Rash under my arms after Botox that would go away within 4 months and reappear after each injection. Should I try Dysport?

However, if you have an actual allergy to Botulinum toxin, it will not really matter which brand you are exposed to.  If the rash is sufficiently bothersome, I would recommend discontinuing the injections.  One thing though, an actual allergy to botulinum toxin is unlike to last 4 months.  Have you discussed your situation with your physician?  If you are not being treated by a physician, consider see a board certified dermatologist.

I'm confused. Are you getting the injections into your underarms for hyperhidrosis? While you could have an allergy to botulinum toxin, this is extremely rare - I have seen it once in 15+ years of injecting. It is unlikely that any type of rash or response would last for 4 months and then go away. What I might recommend is a minimal dosage of Dysport be injected as a test, into the forearm. If you have a reaction, then an allergy would be what I would go with and you should not have any type of injections whether it be Botox, Dysport, etc. All of these products are fundamentally similar. "This answer has been solicited without seeing this patient and cannot
be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."