However, others work on a cash-pay basis and don’t partner with insurance companies. 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. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The result of smooth muscle cell target protein phosphorylation is a decrease in intracellular calcium, increased efflux of potassium, and deactivation of myosin light chain kinase, ultimately causing smooth muscle relaxation. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher.For daily use, Goldstein said, the generic form, sildenafil, comes in mg tablets. “We prescribe one mg tablet a night, a classic dose,” he said. “Should they wish to have sex, they. Strengths: 25 mg, 50 mg, mg; Brand: Viagra. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Adult dosage (ages 18–64 years) Typical dosage: 50 mg, taken as needed about 1 hour before. swelling in your hands, ankles, or feet; shortness of breath; seizure (convulsions); or. a light-headed feeling, like you might pass out. Common Viagra side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; abnormal vision (blurred vision, changes in color vision) runny or stuffy nose, nosebleeds;.