Botulinum toxin is produced by Clostridium botulinum, a gram-positive anaerobic bacterium.  The clinical syndrome of botulism can occur following ingestion of contaminated food, from colonization of the infant gastrointestinal tract, or from a wound infection. It is broken into 7 neurotoxins labelled as types A, B, C [C1, C2], D, E, F, and G). Although they differ, they are structurally similar. Human botulism is caused mainly by types A, B, E, and (rarely) F. Types C and D cause toxicity in animals only.

There are various botulinum toxins on the market, and they all possess individual potencies. Care is required to assure proper use and avoid medication errors. There are currently two different types of botulinum toxin commercially available in the United Kingdom – type A toxin (including the brands Botox®, Vistabel®, Dysport®, Azzalure® and Xeomin® and Bocouture®) and type B toxin (Neurobloc®).

Botulinum Toxin Type A is the wrinkle reducing injection treatment. It’s also known as Botox®, which is actually a brand name supplied by Allergan. These treatments were first licensed for cosmetic use in the early 2000’s. is Vistabel® is manufacturerd by the same company. Azzalure® and  Dysport®  are manufacture by Galderma Bocouture® and Xeomin® are manufactured by Merz Pharmaceuticals



All the products are well tested and understood, but there are some important differences to know. Before even looking at the products, remember that the units are not equivalent. Botulinum toxins are all very small proteins, but their power resides not in weight but in their ability to continuously work away and cleave the receptor complex on the presynaptic membrane many times over. For this reason, units are a measure of biological activity rather than weight or volume. Allergan use a cellular assay to measure Botox units.  Speywood units are quantified as the amount of botulinum toxin that kills 50% of a genetically homogeneous population of mice

Each company produces different aesthetic and non-aesthetic licenced products, often with the same molecule but in different sized vials. Galderma make a product aimed at the aesthetic market called Azzalure which contains 125 speywood units and Dysport, which comes in vials of 500 speywood units. The molecule is called abobotulinumtoxinA.  Azzalure is not a brand that was launched in the USA, where you will only come across Dysport. Merz produce Boucoture and Xeomin, also aimed at aesthetic and general medical uses respectively and it’s molecule is called incobotulinumtoxinA. Allergan did at one stage produce Vistabel and Botox, but now produce three different sized vials labelled ‘Botox’, with 50, 100 and 200 Allergan units. This molecule is called onabotulinumtoxinA. Manufacturers and their representatives hotly contest many of the differences that are claimed by their competitors, and there are studies to support each view. It is generally widely accepted that there are a few clinically important differences.


It is generally observed that Merz’s product and Allergan’s product diffused similarly but significantly less than Galderma’s offering.  Clinically this has led to many clinicians preferring particularly the more established brand leader for more precise treatments such as in the lower face (often at a more concentrated dilution to further increase precision). However, Galderma’s product is often chosen over the others for treatment of hyperhidrosis, since in theory a greater spread is advantages where little accuracy is required.

Speed of onset:

Azzalure/Dysport is also significantly quicker in terms of onset. This is occasionally contested by representatives, but rarely by anyone who uses both products routinely- Clients will quite often report that they experience a rather more sudden and earlier onset with Azzalure/Dysport than with either Boucoture/Xeomin or Botox.


The unique ability of the incobotulinuma molecule from Merz to remain biologically active even when stored for long periods at room temperature is largely due to its purified form, and the complete removal of the usual stabilising protein complex. It has been suggested that the lack of stabilising proteins could decrease resistance to the molecule, but it’s worth remembering that these proteins separate early after injection df, and it is antibodies to the active botulinum toxin unit that are required to produce true resistance. Overall, all the products are safe to use in trained hands. The differences for many standard treatments are small and often more of academic or subtle interest rather than a stark difference in results for your client.

50 units of Botox/Bocouture = 125 units of Azzalure

If reconstituted according to label, 2-3 units of Azzalure = 1 unit of Botox/Bocouture

I tend to make up a syringe of Azzalure with 1ml of bacteriostatic saline and use like Botox.



So, 50 Unit Vile of Botox will be diluted in 1 ml of bacteriostatic saline.

How to read a syringe