Do personal loans build credit?

A personal loan will indeed affect your credit, but whether a personal loan will improve your credit score or not depends on your ability to meet your monthly payments and eventually pay off the debt in full. As long as you make your monthly payments on time, and in full, that personal loan will help build your credit score. However, making late payments or stopping payments altogether will harm your credit score, whether for your personal loan or on other debt that you have.