Are There Different Strengths or Concentrations of Botox?

How the Botox is reconstituted depends on the injector. However, if you are paying by unit then that measures the actual Botox product, rather than the reconstituted product. 

There are many factors that affect Botox. First, the dilution which leads to the final concentration, since different concentrations lead to different amounts of Botox per volume injected. Second, the time period since the dilution since the Botox degrades after being reconstituted and before being injected. Third, the injection technique can affect Botox result, so there there may not be consistency between injectors. Good luck.

There are several ways to mix the Botox. Some use a more dilute formula than others.   Some may inject more than others. 

Each time you get Botox, providing you get reinjected just as the muscle function begins to return, you should get the same effect or even better over time. If the effects are not lasting as long it is likely the the number of units injected has been changed. You need to verify the number of units are are receiving and thus paying for.
I'm not sure why the increased pain. Although the 30 gauge needle that is used gets dull very quickly and this increases the pain with each successive puncture. I often have to change the needle once or twice with each patient just for this reason.

I totally agree with the other doctors. In addition, as noted, we usually dilute Botox to make it ready for injection. We can use different solutions for dilution, for example saline with or without preservatives. It may affect the pH (acidity) of the Botox solution, and the more acidic it is, the more it will sting. If the solution stays without use for a long time, it may also lose effect, at least partially. It may happen if the office uses Botox only occasionally, and keeps the bottle open for a long time.
I would go back to the doctor's office and talk to them about these two possibilities, in addition to the number of units used. The feedback is always useful. Hopefully, it will work better for the next injection.

Botox is the brand name for a product made by Allergan USA. The product contains a material (Botulinum Toxin) that is produced in nature by a bacteria.
As of this writing, Botox is the only formulation that is currently FDA approved for cosmetic use in the USA. Other products are in the pipeline.
The product is supplied in a vial that contains 100 units of freeze dried Botulinum toxin. Since it is freeze dried, it must be diluted with a liquid in order to be injected. The recommended liquid is saline (salt water).
As you can imagine, the concentration of the product can vary depending on how much liquid is added.
Generally speaking adding too much saline (watering it down) can make the Botox less effective. This approach is used by people who advertise a very low price for the Botox to lure you in. Watering down the Botox will give you a result that is not as effective and will not last as long.
There are several other factors that determine how effective Botox is, and how long it lasts.
1. Only about 80% of patients respond to Botox
2. Although most patients see the result within a week. In some patients the full effect is not observed until 1 month.
3. Older patients don't respond to Botox as well as younger patients.
4. In approximately 25% of patients, Botox is still effective after 4 months.
5. Women generally respond better to Botox than men.
6. Each individual will respond slightly differently to the effects of Botox.
7. In some areas of the face, Botox lasts longer than other areas.
8. Repeated use of Botox causes weakening and thinning of the muscle which can take some time to recover. Furthermore, it may take a while for the muscle to regain its full strength.
Good luck.

Botox comes as a freeze-dried 100 unit vial. The vial is typically mixed with a variable volume of fluid for injection. More important than the concentration of Botox is the actual number of units (which reflects the number of protein molecules) used. Perhaps you did not receive the same number of units the last two injection sessions. Some individuals can have decreased effects of Botox injections even with the same number of units. Rarely, people can develop antibodies to Botox. In these cases, Botox injections essentially have no effect.
Good luck.

Hello
Botox can be diluted in several different ways, depending on each doctor's preference. However, the number of units injected is what you need to know. One can inject the same number of units using different dilutions (the more dilute the mixture, the greater volume that needs to be injected). No matter how it is diluted out of the bottle, 25 Units of Botox is 25 Units of Botox.
If your doctor has injected the same amount each time (and you have the same person injecting you each time) , but you notice less of an effect, you may need more Botox. That happens not that infrequently. Over time, we age, our muscles change and that may mean more Botox to get the same effect. So ask how many units you got and make a plan together with your doctor for the next injection. Best of luck.

First, the amount of BOTOX is not as important as the dilution. If the same amount of BOTOX was administered but the dilution was increased, you would have received fewer units. Different physicians utilize different dilutions. Some of us, including myself, use different dilutions in different areas. For instance, I like the least dilution possible if I am injecting under the eye or around the mouth. I want precision and do not want diffusion. This would require a dilution of I cc in a 100 unit vial. I have seen some excellent BOTOX adminstrators use a 10 cc dilution very effectively. This physician was adminstering 10 times the amount of BOTOX as I was, but the effect would be roughly the same since the units are the same.
If your physician was indeed using the same number of units each time. There could be other factors at work. He/She might have used a different diluent. Allergan still recomends in their product insert to use non-reserved saline. Maybe the physician had a pang of guilt that he/she was doing something off label ( nearly all of us use presserved saline by the way), and decided to use unpreserved saline the second time. This does not last as long, hence is weaker, and might account for the less powerful effect.
Also, the preserved saline uses benzyl alcohol as its perservative. This has an anesthetic quality to it. Using a preservative leads to less painful injections. You would have had the benefits of this less painful experience, the first time, but if the diluent was switched to unpreserved saline, not the second time.
Finally, perhaps a different needle was used. Your injector might have used a 31 gauge needle the first time. Found it difficult to use ( it is a little bit, since it requres less pressure and BOTOX can leak out), and switched to the 30 gauge needle. The larger gauge needle being a bit more painful.
We are all speculating here. It would be much easier to voice your concerns and questions, the the physician who injected it and the mystery would be solved.