Yes, alcohol can decrease the benefits of prescribed antibiotics. When alcohol is consumed while taking antibiotics, it can reduce the absorption of the medication, decreasing its effectiveness in fighting off infection [2]. Furthermore, alcohol can irritate the lining of the stomach, which can exacerbate any stomach-related side effects of the antibiotics [3]. Moreover, alcohol can also weaken the immune system, making it harder for the body to fight off infection [2]. Therefore, it is generally recommended to avoid alcohol while taking antibiotics [1][2][3].

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/ALCOHOL>
[2] <https://www.alcoholrehabguide.org/alcohol/drinking-drugs/antibiotics/>
[3] <https://www.healthline.com/health/antibiotics-alcohol>