Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. Viagra vs. You can take it in a small dose daily or in a larger dose as needed. Avanafil Stendra. Oral medicine for ED also might not be safe or work well if you have: Very low blood pressure, called hypotension, or uncontrolled high blood pressure, called hypertension. However, if you’d feel more comfortable talking with a healthcare provider virtually rather than in person, you can consider requesting an online ED prescription instead.Learn more about Cialis oral. 1. This is a generic drug. The average cost for 30 Tablet(s), 5mg each of the generic (tadalafil) is $ You can buy tadalafil at the discounted price of $ by using the MDRx coupon, a savings of 93%. Even if this drug is covered by Medicare or your insurance, we recommend you compare prices. Dosage. The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide.