What is the Significance of a Rash After a Dysport Treatment?

Thank you for your question. A side effect that may occur, which in my experience is uncommon, is an allergic reaction to the neurotoxin. In people with an autoimmune condition, it can cause the immune system to become hyperactive, causing a rash. It is best to get an evaluation by your injector if you experience these types of side effects. Be certain to be under the supervision of a board certified dermatologist or plastic surgeon with expertise in injectables for an evaluation and for the safest and most effective treatments. I hope this helps.

Allergic reactions to botlinum toxin treatement following Dysport or Botox is very rare.

An allergic reaction like this to a botulinum toxin product is quite rare.  So rare that routine allergy testing is not recommend.  However for an individual with a history of a vague prior reaction, allergy testing is a reasonable consideration.  

I have never seen a rash from botox or disport but have had patients that have had allergy to something that was put on face prior to injecting-cleaning product or anesthetic.