Why does my dysport fade after only 3 weeks?

It's rare, but some people can be fast metobolizers. You can try Xeomin as an alternative to Dysport or Botox. See an expert. Best, Dr. Emer

Dear Anne 
Thank you very much for your question.
I hope that you understand how toxins work: they kill the nerve endings that go to the muscles.
This is good - were they to stay dead you would have a lifelong result from one injection!!
They do come back to life and new nerve endings generate and this is when you sense it is wearing off.
My purely personal observation is that those that are very strong (ie have deeper lines to start with) start moving quicker. Also those who cannot stop themselves frowning etc find the effect wears off quicker.
The type of toxin seems to make less difference although in my hands I get best results with genuine Botox.
So I guess the rather unsatisfactory answer is that it is a bit like someone who bites their nails - you have to get out of the habit as quickly as possible and this will save you a fortune because the effect will take much longer to wear off.
I do hope this helps.
Kind Regards 
Dr Dinesh Maini