DHEA appears to be safe at low doses. Also collected as part of the IIEF was information about other aspects of sexual function, including information on erectile function, orgasm, desire, satisfaction with intercourse, and overall sexual satisfaction. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. It appears to be safe used on a short-term basis. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. If you are taking sildenafil for erectile dysfunction, your doctor will probably start you on an average dose of sildenafil and increase or decrease your dose depending on your response to the medication. This site is intended only for U.In , a meta-analysis of trials determined that while Viagra is the most effective of the various ED drugs on the market, it also has the highest incidence of side effects—headache, upset stomach, vision loss, blue-tinged sight, back pain, muscle pain, nausea, and dizziness, just to name a few common ones. Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the . 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.