Do not take it more than 3 times a day. Use protective measures and ask your doctor if you have any questions about this. The dose can be increased to mg or decreased to 25mg depending on its effect. This medicine comes with a patient information leaflet. ED is associated with depression, anxiety, and loss of self-esteem.Available strengths: 25 mg, 50 mg, mg. 25 milligram (mg), 50 mg, and mg. Other forms of sildenafil (the active drug in Viagra) comes in other strengths, such as 20 mg. But Viagra only. Sildenafil tablets for erectile dysfunction come in different strengths ranging from 25mg to mg. The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex. Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online .