Cialis (Tadalafil) - Oral

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What Is Cialis? 

Cialis (tadalafil) is a prescription medication used to treat erectile dysfunction (ED). Erectile dysfunction is the inability to get or keep an erection long enough for sexual intercourse. Cialis also treats a condition called benign prostatic hypertrophy (BPH), known as enlarged prostate. BPH can cause many of the same symptoms as prostate cancer.

Cialis is a pill in the class of medications called PDE5 inhibitors. It works to relax the smooth muscles in the penis to allow for increased blood flow to the area.

Drug Facts

  • Generic Name: Tadalafil
  • Brand Name(s): Cialis, Adcirca, Alyq
  • Drug Availability: Prescription
  • Therapeutic Classification: Erectile dysfunction agent
  • Available Generically: Yes
  • Controlled Substance: N/A
  • Administration Route: Oral
  • Active Ingredient: Tadalafil
  • Dosage Form: Tablet

What Is Cialis Used For?

The Food and Drug Administration (FDA) has approved Cialis to treat ED, the signs and symptoms of BPH, and symptoms of combined ED and BPH.

Tadalafil is also approved under the brand name Adcirca for pulmonary arterial hypertension, a condition in which the blood pressure inside the pulmonary artery is too high.

How to Take Cialis

Dosing instructions may differ for ED, BPH, and combined ED and BPH.

For once-daily dosing, take Cialis at around the same time every day, with or without food. Take the tablets whole; do not split them.

Storage

Store Cialis at room temperature and keep the medication out of children’s reach.

How Long Does Cialis Take to Work?

When using as needed, you may be able to have sexual activity at least 30 minutes after taking Cialis and up to 36 hours after taking it.

What Are the Side Effects of Cialis?

This is not a complete list of side effects, and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 1-800-FDA-1088.

As with most medications, Cialis has the potential to cause side effects. 

Common Side Effects

The most common side effects associated with Cialis include:

  • Headache
  • Heartburn
  • Back pain
  • Flushing
  • Upper respiratory infection
  • Nasal congestion (stuffy nose)
  • Muscle aches

Severe Side Effects

Serious side effects and their symptoms can include the following:

  • Prolonged erection (greater than four hours)
  • Sudden loss of vision
  • Other vision changes
  • Sudden hearing loss
  • Ringing in the ears
  • Chest pain
  • Shortness of breath

Contact your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

Report Side Effects

Cialis may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting Program or by phone (1-800-332-1088).

Dosage: How Much Tadalafil Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.


For oral dosage form (tablets):

For treatment of benign prostatic hyperplasia (daily use):

  • Adults—5 milligrams (mg) as a single dose, no more than once a day, taken at the same time each day.
  • Children—Use is not recommended.

For treatment of erectile dysfunction (as needed):

  • Adults—10 milligrams (mg) as a single dose, no more than once a day, taken 30 minutes before you think sexual activity may occur. Your doctor may adjust your dose as needed.
  • Children—Use is not recommended.

For treatment of erectile dysfunction (daily use):

  • Adults—2.5 milligrams (mg) once a day, taken at the same time each day, without regard for the timing of sexual activity. Your doctor may adjust your dose as needed.
  • Children—Use is not recommended.

For treatment of erectile dysfunction and benign prostatic hyperplasia (daily use):

  • Adults—5 milligrams (mg) once a day, taken at the same time each day, without regard for the timing of sexual activity.
  • Children—Use is not recommended.

For treatment of pulmonary arterial hypertension:

  • Adults—40 milligrams (mg) (two 20 mg tablets) taken once a day. Take both tablets at the same time each day. Do not divide the 40 mg dose. Your doctor may adjust your dose as needed.
  • Children—Use and dose must be determined by your doctor.

Modifications 

Your provider may adjust your dose if you have mild or moderate kidney or liver disease. Cialis is not recommended for use in patients with severe liver impairment.

Patients with a creatinine clearance of 30 to 50 milliliters per minute (mL/min) may also need a dosage adjustment. Patients with a creatinine clearance of less than 30 mL/min or on hemodialysis can use Cialis as needed. However, the dose should not exceed 5 milligrams (mg) every 72 hours, and once-daily use is not recommended.

Missed Dose 

If you use Cialis daily and a dose is missed, you can take it as soon as you remember, as long as it is not on the same day as the next dose. Never double up on doses.

Overdose: What Happens If I Take Too Much Cialis?

Symptoms experienced with an overdose of Cialis may have side effects similar to the normal dose.

What Happens If I Overdose on Cialis?

If you think you or someone else may have overdosed on Cialis (tadalafil), call your healthcare provider or the Poison Control Center at 1-800-222-1222.

If someone collapses or isn't breathing after taking tadalafil, call 911 immediately.

Precautions

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It is important that you tell all of your doctors that you take tadalafil. If you need emergency medical care for a heart problem, it is important that your doctor knows when you last took tadalafil.

If you will be taking this medicine for pulmonary arterial hypertension, it is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood and urine tests may be needed to check for unwanted effects.

If you take tadalafil for pulmonary arterial hypertension, do not take Cialis® or other PDE5 inhibitors, such as sildenafil (Revatio® or Viagra®) or vardenafil (Levitra®). Cialis® also contains tadalafil. If you take too much tadalafil or take it together with these medicines, the chance for side effects will be higher.

If you experience a prolonged erection for more than 4 hours or a painful erection for more than 6 hours, contact your doctor immediately. This condition may require prompt medical treatment to prevent serious and permanent damage to your penis.

This medicine does not protect you against sexually transmitted diseases (including HIV or AIDS). Use protective measures and ask your doctor if you have any questions about this.

It is important to tell your doctor about any heart problems you have now or may have had in the past. This medicine can cause serious side effects in patients with heart problems.

Do not use this medicine if you are also using riociguat or a nitrate medicine, often used to treat angina (chest pain). Nitrate medicines include nitroglycerin, isosorbide, Imdur®, Nitro-Bid®, Nitrostat®, Nitro-Dur®, Transderm Nitro®, Nitrol® Ointment, and Nitrolingual® Spray. Some illegal ("street") drugs called "poppers" (such as amyl nitrate, butyl nitrate, or nitrite) also contain nitrates. If you need to use a nitrate medicine, take it at least 48 hours after your last dose of tadalafil.

Do not drink excessive amounts of alcohol (eg, 5 or more glasses of wine or 5 or more shots of whiskey) when taking tadalafil. When taken in excess, alcohol can increase your chances of getting a headache or dizziness, increase your heart rate, or lower your blood pressure.

If you experience sudden loss of vision in one or both eyes, contact your doctor immediately.

Check with your doctor right away if you have a sudden decrease in hearing or loss of hearing, which may be accompanied by dizziness and ringing in the ears.

Do not eat grapefruit or drink grapefruit juice while you are using this medicine. Grapefruit and grapefruit juice may change the amount of this medicine that is absorbed in the body.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Cialis?

Cialis should not be taken if certain heart problems are present, such as:

  • Angina (chest pain)
  • Aortic stenosis
  • Heart attack within previous three months
  • Heart failure, also known as congestive heart failure
  • Uncontrolled high blood pressure
  • Stroke in the previous six months
  • Intolerance of sexual activity

What Other Medications Interact With Cialis? 

Multiple medications may interact with Cialis when taken together. If you are taking any of these medications, use them with caution and only under the direction of your healthcare provider. 

When taken together, Cialis may increase the blood pressure–lowering effects of:

  • Nitrates: nitroglycerin, isosorbide mononitrate, isosorbide dinitrate
  • Blood pressure medications: amlodipine, angiotensin receptor blockers, metoprolol
  • Alpha-blockers: doxazosin, tamsulosin, alfuzosin

Other drugs can affect the way Cialis works. For example, magnesium hydroxide/aluminum hydroxide–containing antacids (Maalox) may slow the absorption of tadalafil.

The following medications may increase the side effects experienced with Cialis:

  • HIV protease inhibitors: ritonavir
  • Some types of oral antifungals, such as ketoconazole and itraconazole
  • Some types of antibiotics, such as clarithromycin, telithromycin, and erythromycin

What Medications Are Similar? 

There are other medications that work similarly to Cialis. 

These medications include:

The above medications are in the class of PDE5 inhibitors and work in the same way. They should not be used together. Tadalafil is also available under other brand names including Adcirca and Alyq. These medications should not be taken with Cialis. 

Frequently Asked Questions

  • What is Cialis used for?

    Cialis is used to treat erectile dysfunction, benign prostatic hypertrophy, and erectile dysfunction with benign prostatic hypertrophy.

  • What drugs should not be taken with Cialis?

    Cialis has interactions with many medications, including nitrates for chest pain, blood pressure medications, antacids, and medications in the class of alpha-blockers.

  • What are the side effects of Cialis?

    The most common side effects of Cialis include headaches, back pain, nasal congestion (stuffy nose), upper respiratory infection, and flushing. More severe side effects include prolonged erection, sudden loss of vision, and sudden loss of hearing.

  • How does Cialis work?

    Cialis works by relaxing the smooth muscle inside the blood vessels of the penis to allow for increased blood flow. The increased blood flow can make it easier to have an erection.

How Can I Stay Healthy While Taking Cialis?

Cialis can be an effective medication to treat ED and BPH. However, it should not be taken without discussion with your healthcare provider about any risks or other medications you may be taking. Reach out to your healthcare team if you experience any side effects or have concerns about the medication.

Medical Disclaimer

Verywell Health's drug information is meant for education purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

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  1. Food and Drug Administration. Cialis label. Updated February 2018.

  2. Murphy M, Demers JM, Ostroff ML, Ostroff JL. Oral PDE5 inhibitors for erectile dysfunction. US Pharm. 2018;43(6):29-33.