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

Tadalafil under the name of 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 tadalafil 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 tadalafil. 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 tadalafil and get emergency medical help if you have sudden vision loss.

Before taking this medicine

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

Taking tadalafil 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 medicine 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 risk factors for blood vessel disorders (heart disease, diabetes, high blood pressure, high cholesterol, coronary artery disease, smoking, or being over 50 years old). It is not clear whether the medicine was the actual cause of vision loss. Sudden hearing loss has also been reported with tadalafil. Stop tadalafil and call your doctor immediately for any hearing loss, decrease in hearing, or ringing in the ears.

Do not start or stop taking tadalafil during pregnancy without your doctor's advice. Having pulmonary arterial hypertension (PAH) during pregnancy may cause heart failure, stroke, or other medical problems in both mother and baby. Tell your doctor right away if you become pregnant.

It may not be safe to breastfeed while using tadalafil. Ask your doctor about any risk.

Cialis is not for use in women.

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

Tadalafil comes as a tablet to take by mouth. It may be taken with or without food.

If you are taking tadalafil to treat erectile dysfunction, follow your doctor's directions and the guidelines in this paragraph. There are two different ways to take tadalafil, either daily or on an as needed basis. Talk to your doctor about which dosing schedule is right for you. Tadalafil is sometimes taken as needed, usually at least 30 minutes before sexual activity and not more often than once every 24 hours. Your doctor will help you decide the best time for you to take tadalafil before sexual activity. Tadalafil is also sometimes taken once a day every day without regard to timing of sexual activity. You may attempt sexual activity at any time between doses. If you are taking tadalafil on a regular schedule, take it at around the same time every day. If you have certain health conditions or are taking certain medications, your doctor may tell you to take tadalafil less often or may prescribe a lower dose to be taken once a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take tadalafil exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you are taking tadalafil to treat PAH or BPH, follow your doctor's directions and the guidelines in this paragraph. You should take tadalafil one time a day. Take all of the tablets for your daily dose at one time each day; do not divide the tablets to take as separate doses. Take tadalafil at around the same time every day. If you are already taking medication to treat BPH, your doctor may tell you to stop taking your other medication at least one day before starting treatment with tadalafil. Follow your doctor's directions carefully, and ask your doctor or pharmacist to explain any part you do not understand.

If you are taking tadalafil for erectile dysfunction, your doctor will probably start you on an average dose of tadalafil and increase or decrease your dose depending on your response to the medication. Tell your doctor if tadalafil is not working well or if you are experiencing side effects.

If you are taking tadalafil for PAH, you should know that tadalafil controls PAH but does not cure it. Continue to take tadalafil even if you feel well. Do not stop taking tadalafil without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Tadalafil 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.

Tadalafil can be taken with or without food.

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

For erectile dysfunction, take Cialis just before sexual activity but not more than once per day. It can be used up to 36 hours before sexual activity. 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 tadalafil if you are allergic to it.

Taking tadalafil 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 medicine 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 risk factors for blood vessel disorders (heart disease, diabetes, high blood pressure, high cholesterol, coronary artery disease, smoking, or being over 50 years old). It is not clear whether the medicine was the actual cause of vision loss. Sudden hearing loss has also been reported with tadalafil. Stop tadalafil and call your doctor immediately for any hearing loss, decrease in hearing, or ringing in the ears.

Do not start or stop taking tadalafil during pregnancy without your doctor's advice. Having pulmonary arterial hypertension (PAH) during pregnancy may cause heart failure, stroke, or other medical problems in both mother and baby. Tell your doctor right away if you become pregnant.

It may not be safe to breastfeed while using tadalafil. Ask your doctor about any risk.

Cialis is not for use in women.

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

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

If you take tadalafil every day and you miss a dose, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

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

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine.

Drinking alcohol with this medicine can cause a drop in blood pressure, leading to dizziness or fainting.

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 tadalafil: 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 tadalafil 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 tadalafil 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.

Keep all appointments with your doctor.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.