How does this medication work? What will it do for me?

Tadalafil belongs to the group of medications known as phosphodiesterase type 5 inhibitors. It is used to treat pulmonary hypertension (high blood pressure in the blood vessels of the lungs). It helps lower pulmonary blood pressure by relaxing and widening blood vessels, allowing blood to flow more easily to the lungs.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each orange, almond-shaped, biconvex, film-coated tablet, engraved "APO" on one side and "T20" on the other side, contains 20 mg of tadalafil. Nonmedicinal ingredients: lactose monohydrate, croscarmellose sodium, ferric oxide red, ferric oxide yellow, microcrystalline cellulose, sodium lauryl sulphate, poloxamer, magnesium stearate, hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyethylene glycol, and titanium dioxide.

How should I use this medication?

The usual recommended dose of tadalafil for pulmonary hypertension is 40 mg taken once daily. It can be taken with or without food.

For people with decreased kidney or liver function, a lower initial dose is recommended.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to tadalafil or to any of the ingredients of the medication
  • are taking nitroglycerin (sprays, ointments, skin patches or pastes, tablets) or other nitrate medications (e.g., isosorbide dinitrate or isosorbide mononitrate), due to the risk of developing dangerously low blood pressure

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • arm or leg pain
  • back pain
  • constipation
  • diarrhea
  • difficulty sleeping
  • fatigue
  • flushing
  • headache
  • heartburn
  • indigestion
  • muscle aches
  • nausea
  • reflux
  • stuffy nose
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • heavy menstrual bleeding
  • prolonged erection
  • stomach pain
  • symptoms of a urinary tract infection (e.g., pain or burning when urinating, frequent urge to urinate, cloudy-looking or foul-smelling urine)
  • symptoms of an upper respiratory tract infection (e.g., cough, sore throat, runny nose, fever, headache)
  • swelling of the feet, ankles, or hands
  • temporary memory loss

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • chest pain
  • shortness of breath
  • sudden decrease or loss of hearing or other hearing changes
  • sudden decrease or loss of vision or other vision changes
  • symptoms of a serious allergic reaction (such as swelling of the face, lips, tongue, or throat; skin rash; hives; or difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood conditions: Before taking this medication, tell your doctor if you have sickle cell anemia or leukemia.

Blood pressure: Tell your doctor if you are taking medications to treat high blood pressure, as the combination of these medications with tadalafil may add to the blood-pressure-lowering effect of these medications.

Dehydration: If you lose a large amount of body fluids (dehydration) through excessive sweating; from not drinking enough fluids; or from being sick with a fever, vomiting, or diarrhea, contact your doctor. Dehydration can make you more likely to experience low blood pressure while you are taking this medication.

Grapefruit juice: Grapefruit juice can increase the amount of tadalafil in your bloodstream. Talk to your doctor about drinking grapefruit juice when taking this medication.

Hearing changes: If you experience a decrease or loss of hearing while taking this medication, seek immediate medical attention.

Heart problems: If you have heart disease or other heart problems, you may be more likely to experience low blood pressure while taking this medication and should discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: If you have decreased kidney function, you may require a lower dose of this medication. Talk to your doctor. If you have severely reduced kidney function, you should not take this medication.

Liver function: If you have decreased liver function, you may require a lower dose of this medication. Talk to your doctor. People with severely reduced liver function should not take this medication.

Lung problems: Tadalafil is not recommended for people with a form of high blood pressure in the lungs called pulmonary veno-occlusive disease. If you have pulmonary veno-occlusive disease or experience sudden cough, shortness of breath, chest pain, or rapid breathing, talk to your doctor before taking this medication.

Nitrate-containing medications: Never take tadalafil with any medications that contain nitrates. Your blood pressure may suddenly drop to life-threatening levels if you take it with any nitrate-containing medication (e.g., nitroglycerin tablets, spray, or patches) or any other nitrates (e.g., isosorbide dinitrate or amyl nitrite "poppers"). You may experience dizziness, fainting spells, heart attack, or stroke.

Penis deformation: If you have a deformation of the penis such as angulation, cavernosal fibrosis, or Peyronie's disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Prolonged erection: Before taking this medication, tell your doctor if you have ever had an erection that lasted longer than 4 hours.

Vision problems: If you have or have had a temporary decrease or permanent loss of vision in one or both eyes, including a condition called non-arteritic anterior ischemic optic neuropathy (NAION), or if you have a condition called retinitis pigmentosa, tell your doctor before taking this medication.

This medication can cause partial or complete vision loss that may be temporary or permanent. If you experience a sudden loss of vision in one or both eyes or other vision related problems, tell your doctor immediately. If you do experience vision changes, do not drive or operate machinery until your vision returns to normal.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if tadalafil passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children with pulmonary hypertension.

What other drugs could interact with this medication?

There may be an interaction between tadalafil and any of the following:

  • alprostadil
  • boceprevir
  • carbamazepine
  • certain HIV medications (e.g., indinavir, nelfinavir, ritonavir, saquinavir)
  • certain medications for the treatment of prostate problems (e.g., doxazosin, prazosin)
  • clarithromycin
  • erythromycin
  • itraconazole
  • ketoconazole
  • medications that lower blood pressure (e.g., amlodipine, candesartan, valsartan, enalapril, metoprolol)
  • medications similar to tadalafil (e.g., sildenafil, vardenafil)
  • mifepristone
  • nitrates (e.g., nitroglycerin, isosorbide mononitrate, isosorbide dinitrate, or amyl nitrite "poppers")
  • phenobarbital
  • phenytoin
  • posaconazole
  • rifampin
  • telaprevir
  • voriconazole

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.