Cialis relaxes muscles of the blood vessels and increases blood flow to particular areas of the body.

Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate).

Another brand of tadalafil is Adcirca, which is used to treat pulmonary arterial hypertension and improve exercise capacity in men and women. Do not take Cialis while also taking Adcirca, unless your doctor tells you to.

Do not take Cialis if you are also using a nitrate drug for chest pain or heart problems, including nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, and some recreational drugs such as "poppers". Taking tadalafil with a nitrate medicine can cause a sudden and serious decrease in blood pressure.

Some medicines can cause unwanted or dangerous effects when used with Cialis. Tell your doctor about all your current medicines, especially riociguat (Adempas).

Contact your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.

Get medical help at once if you have nausea, chest pain, or dizziness during sex.

Stop using Cialis and get emergency medical help if you have sudden vision loss.

Before taking this medicine

You should not take Cialis if you are allergic to tadalafil.

Taking Cialis with certain other medicines can cause a sudden and serious decrease in blood pressure. Do not take this medicine if you also use:

• riociguat (to treat pulmonary arterial hypertension); or

• a nitrate drug (for chest pain or heart problems) such as nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, or recreational drugs such as amyl nitrate or nitrite "poppers".

Some tadalafil can remain in your bloodstream for 2 or more days after each dose you take (longer if you have liver or kidney disease). Avoid nitrate use during this time.

To make sure this Cialis is safe for you, tell your doctor if you have ever had:

• heart disease or heart rhythm problems;

• a heart attack or stroke;

• angina (chest pain), high or low blood pressure;

• pulmonary hypertension (unless you are taking tadalafil for this);

• a condition called pulmonary veno-occlusive disease (narrowing of the veins that carry blood from the lungs to the heart);

• liver or kidney disease (or if you are on dialysis);

• vision loss, or retinitis pigmentosa (an inherited condition of the eye);

• a bleeding disorder;

• a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;

• a physical deformity of the penis (such as Peyronie's disease), or an erection lasting longer than 4 hours;

• a stomach ulcer; or

• health problems that make sexual activity unsafe.

Sudden vision loss has occurred in a small number of people taking medicines like tadalafil (Viagra or others). Most of these people already had certain eye problems or had high cholesterol, diabetes, coronary artery disease, a history of smoking, or were over 50 years old). It is not clear whether the medicine was the actual cause of vision loss.

Cialis is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether tadalafil passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

Cialis is not approved for use by anyone younger than 18 years old.

Cialis is usually taken only once per day. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Cialis can be taken with or without food.

Do not break or split a tablet. Swallow it whole.

For erectile dysfunction, take Cialis just before sexual activity but not more than once per day.

Cialis can help achieve an erection when sexual stimulation occurs. An erection will not occur just by taking a pill. Follow your doctor's instructions.

Do not take Cialis for erectile dysfunction if you are taking Adcirca for pulmonary arterial hypertension.

Store at room temperature away from moisture and heat.

You should not take Cialis if you are allergic to tadalafil.

Taking Cialis with certain other medicines can cause a sudden and serious decrease in blood pressure. Do not take this medicine if you also use:

• riociguat (to treat pulmonary arterial hypertension); or

• a nitrate drug (for chest pain or heart problems) such as nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, or recreational drugs such as amyl nitrate or nitrite "poppers".

Some tadalafil can remain in your bloodstream for 2 or more days after each dose you take (longer if you have liver or kidney disease). Avoid nitrate use during this time.

To make sure this Cialis is safe for you, tell your doctor if you have ever had:

• heart disease or heart rhythm problems;

• a heart attack or stroke;

• angina (chest pain), high or low blood pressure;

• pulmonary hypertension (unless you are taking tadalafil for this);

• a condition called pulmonary veno-occlusive disease (narrowing of the veins that carry blood from the lungs to the heart);

• liver or kidney disease (or if you are on dialysis);

• vision loss, or retinitis pigmentosa (an inherited condition of the eye);

• a bleeding disorder;

• a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;

• a physical deformity of the penis (such as Peyronie's disease), or an erection lasting longer than 4 hours;

• a stomach ulcer; or

• health problems that make sexual activity unsafe.

Sudden vision loss has occurred in a small number of people taking medicines like tadalafil (Viagra or others). Most of these people already had certain eye problems or had high cholesterol, diabetes, coronary artery disease, a history of smoking, or were over 50 years old). It is not clear whether the medicine was the actual cause of vision loss.

Cialis is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether tadalafil passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

Cialis is not approved for use by anyone younger than 18 years old.

As Cialis is used as needed, you are not likely to be on a dosing schedule.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Drinking alcohol with this medicine can cause side effects.

Grapefruit and grapefruit juice may interact with tadalafil and lead to unwanted side effects. Avoid the use of grapefruit products while taking this medicine.

Get emergency medical help if you have signs of an allergic reaction to Cialis: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop and get medical help at once if you have nausea, chest pain, or dizziness during sex. You could be having a life-threatening side effect.

Stop using this medicine and call your doctor at once if you have:

• a light-headed feeling, like you might pass out;

• an erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis);

• vision changes or sudden vision loss;

• ringing in your ears or sudden hearing loss; or

• heart attack symptoms - chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating.

Common Cialis side effects may include:

• headache;

• flushing (warmth, redness, or tingly feeling);

• nausea, upset stomach;

• stuffy nose; or

• muscle pain, back pain, pain in your arms, legs, or back.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• medicines to treat erectile dysfunction or pulmonary arterial hypertension;

• an antibiotic or antifungal medicine;

• antiviral medicine to treat hepatitis C or HIV/AIDS;

• drugs to treat high blood pressure or a prostate disorder; or

• seizure medicine.

This list is not complete. Other drugs may interact with tadalafil, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.