Silditop 100 (which contains Sildenafil Citrate, the same active ingredient found in Viagra) can potentially cause back pain as a side effect, though it is relatively uncommon. Back Pain as a Side Effect of Sildenafil: Back pain is a reported side effect of Sildenafil, which works by increasing blood flow and relaxing the blood vessels. The exact cause of back pain isn't fully understood, but it might be related to the increased blood flow and vascular effects in the body. For most people, back pain (if it occurs) is typically mild and goes away on its own after a short period. However, in rare cases, the back pain may be more persistent or severe. If you experience significant discomfort or the pain lasts longer than a few hours, you should contact your healthcare provider to rule out any serious issues.