Dehydration and Erections lead to decreased blood volume, which can result in lower blood flow. Since achieving and maintaining an erection relies on increased blood flow to the penis, reduced circulation can make it difficult to achieve an erection. Dehydration can affect hormone levels, including testosterone, which plays a crucial role in sexual desire and function. Lower testosterone levels can lead to decreased libido and erectile issues. Adequate hydration is essential for proper nerve function. Dehydration can impair nerve signaling, which is vital for the process of achieving an erection.