Cialis (tadalafil) and Viagra (sildenafil) are both prescription drugs used to treat erectile dysfunction (ED), but taking them together is generally not recommended. Mixing these medications can lead to dangerously low blood pressure and a higher risk of side effects. If you take tadalafil for pulmonary arterial hypertension, do not take Cialis® or other PDE5 inhibitors, including sildenafil (Revatio® or Viagra®) or vardenafil (Levitra®). A large study of nearly 74,000 men suggests that long-term use of tadalafil, best known as Cialis, may be linked to a higher risk of glaucoma and other eye pressure problems. Men prescribed the. Can you take Cialis in the morning and Viagra at night? Learn how these drugs work, why you shouldn't take both, and other ways to treat erectile dysfunction. Tadalafil (Cialis) is a medication used to treat erectile dysfunction. It’s also used to treat symptoms of benign prostatic hyperplasia. Tadalafil can interact with nitrates, riociguat (Adempas), and alpha blockers. Blood pressure medications and grapefruit can also interact with tadalafil. Combining Viagra and Cialis is a possible treatment option for some patients with erectile dysfunction, particularly when tadalafil alone is insufficient to achieve a satisfactory erection. You can take Cialis with or without food, but avoid combining it with grapefruit or alcohol. As with any medication, Cialis can also cause side effects, including headaches and indigestion. Find patient medical information for Tadalafil (Cialis, Adcirca, and others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Cialis (tadalafil) and Viagra (sildenafil) are both prescription drugs used to treat erectile dysfunction (ED), but taking them together is generally not recommended. Cialis is a popular ED medication. Find out everything you need to know about this doctor-prescribed medication including usage, effectiveness, safety considerations, and where to buy online.