What is Myobloc: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Myobloc overview

BRAND NAMES:

  • Myobloc

Generic Names:

  • Myobloc

Uses:

  • Treats the abnormal head position and neck pain that result from cervical dystonia (severe muscle spasms of the neck). Also treats chronic sialorrhea (drooling or excessive salivation). This is a botulinum toxin B type product.

Therapeutic Classes:

  • Musculoskeletal Agent, Cervical Agent

Forms:

  • Injectable

How it’s taken:

  • By injection

What is Myobloc used for?

What form(s) does Myobloc come in

  • Injectable

What are common Myobloc doses?

  • Vial 0.5ML of 2500UNIT/0.5ML

  • Vial 1ML of 5000UNIT/ML

Common Myobloc prescriptions

  • Myobloc
    0.5ml of 2500unit/0.5ml vial

  • Myobloc
    1ml of 5000unit/ml vial

  • Myobloc
    2ml of 10000unit/2ml vial

How to take Myobloc

  • Injection routeYour doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot into one of your muscles.

  • Injection routeA nurse or other health provider will give you this medicine.

  • This medicine works slowly. Improvement often starts within 2 to 4 weeks after the injection. The effects usually last 12 to 16 weeks.

  • Your doctor will only use rimabotulinumtoxinB (Myobloc®) to treat your condition. Other botulinum toxin products may not work the same way.

  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

  • Missed dose: Injection routeCall your doctor or pharmacist for instructions.

  • Injection routeYour doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot into one of your muscles.

  • Injection routeA nurse or other health provider will give you this medicine.

  • Your doctor will only use rimabotulinumtoxinB (Myobloc®) to treat your condition. Other botulinum toxin products may not work the same way.

  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.

  • Missed dose: Injection routeCall your doctor or pharmacist for instructions.

  • This medicine works slowly. Improvement often starts within 2 to 4 weeks after the injection. The effects usually last 12 to 16 weeks.

What to do if you miss a dose of Myobloc

  • Injection routeCall your doctor or pharmacist for instructions.

Myobloc contraindications

  • This medicine is not right for everyone. Do not receive it if you had an allergic reaction to rimabotulinumtoxinB or any type of botulinum toxin product, or you have an infection in the skin where the shot will be given.

Myobloc warnings

  • Tell your doctor if you are pregnant or breastfeeding, or if you have breathing problems (including asthma, emphysema), bladder problems, bleeding problems, a droopy eyelid, nerve or muscle problems (including amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), Lambert-Eaton syndrome, myasthenia gravis), or speaking or swallowing problems. Tell your doctor if you have plans to have surgery, or have had surgery on your face.

  • This medicine may cause serious muscle reactions (including trouble with swallowing, talking, or breathing), which can be life-threatening.

  • One part of this medicine is made from donated human blood. Some human blood products have transmitted certain viruses to people who have received them. The risk of getting a virus from medicines made of human blood has been greatly reduced in recent years. Although the risk is low, talk with your doctor if you have concerns.

  • This medicine may make your muscles weak and cause vision problems. Avoid driving, using machines, or doing anything else that could be dangerous if you feel weak or are not able to see well.

  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

  • Unusual muscle weakness or paralysis (may occur several weeks after you receive this medicine).

Myobloc interactions

  • Some medicines can affect how this medicine works. Tell your doctor if you are using medicine for infection (including amikacin, gentamicin, neomycin, netilmicin, streptomycin, tobramycin) or a muscle relaxant that would be used during surgery (including atracurium, gallamine, pancuronium, tubocurarine, vecuronium).

  • If you need to receive an injection of any botulinum toxin product within 4 months after receiving this medicine, tell the doctor when you last received a dose of rimabotulinumtoxinB.

  • Serious muscle reactions have been reported within hours to weeks after receiving this medicine. If you start to have muscle weakness or trouble with swallowing, talking, or breathing, call your doctor right away. In some situations, these problems could be life-threatening and may require treatment in a hospital or clinic.

  • This medicine may make your muscles weak and cause vision problems. Avoid driving, using machines, or doing anything else that could be dangerous if you feel weak or are not able to see well.

  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.

Myobloc side effects

Serious Side Effects

  • Loss of bladder control

  • Pain in the neck

  • Trouble with breathing, speaking, or swallowing

  • Unusual muscle weakness or paralysis

  • Redness, pain, tenderness, bruising, swelling, or weakness where the shot was given.

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

  • Blurred vision, double vision, drooping of the eyelids

  • Change or loss of voice

  • Fever, chills, cough, stuffy or runny nose, sore throat, and body aches

Less Serious Side Effects

  • Dry mouth

  • Redness, pain, tenderness, bruising, swelling, or weakness where the shot was given.

  • Dizziness, headache

  • Headache.

  • Redness, pain, tenderness, bruising, swelling, or weakness where the shot was given

  • Nausea or stomach upset.

  • Lack or loss of strength.

  • Back or joint pain

  • Nausea or stomach upset

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