What Is Cialis (Tadalafil)?
Cialis is a brand-name formulation of tadalafil, a PDE-5 inhibitor. In U.S. prescribing information, tadalafil is indicated for erectile dysfunction, the signs and symptoms of BPH, and ED with BPH.
ED is the inability to get or maintain an erection firm enough for sexual activity. It can have vascular, neurologic, hormonal, medication-related, psychological, or other causes. ED is common, but it is not considered an inevitable or routine part of aging and can sometimes signal an underlying health problem.
BPH, meanwhile, is a noncancerous enlargement of the prostate. As the prostate enlarges, it can affect urine flow and contribute to symptoms such as a weak stream, difficulty starting urination, urinary frequency, urgency, dribbling, and nighttime urination.
Because tadalafil can address both conditions, it may be particularly useful when ED and BPH-related urinary symptoms occur together.
How Does Tadalafil Work?
Tadalafil works by inhibiting the enzyme phosphodiesterase type 5 (PDE-5).
During sexual stimulation, nitric oxide signaling increases cyclic guanosine monophosphate (cGMP) in penile tissue. cGMP promotes smooth-muscle relaxation and increased blood flow into the penis, supporting an erection. PDE-5 normally breaks down cGMP.
By inhibiting PDE-5, tadalafil helps maintain cGMP activity and supports penile blood flow when sexual stimulation is present.
Does Cialis cause an erection automatically?
No.
Tadalafil does not directly create sexual desire and does not normally cause an erection simply because the medication was taken. Sexual stimulation is still required for the erectile response. MedlinePlus also notes that tadalafil does not increase sexual desire or cure the underlying cause of ED.
How may tadalafil help BPH?
The exact mechanisms involved in BPH symptom relief are more complex than its action in ED. PDE-5 inhibition can relax smooth muscle around the prostate, bladder neck, and lower urinary tract, helping reduce some urinary symptoms.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists PDE-5 inhibitors among medications that can help relieve some BPH symptoms.
Cialis Uses: Erectile Dysfunction and BPH
1. Cialis for Erectile Dysfunction
Tadalafil is approved for the treatment of erectile dysfunction.
For ED, tadalafil may be prescribed either:
- As needed before sexual activity, or
- Once daily, allowing sexual activity without timing each dose around intercourse.
The prescribing information specifies different regimens depending on the formulation and clinical situation.
One important characteristic of tadalafil is its relatively long duration of erectile-function benefit. U.S. prescribing information states that as-needed tadalafil can improve erectile function compared with placebo for up to 36 hours after a dose.
This does not mean that an erection lasts for 36 hours. Rather, tadalafil can remain active in the body over that period, making an erectile response possible when sexual stimulation occurs.
2. Cialis for Benign Prostatic Hyperplasia
Tadalafil is also indicated for the signs and symptoms of BPH.
BPH symptoms can include:
- Difficulty starting urination
- Weak or interrupted urine stream
- Dribbling
- Feeling that the bladder has not completely emptied
- Urinary frequency
- Urinary urgency
- Waking during the night to urinate
- Painful urination in some cases
Tadalafil is generally used as a once-daily treatment for BPH. The U.S. prescribing information identifies 5 mg once daily as the standard tadalafil regimen for BPH.
Importantly, BPH symptoms can have causes other than prostate enlargement. Urinary symptoms should therefore be evaluated rather than automatically assumed to be BPH. NIDDK notes that urinary problems can also be associated with conditions such as urinary tract infection, prostatitis, bladder problems, or prostate cancer.
3. Cialis for ED and BPH Together
One of tadalafil’s clinically useful features is that it can address ED and BPH symptoms simultaneously.
The U.S. label specifically includes an indication for ED and the signs and symptoms of BPH. For this combined indication, tadalafil is taken once daily.
This makes tadalafil different from a medication that addresses only erectile function. For someone experiencing both sexual and urinary symptoms, a healthcare professional may consider whether one treatment can appropriately address both problems.
Cialis Dosage and Administration
Tadalafil is available in several tablet strengths, including 2.5 mg, 5 mg, 10 mg, and 20 mg.
For ED, tadalafil may be prescribed as needed or once daily. The current U.S. labeling lists:
- As-needed ED treatment: a typical starting dose of 10 mg, with adjustment based on efficacy and tolerability.
- Once-daily ED treatment: 2.5 mg, which may be increased to 5 mg.
- BPH: 5 mg once daily.
- ED and BPH: 5 mg once daily.
These are label-based dosing frameworks rather than individualized treatment instructions.
Why dose adjustment may matter
Tadalafil exposure can increase when it is taken with certain medicines, including some CYP3A4 inhibitors. Kidney or liver impairment may also affect appropriate dosing. Current U.S. labeling states that severe hepatic impairment is not recommended for tadalafil and that specific renal impairment can require dose modification or make once-daily use inappropriate.
Patients should therefore use the dose prescribed for their specific medical circumstances rather than adjusting the dose themselves.
Common Cialis Side Effects
The most commonly reported adverse reactions with tadalafil include:
- Headache
- Indigestion or dyspepsia
- Back pain
- Muscle aches
- Nasal congestion
- Flushing
- Pain in an extremity
These effects are generally related to tadalafil’s effects on vascular smooth muscle and blood flow.
Back pain and muscle aches
Back pain and myalgia are notable tadalafil adverse effects. They may develop after treatment and generally resolve, but persistent or severe symptoms should be discussed with a healthcare professional.
Serious Cialis Risks and Warning Signs
Although tadalafil is generally well tolerated when appropriately prescribed, some adverse effects require urgent medical attention.
Priapism
Priapism is a prolonged, usually painful erection that does not go away.
An erection lasting more than four hours requires emergency medical treatment because prolonged ischemia can permanently damage erectile tissue.
Tadalafil prescribing information specifically warns patients about priapism.
Sudden Vision Changes
Rare cases of sudden visual loss have been reported with PDE-5 inhibitors.
Sudden loss or significant change in vision after taking tadalafil requires urgent medical evaluation. The relationship between PDE-5 inhibitors and certain rare eye conditions can be complex, so patients should not ignore sudden visual symptoms.
Sudden Hearing Loss
Sudden hearing loss, sometimes accompanied by ringing in the ears or dizziness, has also been reported in association with PDE-5 inhibitors.
Sudden hearing changes warrant prompt medical evaluation.
Cialis and Nitrates: A Critical Drug Interaction
One of the most important tadalafil safety issues involves nitrates.
Tadalafil must not be used with organic nitrates because the combination can produce a dangerous drop in blood pressure. This includes nitrate medications used for certain heart conditions, such as nitroglycerin.
The interaction occurs because both treatments can enhance pathways that promote blood-vessel relaxation.
Why this matters in an emergency
Someone who has taken tadalafil should tell emergency medical personnel before receiving nitrate treatment for chest pain.
Because tadalafil has a relatively long duration of action, the nitrate interaction is particularly important even after the initial dose has been taken.
Cialis and Riociguat
Tadalafil is also contraindicated with guanylate cyclase stimulators, such as riociguat.
Combining these medicines can cause excessive blood-pressure reduction.
Patients taking medications for pulmonary hypertension or other cardiovascular conditions should therefore provide their complete medication list before starting tadalafil.
Cialis With Alpha Blockers and Blood Pressure Medicines
Tadalafil can enhance blood-pressure-lowering effects when combined with certain medications, including:
- Alpha blockers
- Antihypertensive drugs
- Alcohol
The degree of interaction depends on the specific medication and patient’s clinical circumstances.
This is especially relevant for men receiving treatment for BPH, because alpha blockers are also commonly prescribed for urinary symptoms.
A healthcare professional may need to consider timing, dose, blood pressure, and the patient’s overall medication regimen.
Cialis and Alcohol
Large amounts of alcohol combined with tadalafil may increase the risk of low blood pressure, dizziness, headache, or fainting.
The prescribing information specifically warns that tadalafil can potentiate the blood-pressure-lowering effects of alcohol.
That does not mean every person taking tadalafil will experience a problem after drinking alcohol, but heavy alcohol consumption is a meaningful safety consideration.
Who Should Be Careful With Tadalafil?
Before taking Cialis or another tadalafil product, patients should discuss their medical history and medications with a healthcare professional.
Particular attention may be needed in people with:
- Cardiovascular disease
- Low blood pressure
- Uncontrolled high blood pressure
- Significant kidney impairment
- Liver impairment
- Previous serious reactions to tadalafil
- Use of nitrates
- Use of riociguat
- Use of alpha blockers or multiple blood-pressure medicines
- Certain medications that affect CYP3A4 metabolism
The prescribing information recommends specific precautions and dosing considerations for kidney and liver impairment.
Tadalafil and Cardiovascular Health
ED can sometimes be associated with underlying cardiovascular disease, diabetes, obesity, hypertension, or other health conditions. NIDDK notes that cardiovascular and metabolic conditions are among factors associated with ED.
This is one reason ED should not always be treated as an isolated sexual problem.
A healthcare professional may evaluate cardiovascular risk, medications, blood pressure, diabetes status, lifestyle factors, and other possible causes before recommending an ED medication.
When should sexual activity be avoided?
People with significant cardiovascular disease or symptoms that make sexual activity unsafe should receive individualized medical advice before using an ED medication.
Tadalafil should not be viewed as a way to override medical restrictions on sexual activity.
Cialis vs. Other PDE-5 Inhibitors
Tadalafil belongs to the same broad medication class as:
- Sildenafil
- Vardenafil
- Avanafil
These medicines all act through PDE-5 inhibition and can improve erectile function by increasing penile blood flow during sexual stimulation.
However, they differ in pharmacokinetics, duration, dosing schedules, food considerations, adverse-effect profiles, and individual response.
Tadalafil’s relatively long duration is one of its most recognizable characteristics and allows both as-needed and once-daily approaches for ED.
The “best” PDE-5 inhibitor depends on the person’s health, other medications, treatment goals, and response rather than simply which medicine lasts longest.
Cialis for BPH: What It Does and Does Not Do
Tadalafil can improve BPH-related lower urinary tract symptoms, but it does not simply “shrink the prostate.”
BPH is a noncancerous enlargement of prostate tissue. The prostate surrounds part of the urethra, so enlargement can interfere with urine flow.
Treatment options can include:
- Watchful waiting
- Lifestyle changes
- Alpha blockers
- 5-alpha reductase inhibitors
- PDE-5 inhibitors such as tadalafil
- Minimally invasive procedures
- Surgery for selected patients
The appropriate treatment depends on symptom severity, prostate characteristics, complications, other medical conditions, and patient preferences.
Tadalafil With Finasteride for BPH
The U.S. tadalafil label includes information about using tadalafil with finasteride to initiate BPH treatment.
When tadalafil is used with finasteride for this purpose, the labeling recommends the combination for up to 26 weeks, because the incremental benefit of tadalafil decreases over time and the benefit beyond 26 weeks is not established in that indication.
This is a treatment-specific decision that should be made by a healthcare professional.
Cialis in Older Adults
Both ED and BPH become more common with age, making tadalafil particularly relevant in older populations.
However, older adults are also more likely to take multiple medications and have cardiovascular, kidney, or other chronic conditions that can affect treatment choices.
A medication review is therefore important before starting tadalafil, especially when several blood-pressure-lowering medicines or BPH medications are already being used.
When to Seek Emergency Help
Seek urgent medical attention for:
- An erection lasting more than four hours
- Sudden loss of vision
- Sudden hearing loss
- Severe dizziness or fainting
- Symptoms suggesting a serious allergic reaction
- Severe chest pain or other potentially life-threatening cardiovascular symptoms
If chest pain occurs after tadalafil use, tell emergency personnel that tadalafil was taken. Do not self-administer nitrate medication unless a healthcare professional specifically instructs you to do so in the circumstances.
Frequently Asked Questions About Cialis
Is Cialis the same as tadalafil?
Cialis is a brand name for tadalafil. Tadalafil is the active ingredient and belongs to the PDE-5 inhibitor class. Generic tadalafil products are also available in the United States.
How long does Cialis last?
For as-needed ED treatment, tadalafil can improve erectile function compared with placebo for up to 36 hours after a dose. This does not mean a continuous erection; sexual stimulation is still required.
Can Cialis treat both ED and BPH?
Yes. U.S. tadalafil labeling includes treatment of ED and BPH together, using a once-daily regimen.
Does Cialis increase sexual desire?
No. Tadalafil improves the physiological erectile response but does not directly increase sexual desire.
Can Cialis be taken with nitrates?
No. Tadalafil is contraindicated with organic nitrates because the combination can cause a dangerous reduction in blood pressure.
Can tadalafil be used every day?
Yes, tadalafil has FDA-approved once-daily regimens for ED, BPH, and ED with BPH. The appropriate regimen depends on the indication and individual medical circumstances.
Does tadalafil cure BPH?
No. Tadalafil treats the signs and symptoms of BPH; it does not mean the underlying prostate enlargement has been permanently eliminated. BPH can require ongoing monitoring or other treatments.
Is tadalafil safe for everyone?
No medication is appropriate for everyone. Tadalafil has important contraindications and interactions, particularly with nitrates and guanylate cyclase stimulators such as riociguat. Kidney function, liver function, cardiovascular health, and other medications can also affect treatment decisions.
Key Takeaways
Cialis (tadalafil) is a PDE-5 inhibitor used for two important urologic conditions: erectile dysfunction and benign prostatic hyperplasia.
Its major benefits include:
- Improves erectile function when sexual stimulation is present
- Can be used as-needed or once daily for ED
- Has a relatively long duration of erectile-function benefit
- Can improve BPH-related urinary symptoms
- Can treat ED and BPH simultaneously
- Is available in generic tadalafil formulations
Its most important safety considerations include:
- Never combine tadalafil with organic nitrates
- Avoid use with riociguat
- Discuss alpha blockers and blood-pressure medicines with a healthcare professional
- Be cautious with heavy alcohol consumption
- Seek emergency care for an erection lasting more than four hours
- Seek prompt evaluation for sudden vision or hearing changes
- Kidney and liver impairment may require treatment modification
Medical Disclaimer
This article is intended for educational and informational purposes only and does not replace medical advice, diagnosis, or treatment from a qualified healthcare professional. Cialis and tadalafil are prescription medicines, and treatment decisions should be based on an individual’s medical history, current medications, kidney and liver function, cardiovascular status, and other clinical factors. Do not start, stop, increase, or decrease tadalafil without professional guidance.
