What is the Likelihood of an Allergic Reaction to Juvederm after a Reaction to Botox?

Allergies to Botox and Juvederm, and Restylane, are extremely rare. If you had a reaction, it might be a different type of reaction other than allergy. The botox molecule and the hyaluronic acid molecule in Juvederm are completely different, so even if you were allergic to one, you shouldn't be allergic to the other.

Assuming that you in fact had an actual allergy to BOTOX, the likelihood of you also having an allergy to Juevederm is very low but not zero.  If you are concerned about this, I recommend that you have your cosmetic surgeon apply a test injection of Juvederm somewhere inconspicuous like the arm.  If you have no reaction to the injection after 10 days then it is improbable you will have an issue with the product.  Just remember that allergies can develop anytime.  So if you think you are having a problem, immediately bring this to the attention of your injecting physician.

Botox and Juvederm are not at all the same so a cross reaction would be unlikely unless there is something in common to both such as a preservative etc.. that I am unaware of. You could ask Allergan that before injecting. Without knowing the nature of your "allergic reaction" the only other thing that I can think of that could be common to both is an allergy to something that the doctor uses on your face prior to injection. Make sure you discuss this with your doctor. I have seen reaction to my numbing cream.