Tadalafil belongs to a group of medications called phosphodiesterase type 5 inhibitors. It is used for the treatment of erectile dysfunction (male impotence). It helps to achieve and maintain an erection when sexual stimulation occurs. It does this by allowing a greater flow of blood into the penis when a man taking the medication is sexually aroused. It works only with sexual stimulation and does not increase sexual desire.

Your doctor may have suggested this medication for conditions other than the ones 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.

The usual recommended dose is one 20 mg tablet taken as needed, at least 30 minutes before sexual activity. This medication has been shown to be effective within 30 minutes of taking the tablet, and up to 36 hours later. As the amount of time tadalafil takes to work varies from person to person, initiating sexual activity at different times after taking the tablet will determine the optimal time for sexual activity. The maximum recommended amount of medication to take is one tablet a day.

Tadalafil may be taken with or without food.

Many things can affect the dose of 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 given here, do not change the way that you are taking the medication without consulting your doctor.

It is very important that this medication be taken exactly as prescribed by the doctor. Do not take higher doses of this medication than prescribed by your doctor.

Keep this medication out of reach and sight of children. This medication should be stored at room temperature, between 15°C and 30°C.

Cialis® is available as tablets in strengths of 10 mg and 20 mg.

10 mg: Each yellow, almond-shaped, film-coated tablet, marked "C10" on one side, contains 10 mg of tadalafil.

20 mg: Each yellow, almond-shaped, film-coated tablet, marked "C20" on one side, contains 20 mg of tadalafil.

Nonmedicinal ingredients: croscarmellose sodium, hydroxypropyl cellulose, hydroxypropyl methylcellulose, iron oxide, lactose monohydrate, magnesium stearate, microcrystalline cellulose, sodium lauryl sulfate, talc, titanium dioxide, and triacetin.

This medication contains a small amount of lactose (about 250 mg) which is unlikely to affect men who might have lactose intolerance.

Tadalafil should not be taken by anyone who:

• is taking any type of nitrate medication in any form (oral, sublingual [under the tongue], skin patch, or spray). Nitrate medications include nitroglycerin and related medicines that are used for the relief of chest pain or angina. They also include amyl nitrate ("poppers"). Use of these medications with tadalafil could cause a sudden severe drop in blood pressure that could lead to dizziness, fainting, heart attack, or stroke.
• has been advised by their doctor not to engage in sexual activity
• is allergic to tadalafil or any of the ingredients of the medication

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. Your health professional may be able to help you to deal with some of the effects.

The following side effects may go away as your body becomes used to the medication; check with your doctor if the following side effects continue or become bothersome.

Common
• headache
• back pain
• facial flushing
• indigestion or stomach discomfort following meals
• muscle ache
• nasal congestion

Rare
• swelling of the eyelids
• dizziness

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

Rare
• prolonged (longer than four hours), painful, or inappropriate erection of penis (priapism)
• sudden dizziness, feeling faint

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.

Alcohol: Consumption of alcohol in large amounts may decrease the ability to attain the erection and may also temporarily decrease blood pressure causing dizziness and fainting.

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 drugs.

Heart condition: Men who have or have had heart disease or a heart attack or stroke, should seek their doctor's approval before taking any medication for erectile dysfunction. If chest pains, dizziness, or nausea is experienced during sex, the exertion should be stopped and the doctor informed.

Kidney problems: Lower doses of this medication should be used in individuals with impaired kidney function. Daily use of this medication is not recommended.

Liver problems: No clinical studies have taken place on the use of this medication by men with severe liver disease; therefore the use of tadalafil is not recommended for these individuals.

Nitrate-containing medications: Tadalafil should never be taken with any medications that contain nitrates. There is a risk of sudden blood pressure drop to life-threatening levels if tadalafil is taken with any nitrate-containing medication (e.g., nitroglycerin tablets, spray, patches, or isosorbide dinitrate) or any other nitrates (e.g., amyl nitrite "poppers"). You could experience dizziness, fainting spells, or have a heart attack or stroke. If use of a nitrate-containing medication is considered medically necessary, 48 hours must pass after the last dose of tadalafil before taking a nitrate, and only under close medical supervision.

Penis deformation: As with other agents used for the treatment of erectile dysfunction, tadalafil should be used with caution by men with an anatomical deformation of the penis such as angulation, cavernosal fibrosis, or Peyronie's disease.

Prolonged erection: If an erection lasts longer than four hours (a rare occurrence), seek immediate medical assistance. If this condition is not treated quickly, tissue damage and permanent loss of potency could result. Tadalafil should be used with caution in men who have conditions that might predispose them to prolonged erection such as sickle cell anemia, multiple myeloma, or leukemia.

Prostate problems: Tell your doctor if you are taking medications to treat prostate problems such as alpha blockers (e.g., doxazosin) as the combination of these medications with tadalafil may add to the blood-pressure-lowering effect of these drugs.

Children and adolescents: Tadalafil is not intended for use by children or adolescents under the age of 18.

Pregnancy and breast-feeding: Tadalafil is not intended for use by women.

The following medications may affect the way that tadalafil works or increase the risk of side effects:

• antacids (magnesium hydroxide, aluminum hydroxide)
• erythromycin
• itraconazole
• ketoconazole
• nitrates (e.g., nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate)
• protease inhibitors (e.g., indinavir, nelfinavir, ritonavir, saquinavir)
• rifampin
• theophylline

Grapefruit juice may increase the amounts of tadalafil in the blood.

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. In many cases, interactions are intended or are managed by close monitoring. 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 that 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.