When did your erectile dysfunction start? There are many factors to considering when shopping for health insurance including rate, coverage, HMO vs. Vardenafil usually works for 4 to 5 hours. If Viagra is not covered, you may want to check to see if similar drugs that help treat erectile dysfunction, like Cialis or Levitra, are covered by your health insurance plan. These small differences affect the way each medication works, such as how quickly it takes effect and wears off, and the possible side effects. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. If Viagra is covered by your insurance, the prescription co-pay is usually the same at all pharmacies, so there is no need to shop around for the best price.Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is . For more on diagnosing and treating ED, read What to do About Erectile Dysfunction, a Special Health Report from Harvard Medical School. If you’ve been having difficulty getting or sustaining erections, talk about it with your doctor. Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles .