Cialis vs. Sildenafil

See how Cialis and Sildenafil compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Cialis and sildenafil are both PDE5 inhibitors for erectile dysfunction, but Cialis lasts up to 36 hours while sildenafil works for about 4 to 6 hours.

  • Cialis is also FDA-approved for daily use in benign prostatic hyperplasia, while sildenafil is FDA-approved for pulmonary arterial hypertension under the Revatio brand.

  • Both drugs can cause headache, dyspepsia, and nasal congestion, but sildenafil has the longer track record, having been approved in 1998, five years before Cialis.

Cialis vs. Sildenafil Drug Summary

Cialis

Cialis (tadalafil) is a PDE5 inhibitor used to treat erectile dysfunction and benign prostatic hyperplasia (BPH), sometimes both together. It comes as an oral tablet that can be taken daily in a low dose or as needed in a higher dose before sexual activity.

Sildenafil

Sildenafil is a PDE5 inhibitor used to treat erectile dysfunction, taken as an oral tablet only as needed before sexual activity. Under the brand name Revatio, sildenafil is also FDA-approved to treat pulmonary arterial hypertension.

Cialis vs. Sildenafil Side Effects

Cialis

Most common
headache (up to 15%)
dyspepsia (up to 10%)
nasal congestion (up to 4%)
back pain (up to 9%)

Sildenafil

Most common
headache (up to 16%)
dyspepsia (up to 7%)
nasal congestion (up to 4%)
flushing (up to 10%)

Cialis vs. Sildenafil Dosage

Cialis

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 2.5 mg once daily At the start
Maximum dose 20 mg as needed If needed
Dose changes 3 increases As tolerated

Sildenafil

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 25 mg as needed At the start
Maximum dose 100 mg as needed If needed
Dose changes 2 increases As tolerated

Cialis vs. Sildenafil Indications

Cialis

Cialis treats erectile dysfunction and the urinary symptoms of benign prostatic hyperplasia, and it is the only PDE5 inhibitor approved to treat both conditions together with one daily dose. It is sometimes used off-label, under the brand name Adcirca, for pulmonary arterial hypertension.

  • Erectile dysfunction

  • Benign prostatic hyperplasia (BPH) symptoms

  • Combined ED and BPH symptoms

  • Off-label: pulmonary arterial hypertension (as Adcirca)

Sildenafil

Sildenafil treats erectile dysfunction and is FDA-approved under the brand name Revatio for pulmonary arterial hypertension. It is also used off-label for conditions like Raynaud's phenomenon and female sexual arousal disorder.

  • Erectile dysfunction

  • Pulmonary arterial hypertension (as Revatio)

  • Off-label: Raynaud's phenomenon

  • Off-label: female sexual arousal disorder

Cialis vs. Sildenafil Pros and Cons

Cialis

Cialis stands out for its long 36-hour window, which gives more flexibility around timing sexual activity, and for being the only PDE5 inhibitor approved for daily dosing in both ED and BPH. It requires attention to alpha-blocker interactions and, for daily use, consistent adherence.

Pros

  • Lasts up to 36 hours, longer than sildenafil's window

  • Only PDE5 inhibitor with a daily-dose option for ED and BPH together

  • Approved specifically for combined ED and BPH symptoms

  • Less need to plan dosing around a specific moment

Cons

  • Longer half-life means side effects may linger longer if they occur

  • Not recommended with alpha-blockers other than tamsulosin

  • No low-dose 25 mg as-needed option for occasional use

  • Off-label pulmonary hypertension use requires the separate Adcirca brand

Sildenafil

Sildenafil has the longest track record of any PDE5 inhibitor and offers flexible as-needed dosing from 25 mg to 100 mg. It works for a shorter window than Cialis, so timing before sexual activity matters more.

Pros

  • Longest safety track record, approved since 1998

  • Also FDA-approved for pulmonary arterial hypertension (as Revatio)

  • Flexible as-needed dosing from 25 mg to 100 mg

  • No boxed warning on the label

Cons

  • Shorter duration of action requires timing around activity

  • Only available as needed, with no daily-use option

  • Label specifically notes risk of sudden vision or hearing loss

  • Best effect requires dosing about an hour beforehand

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