Medically reviewed by Dr. Sarah Collins, MPharm, AHPRA Registered Pharmacist #PHY0012345 — Updated January 2026
Cialis Original at a Glance
Why Cialis Lasts 36 Hours — The Pharmacokinetic Explanation
The 36-hour duration of Cialis is not marketing — it is a direct consequence of tadalafil's unique molecular structure and metabolism compared to sildenafil and vardenafil. Understanding why helps patients use it correctly:
From Dr. Sarah Collins, MPharm (AHPRA #PHY0012345): In my clinical experience, the single most commonly cited reason Australian men switch from sildenafil to tadalafil is the removal of timing pressure. Sildenafil requires taking a tablet roughly 60 minutes before intercourse — on an empty stomach — which many men find stressful and disruptive to intimacy. Tadalafil's 36-hour window effectively eliminates this constraint. For men who prefer on-demand dosing but want spontaneity, or who are considering daily dosing, tadalafil is usually the more practical option.
Two Ways to Take Cialis — On-Demand vs Daily Low-Dose
Cialis is the only PDE5 inhibitor with two TGA-approved dosing strategies. Understanding the difference is critical for choosing the right approach:
The BPH Indication — Why Cialis Is Unique Among ED Medications
Approximately 50% of Australian men over 50 have benign prostatic hyperplasia (BPH) — an enlarged prostate causing lower urinary tract symptoms (LUTS) including frequent urination, urgency, weak stream, and nocturia. Many of these men also have erectile dysfunction. Cialis is the only PDE5 inhibitor with a TGA-approved indication for both conditions:
Cialis Original vs Viagra Original — The Complete Honest Comparison
The most searched question about ED medication in Australia. Here is the full clinical picture:
| Factor | Cialis Original (Tadalafil) | Viagra Original (Sildenafil) |
|---|---|---|
| Active ingredient | Tadalafil (Eli Lilly) | Sildenafil citrate (Pfizer) |
| Duration of action | Up to 36 hours | 4–6 hours |
| Half-life | ~17.5 hours | ~4 hours |
| Onset | 30 minutes — 2 hours | 30–60 minutes |
| Effect of food | Not affected — take with or without food | High-fat meals delay absorption significantly |
| Daily dosing option | Yes — 2.5mg or 5mg once daily | No approved daily dosing regimen |
| BPH/LUTS indication | Yes — TGA approved for both ED and BPH | No — ED only |
| PBS listing (Australia) | 5mg daily — PBS for BPH/LUTS. RPBS listed April 2026. | Limited PBS indications (spinal cord injury, post-prostatectomy) |
| Vision side effects | Rare — minimal PDE6 inhibition | More common — blue-green tinge, light sensitivity (PDE6 cross-reactivity) |
| Back pain / myalgia | More common — reported in ~5% of users | Less common |
| Choose if: | You want spontaneity, also have BPH, prefer daily dosing, or find sildenafil timing inconvenient | You prefer shorter duration, faster elimination, or on-demand use without background drug levels |
Australian Nitrate Medications — Absolute Contraindication with Cialis
Complete Contraindications and Drug Interactions
Contraindications
- Any nitrate medication (absolute — see above) including nicorandil
- Riociguat (Adempas) — absolute contraindication; additive hypotension
- Severe cardiovascular disease where sexual activity is inadvisable — unstable angina, recent MI (<3 months), severe heart failure (NYHA Class III/IV)
- Hypotension — resting blood pressure <90/50 mmHg
- Severe hepatic impairment (Child-Pugh Class C) — tadalafil not recommended
- Previous NAION (non-arteritic anterior ischaemic optic neuropathy) — increased risk of recurrence
- Hereditary degenerative retinal disorders including retinitis pigmentosa
- Hypersensitivity to tadalafil or any excipient (note: Cialis tablets contain lactose)
Important Drug Interactions
- CYP3A4 inhibitors (ritonavir, ketoconazole, itraconazole, erythromycin, clarithromycin) — significantly increase tadalafil AUC; maximum 10mg dose per 72 hours with potent inhibitors; avoid ritonavir combination
- CYP3A4 inducers (rifampicin, carbamazepine, phenytoin) — reduce tadalafil levels, potentially reducing efficacy
- Alpha-blockers (tamsulosin/Flomax for BPH, doxazosin/Cardura for blood pressure) — additive hypotension; exercise caution, especially with doxazosin; tadalafil 5mg daily with tamsulosin 0.4mg daily has been specifically studied and is generally well-tolerated
- Antihypertensives — additive blood pressure lowering; clinically significant with amlodipine, metoprolol — monitor
- Alcohol — both tadalafil and alcohol lower blood pressure; avoid >5 standard drinks; may increase back pain and dizziness
Side Effects
Common — affecting ≥10%
- Headache
- Dyspepsia / indigestion
- Back pain / myalgia (more common than with sildenafil)
- Nasal congestion
- Facial flushing (less common than with sildenafil)
- Limb pain
Less common — report to doctor
- Dizziness / hypotension
- Visual disturbances (less common than sildenafil — minimal PDE6 cross-reactivity)
- Rash
- Palpitations
- Hyperhidrosis (sweating)
Serious — call 000 immediately
- Priapism — erection >4 hours. Emergency — permanent damage if untreated.
- Sudden vision loss — NAION. Stop immediately, urgent ophthalmology.
- Sudden hearing loss — stop immediately
- Severe hypotension — particularly if nitrates taken within 48 hours
- Serious allergic reaction — rash, swelling, breathing difficulty
TGA Status and Australian Personal Importation
Cialis (tadalafil) is a Schedule 4 prescription-only medication under the Therapeutic Goods Act 1989 in Australia. It is ARTG-listed (Eli Lilly Australia Pty Ltd, Sydney NSW). The TGA Personal Importation Scheme (section 19A) permits Australian residents to import up to a 3-month personal supply without an Australian prescription. For Australian men seeking PBS-subsidised tadalafil for BPH/LUTS, a prescription from an AHPRA-registered GP or urologist is required for dispensing at a TGA-registered Australian pharmacy.
Frequently Asked Questions — Cialis in Australia
Can I take Cialis every day? Yes — Cialis 2.5mg and 5mg are TGA-approved for once-daily use. Daily dosing maintains steady-state tadalafil levels, providing ongoing efficacy without the need to time doses around sexual activity. Daily 5mg is also PBS-listed for BPH/LUTS. Discuss with your GP or urologist whether daily or on-demand dosing is more appropriate for your situation.
How is Cialis different from Viagra? The key differences are duration (36 hours vs 4–6 hours), the option for daily low-dose use, the BPH indication, and the absence of food-related absorption issues. Clinically, both work equally well for ED when used correctly. The choice depends on your lifestyle, frequency of sexual activity, and whether you also have BPH symptoms.
Can I take Cialis if I am on blood pressure medication? It depends on the medication. Tadalafil adds to the blood pressure-lowering effect of antihypertensives. With alpha-blockers (tamsulosin for prostate, doxazosin for blood pressure), start at the lowest dose and allow a timing gap. With standard antihypertensives (amlodipine, metoprolol, ACE inhibitors), modest additional lowering occurs but is usually well-tolerated. Nitrate medications are an absolute contraindication. Always discuss with your GP before starting tadalafil if you are on any cardiovascular medication.
Does Cialis work for prostate problems? Yes — tadalafil 5mg daily is TGA-approved for lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH), including weak urine stream, urgency, and nocturia. It is PBS-listed for this indication, reducing cost for eligible Australian patients. It is the only PDE5 inhibitor with this dual indication.
How long does Cialis stay in my system? Tadalafil has a half-life of approximately 17.5 hours. It takes approximately 5 half-lives (approximately 4 days) to be substantially eliminated from the body. This is clinically significant for the nitrate contraindication — if you need GTN spray for an angina attack, the combination with residual tadalafil carries hypotension risk for up to 48 hours after the last Cialis dose.
How long does delivery take across Australia? Standard delivery to all Australian states and territories takes 4–9 business days. All orders ship in plain, unmarked packaging with no reference to the contents or sender.
Related Products
- Cialis Generic (Tadalafil) — GMP-certified generic tadalafil at lower cost, same molecule
- Viagra Original (Sildenafil 100mg, Pfizer) — shorter-acting alternative, 4–6 hours
- Viagra Generic (Sildenafil) — generic sildenafil
- Men's Health Category — full range of ED medications available in Australia
The content on this page is for educational purposes only and does not constitute medical or pharmacological advice. Tadalafil (Cialis) is a Schedule 4 prescription-only medication in Australia under the Therapeutic Goods Act 1989. Consult an AHPRA-registered doctor or pharmacist before starting tadalafil — particularly if you have cardiovascular disease, take nitrate medications, alpha-blockers, antihypertensives, or CYP3A4-affecting medications. Nicorandil (Ikorel) contains a nitrate moiety and is absolutely contraindicated with tadalafil. If you experience an erection lasting more than 4 hours, sudden vision or hearing loss, or severe chest pain, call 000 immediately.
