Here are some links to Medical based websites on the subject of Aquagenic Pruritus that site Beta Alanine as a treatment, so if your dermatologist or any other doctor has looked into it, they would find the information.
I have belonged to a FB Groups for Aquagenic Pruritus for 8+ years and based on members posts, I would estimate that 99% of dermatologist have no clue.
I have been taking this for 7 years, usually 2 to 3 times per day. I have not had any issues with Beta Alanine. It is a amino acid found in our bodies...maybe I have a deficiency and that is why it works?? Who Knows...I'm just glad it works.
https://www.researchgate.net/publication/375122684_Aquagenic_Pruritus_A_web-based_survey_study_exploring_itch_characteristics_therapeutic_options_and_patient_perspectives
https://pubmed.ncbi.nlm.nih.gov/33170524/
https://my.clevelandclinic.org/health/diseases/22516-aquagenic-pruritus
https://dermnetnz.org/topics/aquagenic-pruritus