BACKGROUND AND OBJECTIVES: Botulinum toxin (BTX) is one of the most potent 
bacterial toxins known and its effectiveness in the treatment of some pain 
syndromes is well known. However, the efficacy of some of its indications is 
still in the process of being confirmed. The objective of this study was to 
review the history, pharmacological properties, and clinical applications of BTX 
in the treatment of pain of different origins.
CONTENTS: Botulinum toxin is produced by fermentation of Clostridium botulinum, 
a Gram-positive, anaerobic bacterium. Commercially, BTX comes in two 
presentations, types A and B. Botulinum toxin, a neurotoxin with high affinity 
for cholinergic synapses, blocks the release of acetylcholine by nerve endings 
without interfering with neuronal conduction of electrical signals or synthesis 
and storage of acetylcholine. It has been proven that BTX can selectively weaken 
painful muscles, interrupting the spasm-pain cycle. Several studies have 
demonstrated the efficacy and safety of BTX-A in the treatment of tension 
headaches, migraines, chronic lumbar pain, and myofascial pain.
CONCLUSIONS: Botulinum toxin type A is well tolerated in the treatment of 
chronic pain disorders in which pharmacotherapy regimens can cause side effects. 
The reduction in the consumption of analgesics and length of action of 3 to 4 
months per dose represent other advantages of its use. However, further studies 
are necessary to establish the efficacy of BTX-A in chronic pain disorders and 
its exact mechanism of action, as well as its potential in multifactorial 
treatments.