solution

  • 5000 units/mL (single-dose vial)

Cervical Dystonia

Adult dosage

  • Prior botulinum toxin injection: 2500-5000 units IM, divided among affected muscles
  • No prior botulinum toxin injection: Lower initial dose
  • Determine subsequent dosing based on the patient’s individual response
  • Duration of effect observed in studies between 12-16 weeks at doses 5,000-10,000 units

Chronic Sialorrhea

Adult dosage

  • 1,500-3,500 units, divided among parotid and submandibular glands via intraglandular administration
  • Parotid gland: 500-1,500 units/gland
  • Submandibular gland: 250 units/gland
  • Consider the patient's response to treatment when determining the frequency and dose of subsequent treatments; no more frequent than every 12 weeks
  • The duration of the effect of each treatment is usually up to 3 months; varies among patients

Dosage Considerations – Should be Given as Follows:

  • See “Dosages”

What Other Drugs Interact with RimabotulinumtoxinB?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, healthcare provider, or pharmacist first.

  • RimabotulinumtoxinB has severe interactions with no other drugs.
  • RimabotulinumtoxinB has serious interactions with the following drugs:
    • abobotulinumtoxinA
    • amikacin
    • amphotericin B deoxycholate
    • capreomycin
    • clindamycin
    • neomycin oral
  • RimabotulinumtoxinB has moderate interactions with at least 33 other drugs.
  • RimabotulinumtoxinB has minor interactions with the following drugs:
    • acetazolamide
    • clonazepam
    • nimodipine

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, health questions, or concerns.

What Are Warnings and Precautions for RimabotulinumtoxinB?


  • Hypersensitivity to any botulinum toxin product or any of the components in the formulation
  • Infection at the proposed injection site

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using RimabotulinumtoxinB?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using RimabotulinumtoxinB?”


  • Postmarketing safety data and other approved botulinum toxins suggest that botulinum toxin effects may, in some cases, be observed beyond the local injection site
  • Potency units are not interchangeable with other preparations of botulinum toxin products and, therefore, units of biological activity of RimabotulinumtoxinB cannot be compared to or converted into units of any other botulinum toxin products assessed with any other specific assay method
  • Serious hypersensitivity reactions (eg, angioedema, urticaria, rash) have been reported with botulinum toxin products
  • Product contains albumin; based on effective donor screening and product manufacturing processes, it carries an extremely remote risk for transmission of viral diseases and variant Creutzfeldt-Jakob disease
  • Peripheral motor neuropathic diseases (eg, ALS, motor neuropathy)
  • Neuromuscular junctional disorders (eg, myasthenia gravis, Lambert-Eaton syndrome)
  • Increased risk for severe dysphagia and respiratory compromise in pts with neuromuscular disorders
  • Drug interaction overview
    • Coadministration with aminoglycosides or other agents interfering with neuromuscular transmission (eg, curare-like compounds) may potentiate effects of the toxin; use with caution
    • Use of anticholinergic drugs after administration of rimabotulinumtoxinB may potentiate systemic anticholinergic effects
    • Excessive weakness may be exaggerated by the administration of a muscle relaxant before or after the administration of rimabotulinumtoxinB
  • Other botulinum neurotoxin products
    • The effect of administering different botulinum toxin products at the same time or within several months of each other is unknown
    • Excessive neuromuscular weakness may be exacerbated by administration of another botulinum toxin prior to the resolution of the effects of a previously administered botulinum toxin

Pregnancy and Lactation

  • There are no adequate data on the developmental risks associated with use in pregnant women
  • No developmental toxicity was observed in pregnant rats administered rimabotulinumtoxinB by IM during gestation and lactation, at doses producing maternal toxicity
  • Lactation
    • There are no data on the presence of rimabotulinumtoxinB in human milk, the effects on the breastfed infant, or the effects on milk production
    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for therapy and any potential adverse effects on the breastfed infant from therapy or any underlying maternal condition

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