Most men choose between Sildenafil and Tadalafil without knowing what matters: the bloodwork that reveals whether you actually need medication, and whether it will work. These two medications are the most prescribed ED treatments globally, available in India as generics for as little as 50 INR per dose. But choosing between them means understanding not just how they work, but which fits your lifestyle, your medical history, and your goal. One isn't universally "better" — it depends on you.
To understand Sildenafil and Tadalafil, you need to know what happens during erectile dysfunction.
In a healthy erection, sexual stimulation triggers the release of nitric oxide in penile tissue. Nitric oxide activates an enzyme called guanylate cyclase, which increases levels of a messenger molecule called cGMP. Elevated cGMP relaxes smooth muscle in penile arteries, blood flow increases, and an erection happens.
The problem: an enzyme called phosphodiesterase-5 (PDE5) breaks down cGMP. When PDE5 is overactive or when cardiovascular disease or hormonal dysfunction limits nitric oxide production, cGMP drops — and the erection fails.
PDE5 inhibitors (Sildenafil and Tadalafil) block this enzyme. They allow cGMP to accumulate, keeping smooth muscle relaxed and blood flow sustained. But — and this is critical — they only work if there's sexual stimulation and if your vascular system and hormones are intact. If your testosterone is low, your arteries are damaged, or your glucose is uncontrolled, the medication has a harder time working. This is why bloodwork is non-negotiable.
Both Sildenafil and Tadalafil work the same way. The differences are in pharmacokinetics — how fast they work, how long they last, and how your body metabolizes them.
Sildenafil is a short-acting PDE5 inhibitor. Take it 30-60 minutes before sex, and it peaks in your blood within 1-2 hours.
Onset: 30-60 minutes (faster on an empty stomach, slower after a heavy meal)
Duration: 4-6 hours (it leaves your body relatively quickly)
Dosing: 50mg or 100mg, taken as-needed before sexual activity
Food interaction: Sildenafil is significantly affected by food. A high-fat meal delays onset by 30-40 minutes and reduces peak concentration. Take it on an empty stomach or after a light meal for best results. This is the major disadvantage compared to Tadalafil.
Predictable window: If you take Sildenafil at 9 PM, it will be gone by 3 AM. This is an advantage if you want a defined window and prefer the drug to wear off completely.
Repeated dosing: You can take it multiple times daily if needed, though most men take it once per occasion. Each dose is independent.
Most side effects are mild and decrease with repeated use as your body tolerates the medication.
Brand (Viagra): 500-800 INR per 100mg tablet
Generics (Vigore, Manforce, Kamagra): 50-150 INR per 50-100mg tablet
Generic Sildenafil is bioequivalent to brand Viagra — same active drug, different manufacturer. Always verify your pharmacy dispenses licensed generics from DCGI-approved manufacturers.
Tadalafil is a long-acting PDE5 inhibitor with a half-life of 17.5 hours. This means half of each dose is still in your system at 17.5 hours, and traces persist for 36+ hours.
Onset: 30 minutes (same as Sildenafil, but faster and more reliable)
Duration: Up to 36 hours (hence the name "the weekend pill")
Dosing options: Two strategies —
Food-independent: Tadalafil works equally well after food or on an empty stomach. This is a major advantage — you don't have to plan around meals. Have dinner, take the medication, and expect it to work as expected.
Extended window: The 36-hour duration means one dose covers you for an entire weekend. Take it Friday evening, and you're covered through Sunday. This appeals to men who like spontaneity and unpredictability.
Daily dosing option: Low-dose Tadalafil (5mg daily) keeps you in a constant state of PDE5 suppression. This option is ideal for men with frequent sexual activity (2+ times per week) or men who want to "set it and forget it" without timing considerations.
The back pain is unique and noteworthy. It's more common at higher doses and typically mild, but some men find it intolerable. If you experience back pain on as-needed 20mg, switching to daily 5mg often reduces or eliminates it.
Brand (Cialis): 600-1000 INR per 20mg tablet or 400-700 INR per 5mg tablet
Generics (Tadacip, Tadalis, Tadalista): 80-200 INR per 20mg, 60-120 INR per 5mg
Generic Tadalafil is bioequivalent — same drug, lower cost. Daily 5mg is often cheaper per month than as-needed 20mg if you use it frequently.
| Factor | Sildenafil (Viagra) | Tadalafil (Cialis) |
|---|---|---|
| Onset | 30-60 min | 30 min (faster, more reliable) |
| Duration | 4-6 hours | 36 hours |
| Food effect | Significant (delays onset) | None |
| Dosing flexibility | As-needed only | As-needed 20mg OR daily 5mg |
| Best for spontaneity | No (requires 1-hour planning) | Yes (especially daily 5mg) |
| Headache risk | 20-30% (most common side effect) | 13-15% (less common) |
| Back pain | Rare | 10-15% (unique to Tadalafil) |
| Cost per dose (India) | 50-150 INR (generic) | 80-200 INR (generic as-needed) |
| Cost per month (frequent use) | 1500-4500 INR (3x/week) | 400-800 INR (daily 5mg) |
| Interactions with alcohol | Enhanced blood pressure drop | Enhanced blood pressure drop (longer exposure) |
| Contraindication: nitrates | Absolute — life-threatening | Absolute — life-threatening |
Here's what most men don't know: 40% of men under 40 with erectile dysfunction have low testosterone or undiagnosed diabetes. The PDE5 inhibitor alone won't fix that — it treats the symptom (penile hemodynamics), not the cause (hormonal dysfunction or metabolic disease).
Taking Sildenafil or Tadalafil without knowing what's driving your ED is like taking a headache pill for a brain tumor. The medication might work for the immediate problem, but you're ignoring the underlying issue.
1. Testosterone (Total and Free)
Low testosterone causes ED. If your testosterone is below 300 ng/dL, a PDE5 inhibitor alone will have limited efficacy. You need testosterone replacement (TRT) or clomiphene to restore hormone levels. Many men see their ED resolve once testosterone is optimized.
2. Prolactin
Elevated prolactin inhibits erectile function and libido. High prolactin can be from a pituitary tumor, dopamine antagonists (antipsychotics), or unknown causes. If it's high, treating the cause (medication adjustment, pituitary imaging) is essential before PDE5 inhibitors.
3. Fasting Glucose and HbA1c
Diabetes damages blood vessels and nerves controlling erections. Uncontrolled glucose (HbA1c >7%) makes ED medication less effective. Optimal glucose control is required for good outcomes.
4. Lipid Panel (Cholesterol, LDL, HDL, Triglycerides)
High cholesterol and elevated triglycerides indicate endothelial dysfunction — the very mechanism driving ED. Statin therapy improves ED outcomes alongside PDE5 inhibitors.
5. Thyroid Function (TSH, Free T4)
Hypothyroidism causes ED. Thyroid replacement improves erectile function and should be initiated before PDE5 inhibitors if present.
6. Renal Function (Creatinine, eGFR)
Both Sildenafil and Tadalafil are metabolized by the kidneys. If your kidneys are compromised, medication clearance is delayed — dosing needs adjustment.
arq.'s approach: We test all of these before prescribing. If testosterone is low, we add TRT. If glucose is high, we prescribe a diabetes management protocol. If prolactin is elevated, we investigate. Your ED medication is one piece of a comprehensive protocol addressing the underlying causes.
In clinical trials, both medications have similar efficacy: approximately 70-80% of men report improved erections. However, individual response varies significantly.
Factors affecting efficacy:
Many men who think they're "non-responders" to PDE5 inhibitors actually have underlying metabolic or hormonal dysfunction. Once these are treated, medication efficacy improves dramatically.
India's pharmaceutical manufacturing is among the world's best. Generic Sildenafil and Tadalafil are widely available, DCGI-approved, and bioequivalent to brand versions at a fraction of the cost.
To verify you're getting licensed generics:
Concurrent nitrate use (CRITICAL): Nitroglycerin, isosorbide dinitrate, and other nitrates are used for angina. Combining them with Sildenafil or Tadalafil causes catastrophic blood pressure drop and can be fatal. This is non-negotiable — if you're on nitrates, you cannot use PDE5 inhibitors.
Alpha-blockers (Tamsulosin, Doxazosin): Used for benign prostate hyperplasia or high blood pressure. Combined with PDE5 inhibitors, they cause significant blood pressure drop. If you're on an alpha-blocker, your physician must adjust your protocol carefully — sometimes switching medications or spacing doses.
Antifungals (Ketoconazole, Itraconazole): These inhibit the enzyme (CYP3A4) that metabolizes both Sildenafil and Tadalafil. Combining them can dangerously increase drug concentration. Dose adjustment is required.
Protease inhibitors (for HIV): Similar enzyme inhibition — careful dosing required.
Riociguat: A pulmonary hypertension drug. Absolute contraindication with both PDE5 inhibitors.
Blood pressure medications (ACE inhibitors, beta-blockers, calcium channel blockers): Additive blood pressure-lowering effect. Not a contraindication, but your blood pressure should be monitored. If you're on multiple antihypertensives, physician oversight is important.
Alcohol: Enhances blood pressure drop, increases dizziness, headache, and flushing risk. Light alcohol (1-2 units) with Sildenafil is generally tolerable; with Tadalafil's extended duration, even light drinking increases side effects. Moderation is advised.
Do you prefer spontaneity without planning?
→ Tadalafil daily 5mg or as-needed 20mg (lasts 36 hours)
Do you have planned, predictable sexual encounters?
→ Sildenafil (as-needed, short-acting, clear window)
Do you eat heavily before sex or can't control meal timing?
→ Tadalafil (food-independent)
Does headache bother you significantly?
→ Tadalafil (13-15% incidence vs 20-30% for Sildenafil)
Are you concerned about side effects lingering?
→ Sildenafil (clears in 6 hours vs 36 hours for Tadalafil)
Do you have frequent sexual activity (3+ times/week)?
→ Tadalafil daily 5mg is more economical and convenient
Do you experience back pain easily?
→ Sildenafil (back pain is unique to Tadalafil)
Which medication is right for you? It depends on bloodwork you probably haven't done yet. Talk to an arq. physician who will test first, then prescribe →
Standard ED clinics ask a few questions, sell Sildenafil or Tadalafil, and you're done. arq. doesn't work that way.
arq.'s difference:
The core message: ED medication works best when it addresses the root cause, not just the symptom.
Sildenafil (Viagra) works 4-6 hours, best for planned encounters. Tadalafil (Cialis) lasts 36 hours, ideal for spontaneity. Tadalafil 5mg daily is emerging as a cardiovascular and metabolic health intervention beyond ED. Both require cardiac screening first.
| Parameter | Sildenafil (Viagra) | Tadalafil (Cialis) |
|---|---|---|
| Onset | 30–60 min | 30–60 min (less food effect) |
| Duration | 4–6 hours | 36 hours |
| Food Interaction | High-fat meal delays effect | Minimal impact |
| Standard Dose | 50–100 mg | 10–20 mg on-demand |
| Daily Dose | Not recommended daily | 5 mg daily available |
| Cost/Pill (India) | ₹50–120 (generic) | ₹30–80 (generic) |
| Side Effects | Headache, flushing, indigestion | Back pain, myalgia, headache |
| Best For | Planned, occasional use | Spontaneity, frequent activity |
| Cardiovascular Benefit | Minimal beyond ED treatment | Daily 5mg improves endothelial function, BPH |
No AI chat. No templates. A specialist reads your panel against South Asian-calibrated ranges and writes the protocol on a 15–20 minute video consult — inside 7 days of your home draw.