There are eight different types of botulinum toxin produced by C. botulinum; A, B, C1, C2, D, E, F, and G. All work by blocking the release of acetylcholine, one of the most significant neurotransmitters in our body. Acetylcholine activates muscles, so blocking it causes muscle relaxation and paralysis. Injections enable the botulinum toxin to be targeted directly into specific muscles. There it has a direct effect on acetylcholine in the nerve synapses, preventing signals that would normally cause the muscle to contract.

Type A is the most potent and longest lasting, followed by types B and F. Currently, preparations containing Type A and B are commercially available and include:

• OnabotulinumtoxinA (Botox, Botox Cosmetic)
• AbobotulinumtoxinA (Dysport)
• IncobotulinumtoxinA (Xeomin)
• PrabotulinumtoxinA-xvfs (Jeuveau)
• RimabotulinumtoxinB (Myobloc).

All have different potencies and are not interchangeable; care needs to be taken so that the correct dosage stated is used for that product. Each manufacturer uses assay methods specific to their company, so even though dosages may be quoted in similar sounding units, potency varies several-fold between the different products. Approved indications also vary.

Effects are usually seen within 24-72 hours and peak around ten days. Effects last about two to four months or until new nerve terminals sprout and form new synaptic contacts.