Xie Aili is the trade name, the generic name is tadalafil tablets, Van Eck is the trade name of sildenafil tablets, both of them can treat erectile dysfunction, the difference is in the duration of efficacy, precautions, adverse reactions and so on. 1. Duration: Tadalafil lasts longer, usually up to 36 hours; while sildenafil lasts shorter, around 4 hours, you need to take the drug according to the actual need. 2. Precautions: Tadalafil is generally less affected by a fatty diet; sildenafil absorption will be affected by a high-fat diet, which will lead to slower absorption. 3. Adverse reactions: tadalafil adverse reactions are relatively mild compared to sildenafil, there will be a transient headache, back pain, dyspepsia and so on. But sildenafil adverse reactions will be more serious compared to tadalafil, there may be photosensitivity, color blindness, blurred vision and so on. Both the drugs should not be used in women, children, and newborns. Taking these two medications requires a doctor’s guidance.