How Does Tadalafil Work — The PDE5 Mechanism
Tadalafil belongs to the class of phosphodiesterase type 5 (PDE5) inhibitors. The mechanism of action step by step:
- Sexual arousal activates nitric oxide (NO) release in the smooth muscle of the penile corpus cavernosum
- NO activates guanylate cyclase, which produces cGMP (cyclic guanosine monophosphate)
- cGMP relaxes smooth muscle in penile blood vessels — blood flows in, an erection forms
- Without tadalafil: the enzyme PDE5 rapidly breaks down cGMP, ending the erection
- With Cialis Generic: tadalafil inhibits PDE5 → cGMP remains elevated → sustained blood flow → firm erection during sexual activity
Critical: Tadalafil does not produce a spontaneous erection. Sexual arousal is required — without it, the medication has no effect regardless of dose. Tadalafil is not an aphrodisiac and does not affect libido.
Why does tadalafil last 36 hours? Tadalafil's half-life is approximately 17.5 hours — by far the longest of any approved PDE5 inhibitor (sildenafil: 3–5 hours; vardenafil: 4–5 hours). This extended half-life means the medication remains at therapeutic concentration in the blood for up to 36 hours after a single dose, providing a broad window for sexual activity without repeated dosing.
Cialis Generic vs. Viagra Generic vs. Levitra Generic — Full Comparison
| Parameter | Cialis Generic (Tadalafil) | Viagra Generic (Sildenafil) | Levitra Generic (Vardenafil) |
|---|---|---|---|
| Active ingredient | Tadalafil | Sildenafil citrate | Vardenafil |
| Onset of action | 30–60 minutes | 30–60 minutes | 15–30 min (fastest) |
| Duration of effect | Up to 36 hours | 4–6 hours | 4–6 hours |
| Half-life | ~17.5 hours | 3–5 hours | 4–5 hours |
| Daily dosing option | Yes — 2.5mg/5mg | No | No |
| Food effect on absorption | Minimal — take with any meal | High-fat meals delay onset | Moderate food effect |
| Back/muscle pain | Possible (myalgia — unique to tadalafil) | Rare | Rare |
| Visual disturbances | Rare | Occasional (blue tinge — PDE6) | Very rare |
| Approved for BPH | Yes — only PDE5 inhibitor approved for BPH | No | No |
| Best suited for | Spontaneity, frequent activity, daily therapy, BPH | Planned encounters, first-time users, lowest cost | Fastest onset, diabetic men, Viagra intolerance |
36-HOUR WINDOW
Choose Cialis Generic for full-weekend spontaneity — one dose Friday evening covers all of Saturday and Sunday
DAILY THERAPY
Choose Cialis 5mg daily if you are sexually active more than twice a week — constant readiness, no timing required
BPH + ED
Choose Cialis 5mg daily if you have both ED and benign prostatic hyperplasia — one pill treats both conditions simultaneously
FOOD FLEXIBILITY
Choose Cialis Generic if you have unpredictable meal schedules — unlike Viagra, tadalafil works equally well with or without food
Tadalafil's Unique Dual Approval — Erectile Dysfunction and BPH
Tadalafil (Cialis) is the only PDE5 inhibitor approved by Health Canada for both erectile dysfunction and benign prostatic hyperplasia (BPH) — a condition affecting approximately 50% of Canadian men over 50 and over 80% of men over 80. BPH causes lower urinary tract symptoms (LUTS) including urinary urgency, weak stream, incomplete bladder emptying, and nocturia (waking at night to urinate).
How does tadalafil help BPH? The smooth muscle of the prostate, bladder neck, and urethra contains PDE5 — the same enzyme that tadalafil inhibits in penile tissue. By relaxing this smooth muscle, tadalafil reduces urinary outflow obstruction and improves LUTS symptoms. The approved dose for BPH — whether alone or in combination with ED — is 5mg once daily.
For Canadian men diagnosed with both ED and BPH, Cialis 5mg daily is the only medication that treats both conditions with a single daily pill. This combination is particularly relevant because ED and BPH frequently co-occur and share common underlying risk factors including age, cardiovascular disease, diabetes, and metabolic syndrome.
Note: Tadalafil for BPH is distinct from alpha-blockers (tamsulosin, doxazosin) which are also used for BPH. If you already take an alpha-blocker, the combination with tadalafil requires careful medical supervision due to additive blood pressure-lowering effects.
Dosage Guide — On-Demand vs. Daily Tadalafil
| Regimen | Dose | For whom | Key instructions |
|---|---|---|---|
| On-demand — starting dose | 10mg | Most adult men; first-time tadalafil users | Take 30–60 min before activity; max 1 dose per 24h |
| On-demand — maximum dose | 20mg | When 10mg is insufficient | Maximum recommended on-demand dose; do not exceed |
| Daily — standard | 5mg | Frequent sexual activity (>2× per week); BPH; men who prefer no timing | Same time each day; takes 3–5 days to reach steady-state |
| Daily — low starting dose | 2.5mg | Elderly men; renal/hepatic impairment; tolerability concerns | Minimum effective daily dose; can increase to 5mg if needed |
| On-demand — elderly / renal impairment | 5mg | Men 65+; CrCl 31–80 ml/min | Lower starting dose for on-demand use; CrCl <30: avoid tadalafil |
On-demand vs. daily — which is more cost-effective? For men who are sexually active 3+ times per week, daily 5mg tadalafil is typically more economical than repeated 10–20mg on-demand dosing. For men who are active once a week or less, on-demand 10mg or 20mg is more cost-efficient. Your physician can advise based on your pattern of sexual activity.
Food and timing: Unlike sildenafil and vardenafil, tadalafil's absorption is not significantly affected by food — it can be taken with any meal, including high-fat meals. For on-demand dosing, take 30–60 minutes before planned sexual activity. The effect window extends to 36 hours — so a dose taken Friday evening remains active through Saturday afternoon.
Pharmacokinetics of Tadalafil
| Parameter | Value | Clinical significance |
|---|---|---|
| Oral bioavailability | ~80% | High — consistent absorption regardless of food |
| Time to peak (Tmax) | 2 hours (range 30 min–6 hours) | Take 30–60 min before activity for most men |
| Half-life | ~17.5 hours | Longest of any PDE5 inhibitor — enables 36-hour window |
| Protein binding | ~94% | Not dialysable |
| Metabolism | CYP3A4 (liver) | Interactions with CYP3A4 inhibitors/inducers (see below) |
| Elimination | ~61% faecal; ~36% renal (metabolites) | Dose reduction required for severe renal/hepatic impairment |
Cialis Generic vs. Brand Cialis (Eli Lilly) — What Is the Difference?
Both contain identical active ingredient tadalafil at identical dosages. The difference is manufacturer, brand name, and price.
| Parameter | Cialis Brand (Eli Lilly) | Cialis Generic (Tadalafil) |
|---|---|---|
| Active ingredient | Tadalafil | Tadalafil |
| Bioequivalence | Reference product | Proven bioequivalent — legally required |
| Price per 20mg tablet (Canadian pharmacy) | C$25–35 | From C$0.78 (online) |
| Annual cost (on-demand, 2× per week) | C$2,600–3,640 | ~C$80–160 |
Generic manufacturers are legally required by Health Canada to demonstrate bioequivalence — identical tadalafil absorption rate and peak blood concentration. The price difference exists because generic manufacturers do not bear Eli Lilly's original R&D and clinical trial costs. Therapeutic effectiveness is identical.
Side Effects of Cialis Generic (Tadalafil)
Priapism: a painful erection lasting more than 4 hours is a medical emergency. Without immediate treatment it can cause permanent irreversible damage to erectile tissue. Go to the nearest Emergency Room immediately — do not wait.
NAION (Non-Arteritic Anterior Ischaemic Optic Neuropathy): a rare but serious condition — sudden, painless vision loss in one eye — has been reported in a small number of men taking PDE5 inhibitors. It is unclear whether the medication or the underlying cardiovascular risk factors are causative. Men with a history of NAION in one eye should discuss the risks carefully with an ophthalmologist before taking tadalafil.
Contraindications — Who Must Not Take Cialis Generic
- Nitrate medications (nitroglycerin, isosorbide mononitrate, isosorbide dinitrate) — the combination causes severe, potentially fatal blood pressure drop. Absolute contraindication with no exceptions. If you use nitrates for chest pain (angina), tadalafil is contraindicated
- Poppers (amyl nitrite, butyl nitrite) — recreational nitrates; same lethal interaction as prescription nitrates
- Riociguat (Adempas) — a soluble guanylate cyclase stimulator used for pulmonary hypertension; absolute contraindication with all PDE5 inhibitors
- Severe cardiovascular disease or heart attack/stroke within the past 3 months
- Severe hepatic impairment (Child-Pugh C) — tadalafil not studied in this population
- Severe renal impairment (CrCl <30 ml/min) — limited data; avoid or use with extreme caution under medical supervision
- Hereditary degenerative retinal disorders (retinitis pigmentosa) — PDE6 involvement in retinal function
- Uncontrolled low blood pressure (<90/50 mmHg) or uncontrolled high blood pressure (>170/100 mmHg)
- History of priapism or anatomical deformation of the penis (Peyronie's disease) — use only under urologist supervision
- Hypersensitivity to tadalafil or any tablet excipient
Drug Interactions
| Drug / Substance | Interaction | Recommendation |
|---|---|---|
| Nitrates (all forms) | Potentially fatal hypotension | Absolutely contraindicated |
| Alpha-blockers (tamsulosin, doxazosin) | Additive BP lowering — dizziness, fainting | Use with caution; tamsulosin 0.4mg generally tolerated with tadalafil 5mg daily; physician guidance required |
| Strong CYP3A4 inhibitors (ritonavir, ketoconazole, clarithromycin) | Significantly increases tadalafil plasma levels | Ritonavir: max 10mg per 72h. Others: reduce dose; consult physician |
| CYP3A4 inducers (rifampicin, carbamazepine, St. John's Wort) | Reduces tadalafil effectiveness | May require dose adjustment; inform physician |
| Other PDE5 inhibitors (sildenafil, vardenafil) | Additive hypotension | Never combine; minimum 24h gap |
| Antihypertensives (amlodipine, enalapril, metoprolol) | Additive blood pressure reduction — usually mild | Monitor BP; inform prescriber |
| Alcohol | Additive hypotension; impairs erectile response independently | Maximum 2 standard drinks; avoid heavy drinking |
Getting a Tadalafil Prescription in Canada
Tadalafil is a Schedule F prescription medication in Canada — it requires a valid prescription from a licensed Canadian physician. Options for obtaining a prescription:
- Family physician or GP — most straightforward; ED is a recognised medical condition with an established treatment protocol. A physician will also assess cardiovascular health before prescribing
- Urologist — specialist option; particularly relevant if you have concurrent BPH or prostate concerns
- Telehealth — fastest option: Canadian digital health platforms including Maple, Tia Health, Felix Health and Dialogue offer same-day or next-day physician consultations for ED, with electronic prescriptions issued within hours. Felix and Maple are particularly well-known in Canada for ED consultations. Several provincial health plans partially cover telehealth visits
What to tell your doctor: Describe how long ED has been present, your frequency of sexual activity (to determine on-demand vs. daily dosing), any cardiovascular conditions or medications, and whether you take alpha-blockers (important for the tadalafil + alpha-blocker interaction). If you are over 50, mention any urinary symptoms — your physician may assess for BPH and prescribe tadalafil 5mg daily as dual treatment.
Delivery to All Canadian Provinces and Territories
We ship Cialis Generic (Tadalafil) with complete discretion to all provinces and territories across Canada in 4–9 business days. Every order is dispatched in plain, unmarked packaging with no indication of contents on the outside. A tracking number is provided with every order.
Ontario (Toronto, Ottawa, Mississauga, Brampton, Hamilton, London, Windsor) — Quebec (Montreal, Quebec City, Laval, Gatineau, Longueuil) — British Columbia (Vancouver, Surrey, Burnaby, Richmond, Victoria, Kelowna) — Alberta (Calgary, Edmonton, Red Deer, Lethbridge) — Manitoba (Winnipeg, Brandon) — Saskatchewan (Saskatoon, Regina) — Nova Scotia (Halifax, Dartmouth) — New Brunswick (Fredericton, Moncton, Saint John) — Newfoundland and Labrador (St. John's) — Prince Edward Island (Charlottetown) — Northwest Territories, Yukon, Nunavut — and all other cities and communities across Canada.
Frequently Asked Questions — Cialis Generic Canada
Is generic Cialis as effective as brand-name Cialis? Yes — therapeutically identical. Canadian generic drug approval requires bioequivalence: identical tadalafil absorption rate and peak blood concentration to Eli Lilly's Cialis. The only differences are manufacturer, packaging, and price. Eli Lilly's patent has expired and multiple Health Canada-approved generic manufacturers now produce tadalafil.
How long before sex should I take Cialis? For on-demand dosing (10mg or 20mg): take 30–60 minutes before planned sexual activity. The effect window extends up to 36 hours from the time of ingestion — so you have significant flexibility. For daily dosing (5mg): take at the same time each day regardless of sexual plans. After 3–5 days at daily dosing, tadalafil reaches steady-state concentration and no specific pre-sex timing is needed.
Can I take Cialis every day? Yes — 5mg daily is an approved dosing regimen for both ED and BPH. Daily tadalafil maintains a constant therapeutic level in the bloodstream, eliminating the need to time medication around sexual activity. It is particularly suitable for men who are sexually active more than twice a week or who have concurrent BPH.
Why does my back hurt after taking Cialis? Back pain and muscle aches (myalgia) 12–24 hours after taking tadalafil is a well-known side effect specific to tadalafil — not shared by sildenafil or vardenafil. It is caused by tadalafil's inhibition of PDE11A in skeletal muscle tissue. It typically resolves within 48 hours. If the pain is bothersome, try reducing to the 10mg dose, or discuss switching to sildenafil with your physician.
Can I drink alcohol with Cialis? Moderate alcohol consumption (1–2 standard drinks) does not significantly interact with tadalafil for most healthy men. However, larger amounts of alcohol independently impair erectile function and lower blood pressure — increasing the risk of side effects. Avoid heavy drinking on days when you take tadalafil.
Does Cialis help with urinary problems from an enlarged prostate? Yes — tadalafil 5mg daily is the only PDE5 inhibitor approved by Health Canada specifically for BPH. It relaxes smooth muscle in the prostate, bladder neck, and urethra, improving urinary flow and reducing LUTS (lower urinary tract symptoms) including urgency, weak stream, and nocturia. This dual action makes it particularly valuable for the approximately 50% of Canadian men over 50 who have both ED and BPH.
Is Cialis safe for men with high blood pressure? Tadalafil can be used safely in most men with well-controlled hypertension — including those taking antihypertensives. The combination produces an additive mild blood pressure-lowering effect which is usually clinically manageable. However, tadalafil is absolutely contraindicated with nitrates (nitroglycerin, isosorbide), which are sometimes used for hypertension and angina. Always inform your prescribing physician of all medications before starting tadalafil.
Will Cialis work if Viagra didn't? Yes, in many cases. Approximately 50–70% of men who do not respond adequately to sildenafil (Viagra) respond to tadalafil — the two medications have different pharmacokinetic profiles and different durations of action, and individual response to PDE5 inhibitors varies. Tadalafil's 36-hour window also removes timing pressure which can independently improve outcomes.
The information on this page is for educational purposes only and does not constitute medical advice. Tadalafil (Cialis Generic) is a Schedule F prescription medication in Canada. Always consult a licensed Canadian healthcare provider before starting treatment — particularly if you take nitrates, alpha-blockers, antihypertensives, or antiretrovirals. If you experience an erection lasting more than 4 hours, sudden vision or hearing loss, or chest pain during sexual activity, seek emergency medical care immediately — call 911.
