Cialis

What is Cialis (tadalafil)?

Cialis is the brand name for tadalafil, a prescription PDE5 inhibitor used to treat erectile dysfunction and benign prostatic hyperplasia (BPH). Many men prefer tadalafil because it offers more flexibility and less timing pressure than shorter-acting ED medications. It may remain effective for up to 36 hours, which is why it is often discussed as the “weekend pill.”

The medicine requires sexual stimulation to produce an erection — it is not an aphrodisiac. Cialis is FDA-approved for erectile dysfunction and for the treatment of BPH symptoms, and tadalafil is also used in other clinical settings under different product labeling.

This information is educational only and does not replace professional medical advice, diagnosis, or treatment.

Medically accurate dosing (approved ranges)

Only the following tadalafil dosages are supported by regulatory guidance and standard clinical practice for ED and BPH: 2.5 mg, 5 mg, 10 mg, and 20 mg. Higher doses (e.g., 50 mg+) are not supported by FDA/Health Canada recommendations for tadalafil and are not included here.

Dosage table

How Cialis works

Tadalafil inhibits the PDE5 enzyme, enhancing cGMP signaling and promoting smooth muscle relaxation in the corpus cavernosum. The medicine requires sexual stimulation to produce an erection — it is not an aphrodisiac and will not cause spontaneous erections without stimulation.

• Onset: Many men experience an onset within 30–60 minutes for on‑demand dosing; onset may be slower in some individuals or if taken with a high‑fat meal.
• Duration: Tadalafil’s duration can extend up to 36 hours for some patients, which is longer than most other PDE5 inhibitors.
• Daily vs on‑demand: Daily dosing (2.5–5 mg) provides continuous PDE5 inhibition for men who prefer not to plan dosing around sexual activity. On‑demand dosing (10–20 mg) is taken prior to sexual activity.

Cialis vs Viagra

Brand Cialis vs Generic tadalafil

Safety and precautions

This section highlights clinically important safety information. It is not a substitute for personalized medical advice from a prescriber or pharmacist.

Contraindications

• Concurrent use of nitrates (e.g., nitroglycerin, isosorbide mononitrate) — combination can cause profound, potentially life‑threatening hypotension.
• Known hypersensitivity to tadalafil or any excipients in the formulation.
• Patients for whom sexual activity is inadvisable because of cardiovascular status.

Nitrates and interacting medications

Do not take tadalafil with nitrates or nitric oxide donors. Inform your prescriber about all prescription, over‑the‑counter, and herbal medications — particularly alpha‑blockers, some antihypertensives, protease inhibitors, and certain antifungals and macrolide antibiotics which can alter tadalafil levels.

Alcohol and recreational substances

Moderate alcohol use may be tolerated, but excessive alcohol increases risks of dizziness and blood‑pressure effects and may impair performance. Do not combine tadalafil with recreational inhaled nitrite products (“poppers”).

Priapism and vision/hearing changes

Seek immediate medical attention for erections lasting more than 4 hours (priapism) or sudden vision or hearing loss. These are rare but serious events associated with PDE5 inhibitors.

Cardiovascular precautions

Assess cardiovascular status before initiating therapy in men with known cardiac disease. Tadalafil can cause symptomatic hypotension in susceptible individuals. Adjust dosages in significant renal or hepatic impairment per product labeling and clinical judgment.

Who should not take Cialis

• Anyone taking nitrates for chest pain or who recently used recreational nitrates.
• Men with a known allergy to tadalafil or formulation excipients.
• Patients advised against sexual activity by a healthcare professional due to cardiovascular risk.
• Those with severe hepatic impairment or end‑stage renal disease without specialist guidance (dose adjustments may be required).

Possible side effects

Common (usually mild and transient)

• Headache
• Flushing
• Indigestion (dyspepsia)
• Back pain and muscle aches (may occur 12–24 hours after dosing and usually resolve within 48 hours)
• Nasal congestion or runny nose

Serious (seek medical attention)

• Erection lasting more than 4 hours (priapism) — urgent treatment needed to avoid permanent damage.
• Sudden decrease or loss of vision in one or both eyes.
• Sudden hearing decrease or ringing in the ears, sometimes with dizziness.
• Severe hypotension, fainting, or chest pain.

Missed dose and overdose

If using daily dosing and you miss a dose, take it as soon as you remember unless the next scheduled dose is near; do not double doses. For on‑demand dosing, do not take more than one tadalafil dose within 24 hours. In case of suspected overdose, seek emergency medical care. Do not use unapproved high doses or recreationally marketed tadalafil products. If a dose is not part of standard prescribing guidance, it should not be treated as a routine option.

Storage

Store at room temperature in the original package, protected from moisture and heat. Keep out of reach of children. Do not use expired medication.

Frequently asked questions (FAQ)

Medical references

Key sources used to prepare this content:

Related internal links

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