Most drugs are measured in units of weight, for example 200mg of Ibuprofen. The botulinum products (Botox and Dsyport), however, are not. The measurement unit is actually just called a “unit”. Seems ridiculous, I agree. Now, to confuse things further, a unit of one of them is not the same as a unit of another. It is like miles versus kilometers; however you measure it, it is still the same distance from here to there. So, when describing how much of a botulinum product you received, you can’t just say, “I got 20 units”. You must specify “Botox units”, or “Dysport units” (or whatever brand). How each company came to decide how much of its product is a “unit”, no one knows. OK, well, probably someone knows, but it doesn’t matter. Officially, the companies will also say there is no conversion from their units to another branded unit. But in reality, there are some fairly well agreed upon conversions. For the two most common, Botox and Dysport, I considered it to be 2.5 units of Dysport is equal to 1 unit of Botox.

As far as cost, Botox usually costs about 3 times more per unit than Dysport, but since you use about 2.5 times more Dysport units to get the same result, the pricing works out pretty similar, usually slightly more for Botox.

Both products leave the factory as a dry material in a vial. Prior to use, the provider needs to liquify it by dissolving it into a saline solution. Each provider can decide for themselves how much liquid to add to that bottle. So, if you use 1cc of liquid to mix a bottle of Botox, you have 100 units per cc. As an example, if you give a patient ¼ cc, you would report 25 units, not ½ cc. But you could just as easily mix it with 2 or 3 cc’s or any amount provided it reasonably fits in the bottle. For this reason, you can never quantify how much Botox or Dysport you gave by volume, always by units.

There are reasons to make your botulinum product more potent and reasons to make it more dilute. A more concentrated solution creates more waste because you leave a tiny bit of liquid in the syringe and needle after you’re done, and some will be left in the bottle at the end. It also means that you will have more error in your injection since there will always be a small error in how much is injected with each press of the syringe plunger. If the solution is double the concentration, your error will be double. As another consideration, a more concentrated solution will be less likely to spread from the spot it was injected. Usually this is desired, but in some treatments, you actually want it to spread a bit. For most applications, I mix Botox as 50 units per cc and Dysport as 125 units per cc. The result of this is that to get a given result, I use the same VOLUME of each product for any particular use. For example, 20 units of Botox or 50 units of Dysport is a common treatment for the glabella (area between the eyebrows). At my dilution, I would use the same volume for either, .4cc’s. Standardizing the volume reduces the risk of error since treating with either product is done the same, only the mixing of the bottle is done differently.

Dysport and Botox are very similar when given in comparable doses, I suspect most patients would not be able to tell a difference. If you are looking for it, you will probably notice that Dysport takes effect faster, usually 2 or 3 days vs 5 to 7 for Botox. As far as duration, both products last 3 to 6 months for facial muscle treatments, usually longer on people who do it more consistently. Also, some muscle groups consistently last longer, for example, the scowl muscle (area between the eyebrows) is one of the longer lasting areas, 6 months sometimes, whereas the crow’s feet area rarely lasts much longer than 3 months.