Why can't I use an alcohol based toner after dermapen?

We do our micro-needling with autologous platelet rich plasma, if your micro-needling treatment was done with only a peptide gel (or something like it) than it is not as reactive, and the inflamation response is not as important. But it is still a good idea to wait and let your skin heal naturally without any harsh acids or alcohol based compounds.

Thanks for the question.  Microneedling(including Dermapen) produces results by puncturing the skin at depths set by the provider.  Following the procedure the protective layer of you skin has been punctured with tiny holes in many places and alcohol based products will increase the irritation to the underlying tissue.  Similar to how alcohol based products(hand sanitizer for example) burns if you've ever had even a small amount placed on an open wound.  Alcohol will not only increase the inflammatory response(not in a positive way here) but also is extremely drying to skin.