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Cialis dosage, forms, and strengths

Cialis forms and strengths | Cialis for adult males | ED | BPH | Cialis dosage restrictions | Cialis for pets | How to take Cialis | FAQs

Cialis is a brand-name prescription medication that treats erectile dysfunction (ED) or the signs and symptoms of benign prostatic hyperplasia (BPH), more commonly known as “prostate enlargement.” Tadalafil, the generic name for Cialis, belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. It works by dilating arteries in the penis, increasing and prolonging blood into erectile tissues in the penis. Tadalafil also relaxes smooth muscles in the bladder and the rest of the urinary tract, helping to alleviate the lower urinary tract symptoms (LUTS) experienced with BPH. Cialis doses will vary depending on the condition being treated. 

RELATED: Learn more about Cialis | Get Cialis discounts

Cialis forms and strengths

Cialis is available as a tablet in four different dose strengths—any of which can be taken with or without food.

  • Tablet: 2.5 milligrams (mg), 5 mg, 10 mg, and 20 mg

Cialis dosage for adult males

Cialis can be taken daily for erectile dysfunction or BPH. It can also be taken when needed for erectile dysfunction. Doses may vary.

  • Standard Cialis dosage for adults: 2.5-5 mg once per day or 5-20 mg as needed
  • Maximum Cialis dosage for adults: No more than 20 mg per day

Cialis dosage chart

Indication Starting dosage Standard dosage Maximum dosage
Erectile dysfunction (as needed) 10 mg taken before sexual activity 5-20 mg taken before sexual activity No more than 20 mg per day
Erectile dysfunction (once daily) 2.5 mg once per day 2.5-5 mg once per day 5 mg once per day
Benign prostatic hyperplasia with or without erectile dysfunction 5 mg once per day 5 mg once per day Not specified

Source: Epocrates

As-needed dosage for erectile dysfunction

Cialis is indicated to treat erectile dysfunction on an as-needed basis before anticipated sexual activity.

  • Adult males (18 years and older): 5-20 mg taken before anticipated sexual activity
  • Renally impaired patients (kidney disease)—dose amount adjustment: 
    • Creatinine clearance of 30-50 milliliters (ml)/min: 5-10 mg to a maximum of 10 mg every 48 hours
    • Creatinine clearance less than 30 ml/min: 5 mg every 72 hours
    • Hemodialysis: 5 mg every 72 hours, no supplement after dialysis
    • Parenteral dialysis: Not defined
  • Hepatically impaired patients (liver disease)—dose amount adjustment
    • Mild to moderate hepatic impairment: 5-10 mg to a maximum of 10 mg every 24 hours
    • Severe hepatic impairment: Not recommended

Daily dosage for erectile dysfunction

Cialis is approved for daily use to treat erectile dysfunction.

  • Adult males (18 years and older): 2.5-5 mg taken once per day
  • Renally impaired patients (kidney disease)
    • Creatinine clearance less than 30 ml/min: Not recommended
    • Hemodialysis: Not recommended
    • Parenteral dialysis: Not defined
  • Hepatically impaired patients (liver disease)
    • Mild to moderate hepatic impairment: Use with caution
    • Severe hepatic impairment: Not recommended

Daily dosage for symptoms of benign prostatic hyperplasia (BPH)

Cialis is taken to treat the lower urinary tract symptoms of benign prostatic hyperplasia. Therapy may start by combining Cialis with finasteride, another drug that treats lower urinary tract symptoms of BPH. Because BPH is sometimes associated with erectile dysfunction, a once-daily dose of Cialis can be taken to relieve both BPH symptoms and erectile problems (BPH/ED).

  • Adult males (18 years and older): 5 mg taken once per day
  • Renally impaired patients (kidney disease)—dose amount adjustment: 
    • Creatinine clearance of 30-50 ml/min: 2.5-5 mg once per day
    • Creatinine clearance less than 30 ml/min: Not recommended
    • Hemodialysis: Not recommended
    • Parenteral dialysis: Not defined
  • Hepatically impaired patients (liver disease)
    • Mild to moderate hepatic impairment: Use with caution
    • Severe hepatic impairment: Not recommended

Cialis dosage restrictions

Cialis is not approved for use in children younger than 18. It is also not approved for females.

Cialis dosage for pets

Cialis is not approved for use in animals. Giving Cialis or any other human medication to an animal can be hazardous to the animal even if the active ingredient is commonly prescribed to pets. Tadalafil, the active ingredient in Cialis, is sometimes used off-label in dogs. It is not, however, approved by the FDA for use in animals. As in humans, veterinarians use tadalafil to treat pulmonary hypertension, which is high pressure in the vessels that deliver blood to the lungs. Because research on tadalafil in animals is limited and its use is not approved, no standard or agreed-upon dosage has been determined. The dose and schedule will vary by practitioner. 

How to take Cialis

Cialis is taken as a tablet by mouth either once per day or as needed before sexual activity. To maximize safety and effectiveness, consider a few useful rules-of-thumb when taking Cialis:

  • Only take Cialis with a prescription and under the care of a healthcare provider.
  • Inform your healthcare provider about all medical conditions before starting Cialis.
  • When taking Cialis as needed, take it at least 30 minutes before sexual activity.
  • Do not take more than one dose per day or as directed by a healthcare provider.
  • Swallow the tablet whole. Do not crush or chew it.
  • This medicine includes a medication guide or patient information. A doctor, pharmacist, or healthcare provider can answer any questions you may have.
  • Always check the expiration date before taking Cialis or any other prescription medicine. If the tablets have passed their expiration date, dispose of them safely and get a new prescription.
  • Keep Cialis at room temperature (59-86 degrees Fahrenheit).
  • For once-a-day Cialis, try to schedule the daily dose at the same time each day.
  • For erectile dysfunction, sexual activity can be initiated any time from 30 minutes to 36 hours after taking Cialis.
  • For erectile dysfunction, sexual stimulation is required for Cialis to show benefits.
  • Do not use other erectile dysfunction medications, prescription nitrates such as nitroglycerin, or over-the-counter remedies such as nitrites (“poppers”).
  • Do not drink too much alcohol when taking Cialis. Avoid drinking five or more glasses of wine or shots of strong liquor, but some people will also experience side effects with lower amounts of alcohol.
  • Seek medical attention if you take too much Cialis; if you have chest pain, dizziness, or nausea during sex; or if you have an erection that lasts more than four hours. This is a rare side effect but can cause permanent damage if not treated.
  • Taking Cialis does not prevent sexually transmitted diseases.
  • Keep Cialis out of the reach of children.

Cialis dosage FAQs

How long does it take Cialis to work?

Cialis is absorbed quickly by the body and hits maximum concentration in the blood within 30 minutes to six hours after being taken, but usually around two hours. When taken as needed, the manufacturer suggests taking Cialis at least 30 minutes before any anticipated sexual activity, but some health sites suggest one or two hours. Taken as a daily dose, Cialis reaches a steady-state concentration in the blood after five days. Sexual activity can be engaged in at any time between doses. 

How long does Cialis stay in your system?

Tadalafil is sometimes nicknamed “the weekend pill” because its effects can last as long as 36 hours, considerably longer than similar PDE5 inhibitors. When healthcare professionals talk about how long a drug works, they use the drug’s half-life. This is the average amount of time it takes for a human body to metabolize half the dose that’s been taken. The half-life for tadalafil is 17.5 hours in healthy people. At that rate, depending on the size of the dose, tadalafil falls to undetectable levels in about four days.

What happens if I miss a dose of Cialis?

A missed dose can be taken when remembered. However, no more than one dose should be taken in a single day. Keep in mind that some people with kidney or liver problems may be on a more restricted dosing schedule. In those cases, talk to a doctor, pharmacist, or another qualified healthcare provider about how to handle a missed dose.

How do I stop taking Cialis?

You can stop Cialis at any time without tapering the dose but always talk to a healthcare provider before stopping Cialis. The good news is that Cialis does not cause physical dependence or withdrawal when used as directed. A significant fraction of men taking Cialis will notice an improvement in sexual function in the weeks after stopping Cialis.

Stop using Cialis and get emergency medical care if experiencing any of the following while taking the drug:

  • Sudden loss of vision in one or both eyes
  • Sudden hearing loss, sometimes accompanied by ringing in the ears and dizziness
  • Signs of an allergic reaction such as rash, hives, swelling, or difficulty breathing
  • Priapism, which is an erection that lasts more than four hours
  • Chest pain, nausea, or dizziness during sex

What is the maximum dosage for Cialis?

The maximum dose for Cialis is 20 mg per day. However, men should only take the prescribed dose once per day. Do not take a second dose the same day as the first. Some people with medical conditions such as liver or kidney problems will require a lower maximum dose, so consult with a doctor or other qualified healthcare provider.

What interacts with Cialis?

Grapefruit

Food does not affect the body’s absorption of Cialis, so feel free to take the medicine with or without food. Grapefruit, however, should be avoided. Grapefruit and grapefruit juice have substances that slow down the body’s metabolism of tadalafil. As a result, eating grapefruit and taking Cialis results in more tadalafil in the bloodstream and it stays in the blood for a longer time, raising the risk of side effects.

Alcohol

Drinking too much alcohol is also a bad idea. Both alcohol and Cialis lower blood pressure. Too much to drink combined with Cialis could cause a serious and health-threatening drop in blood pressure.

Other ED pills

For the same reason, tadalafil doesn’t mix well with other medications that lower blood pressure. In particular, tadalafil can cause dangerously low blood pressure when taken with other erectile dysfunction medications such as Viagra (sildenafil) or Levitra (vardenafil). Many ED medications are also prescribed for pulmonary arterial hypertension, which is high pressure in the arteries that send blood to the lungs. For instance, Cialis (tadalafil) is prescribed under the brand name Adcirca when used for pulmonary arterial hypertension, and Viagra (sildenafil) used for pulmonary hypertension is called Revatio

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Other medications that affect blood pressure

Low blood pressure is also the reason tadalafil is never used with nitrates, which are available as tablets, sprays, or patches for some heart conditions; some pulmonary arterial hypertension medications (guanylate cyclase stimulators such as riociguat); or alpha-blockers, a type of drug that treats either blood pressure (doxazosin and others) or an enlarged prostate (tamsulosin and others). 

All blood pressure medications may add to the blood pressure-reducing effects of tadalafil. It may be surprising to find that some other drugs and supplements may lower blood pressure, like garlic supplements, antidepressants, opioid pain relievers, and antipsychotics. There’s no rule against combining any of these with Cialis, but blood pressure will need to be watched. 

These CYP3A4 inhibitor drugs could increase the risk of interactions with Cialis:

  • Supplements such as curcumin
  • Some antibiotics such as erythromycin
  • Some antiviral medications such as ritonavir
  • Some antifungal drugs such as ketoconazole and itraconazole
  • Some benzodiazepine sedatives such as oxazepam
  • Some corticosteroids

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