Regular use of Sildenafil twice a week will not cause problems with achieving an erection without a drug, but over time, however, tolerance to a low dose may develop, and consequently the need to increase it. There is a possibility that long-term reliance on Sildenafil to achieve an erection may affect the natural mechanisms that regulate erection. However, this is a very individual matter, difficult to estimate on the basis of such a short description. Therefore, it is worth contacting a urologist to identify the cause of your problems. The GdziePoLek.pl service also allows you to obtain a teleconsultation with a doctor: https://www.gdziepolek.pl/telekonsultacja/z-urologiem A colleague also answered a similar question in the thread: https://www.gdziepolek.pl/opinie-i-pytania/47613/sildenafil-czy-dlugotrwale-przyjmowanie-50-mg-sildenafilu-raz-na-tydzien-moze-prowadzic-do-uzaleznien I enclose materials that may be interesting: https://www.gdziepolek.pl/kategorie/leki-na-potencje https://www.gdziepolek.pl/substancje/sildenafil