The aim of pharmacogenetics is to reduce adverse reactions to medicines. For some medicines supported by robust scientific evidence, pharmacogenetic recommendations clearly help to prevent these reactions.
Even so, other factors also play a role: variants that have not been analysed, other diseases, other medicines and your lifestyle. Your results should therefore always be assessed with your doctor before you make any decision.
A pharmacogenetic test is not currently mandatory before taking most medicines. Organisations such as the FDA, CPIC and DPWG publish guidance on its use, but recommendations vary according to the medicine and the available evidence.