I can understand your concern regarding the pain and discomfort especially if the injections are done manually using the sharp needle.
To minimise the discomfort of the Rejuran procedure, I prefer to use an injector gun which can be calibrated to deliver a precise amount at a precise depth.
The needles used are also superfine 31G. To make it more comfortable most doctors will also mix it with a very small amount of lidocaine. This is unlikely to affect the efficacy of the product.
Hope this helps.