Silagra 50 mg (Sildenafil) can sometimes cause back pain, but it is not very common.   Why it can happen Sildenafil works by relaxing blood vessels and affecting blood flow. In some people, this can lead to: Mild muscle aches Back pain (especially lower back) Body or joint pain This is related to how the drug affects smooth muscle and blood vessels, not a direct injury to the back.   How common is it? Less common than headache or flushing Usually mild to moderate More likely with higher doses (like 100 mg) than 50 mg   When it usually starts A few hours after taking the tablet Can last up to 12–24 hours in some case When to worry  Back pain is usually harmless, but get medical advice if: Pain is severe or worsening It comes with chest pain, breathlessness, or dizziness You also have muscle weakness or dark urine (very rare, could suggest a serious muscle reaction)  What can help Drink water and rest Light stretching or warm compress Avoid alcohol (can worsen side effects) If you want, I can also tell you how to reduce side effects of Silagra or whether switching to a lower dose or alternative medicine might help you.