Generic Name: Tadalafil (PAH)
Brand Name: Cialis

Treating high blood pressure in the lungs (pulmonary arterial hypertension [PAH]. It may also be used for other conditions as determined by your doctor.

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor. It works by relaxing and dilating the vessels in the lungs. This lowers the blood pressure in the lungs and helps to improve your ability to exercise.

Do NOT use Tadalafil if:

• you are allergic to any ingredient in Tadalafil
• you have severe kidney or liver problems, certain hereditary eye problems (eg, retinitis pigmentosa), or if you are on dialysis
• you have pulmonary veno-occlusive disease (PVOD)
• you take a nitrate (eg, isosorbide, nitroglycerin) in any form (eg, tablet, capsule, patch, spray, ointment), or nitroprusside
• you take another medicine that contains tadalafil, another PDE5 inhibitor (eg, sildenafil, vardenafil), an azole antifungal (eg, itraconazole, ketoconazole), or rifampin
• you use certain recreational drugs called “poppers” (eg, amyl nitrate or nitrite, butyl nitrate or nitrite)

Contact your doctor or health care provider right away if any of these apply to you.

Before using Tadalafil :

Some medical conditions may interact with Tadalafil . Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have a history of a prolonged (more than 4 hours) or painful erection (priapism)
• if you have a deformed penis (eg, Peyronie disease, cavernosal fibrosis), certain blood cell problems (eg, sickle cell anemia, leukemia, multiple myeloma), or other conditions that may increase the risk of a prolonged or painful erection (priapism)
• if you have low blood pressure, uncontrolled high blood pressure, blood vessel problems, angina (chest pain), heart problems (eg, heart valve disease, congestive heart failure, irregular heartbeat) or a history of these conditions
• if you have a history of heart attack, stroke, life-threatening irregular heartbeat, liver or kidney problems, dialysis, ulcers, or bleeding problems
• if you have a history of eye or vision problems (eg, decreased vision or vision loss, optic nerve problems, retina problems) or hearing problems (eg, ringing in the ears, decreased hearing, hearing loss)
• if you take medicine for erectile dysfunction (ED)

Some MEDICINES MAY INTERACT with Tadalafil . Tell your health care provider if you are taking any other medicines, especially any of the following:

• Alpha-blockers (eg, doxazosin), medicines for high blood pressure, or nitrates (eg, isosorbide, nitroglycerin) because severe low blood pressure with dizziness, lightheadedness, and fainting may occur
• Azole antifungals (eg, itraconazole, ketoconazole), HIV protease inhibitors (eg, ritonavir), macrolide antibiotics (eg, erythromycin), or telithromycin because they may increase the risk of Tadalafil ’s side effects
• Barbiturates (eg, phenobarbital), bosentan, carbamazepine, hydantoins (eg, phenytoin), or rifampin because they may decrease Tadalafil ’s effectiveness

This may not be a complete list of all interactions that may occur. Ask your health care provider if Tadalafil may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

Source: http://www.drugs.com/cdi/tadalafil.html