Sexual health
Cialis
tadalafil / pronounced [ta da' la fil]
Long-acting PDE5 inhibitor. 24-36 hour duration. Daily low-dose option for spontaneity.
- Manufacturer
- Eli Lilly
- FDA approved
- 2003
FDA-approved for
- Erectile dysfunction
- Benign prostatic hyperplasia
Why is Cialis prescribed?
Cialis is the brand-name tadalafil, longer-acting than sildenafil. Generic since 2018. Two dosing modes: as-needed (10-20mg) or daily low-dose (2.5-5mg). The daily mode is popular because it allows spontaneous activity without timing pills.
FDA-approved indications:
- Erectile dysfunction
- Benign prostatic hyperplasia
How does Cialis work?
Same mechanism as sildenafil — PDE5 inhibition. Longer half-life (17.5 hours vs 4 hours for sildenafil) means effect lasts longer per dose.
Who qualifies for Cialis?
Adult men with ED. Daily low-dose also FDA-approved for benign prostatic hyperplasia (BPH). Same contraindications as sildenafil (nitrates, alpha-blockers, etc.).
How should Cialis be used?
As-needed: 10-20mg before sexual activity. Daily: 2.5-5mg every day at the same time.
Pharmacokinetic timing: onset 30 min · peak 120 min · duration ~2160 min
What should I do if I forget a dose?
Daily Cialis: if missed, take when remembered if within 12 hours; if longer, skip and resume regular schedule. Do not double up. As-needed Cialis: no missed-dose concept; take 30 minutes before activity, max one dose per 24 hours.
What side effects can Cialis cause?
Back pain, muscle aches (more common than with sildenafil). Headache, flushing, nasal congestion. Same vision/hearing warnings.
What interactions should clinicians watch for?
Same critical contraindication as Viagra: nitrates can cause life-threatening hypotension. Never combine. Caution with alpha-blockers and CYP3A4 inhibitors. Daily low-dose Cialis (2.5-5mg) has the same interaction profile as as-needed dosing — same drugs to avoid, same monitoring.
What special precautions should I follow?
Pregnancy & lactation
Cialis is approved for men only (ED + BPH). Not a relevant pregnancy concern for the typical user.
Alcohol
Tadalafil's long half-life (~17 hours) means alcohol-drug interaction window is longer than with sildenafil. Moderate alcohol (1-2 drinks) is generally compatible. Heavy drinking amplifies dizziness and hypotension risk. The 36-hour window of effect means you may have tadalafil in your system longer than expected — plan alcohol accordingly.
What does Cialis cost?
Generic tadalafil $1-8/tablet. Telehealth $30-100/month depending on dose and as-needed vs daily.
Primary sources
Related clinical resources
What clinicians say
Quotes from published interviews, peer-reviewed commentary, and conference presentations. Each is attributed and linked to the original source.
“Tadalafil was effective and well-tolerated for the treatment of erectile dysfunction. The extended response window after dosing, compared with other PDE5 inhibitors, was associated with patient and partner preference in subsequent comparative studies.”
Source: Journal of Urology — Efficacy and Safety of Tadalafil for the Treatment of Erectile Dysfunction: Results of Integrated Analyses (October 2002 — PMID 12352386)
“The use of Cialis with nitrates is contraindicated. Coadministration of Cialis with nitrates may potentiate the hypotensive effects and cause severe hypotension. Cialis is contraindicated in any patient receiving any form of organic nitrate.”
Source: FDA-approved Cialis (tadalafil) prescribing information — current label (Approved November 2003; current label 2011)