Botox: pain relief mechanism


Botulinum A Toxin is produced by Clostridium botulinum which affects the presynaptic membrane of the neuromuscular junction where it prevents acetylcholine release and therefore muscle contraction.  Inactivation persists until collaterals form in junction plates on new areas of muscle cell walls.

An investigational use of Botulinum toxin is for pain management, the purported mechanism of action is a reduction in spasticity in both dystonias and migraines. Results in headaches have been inconsistent, and negative for myofascial trigger points, orofacial pain, and neck pain.

Side effects of Botulinum toxin include pain, erythema, and unintended paralysis of nearby muscles.

Botulinum Toxin for Pain Relief

  • Mechanism of Action: reduction in spasticity (prevents presynaptic ACh release)
  • May be Helpful: headache
  • Not Helpful: myofascial trigger points, orofacial pain, and neck pain
  • Side Effects: pain, erythema, and unintended paralysis of nearby muscles

A recent meta-analysis by Jackson et al. showed that there was a modest benefit for chronic headaches/migraines, but it did not reduce the quantity of headaches, and did not help with tension headaches. A Cochrane review by Soares et al concluded there was not enough evidence to support botox use for myofascial pain syndrome and that more RCTs are needed.


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Botulinum toxin: Mech of action



  1. Adriana Soares, Régis B Andriolo, Alvaro N Atallah, Edina M K da Silva Botulinum toxin for myofascial pain syndromes in adults. Cochrane Database Syst Rev: 2012, 4;CD007533
  2. Jeffrey L Jackson, Akira Kuriyama, Yasuaki Hayashino Botulinum toxin A for prophylactic treatment of migraine and tension headaches in adults: a meta-analysis. JAMA: 2012, 307(16);1736-45