###Human: How much dosage of Sildenafil is advisable for erectile dysfunction in a diabetic? ###Assistant: Hi. Erectile dysfunction can be due to many conditions including psychological and underlying like diabetes, hypertension, thyroid dysfunction, atherosclerotic disease and some medicine such as antipsychotic, some antihypertensives. So you need to be evaluated to find the cause of erectile dysfunction. Drug therapy includes Sildenafil, Tadalafil, Vardenafil, and injection Alprostadil can be used. These are prescription only drugs, so you need a prescription for the same. Sildenafil and related drug are contraindicated in a person taking nitrates. The starting dose of Sildenafil is 50 mg in most cases and depending upon the response the doses can be decreased or increased. It comes in 25, 50 and 100 mg dose. I would like to inform you that diabetes is one of the leading cause of erectile dysfunction and taking Sildenafil alone will offer temporary relief so you need to have good control of your diabetes.