Viagra (Sildenafil Citrate)
Also sold as: Viagra, Penegra, Manforce, Suhagra, Caverta, Revatio (pulmonary HTN)
Pregnancy
Cat N/A
Lactation
Caution
Schedule
H
Forms
Tablet 25mg, 50mg, 100mg (ED) +2
Indications
- Erectile dysfunction (ED)
- Pulmonary arterial hypertension (PAH) — Revatio
Adult Dosing
Erectile dysfunction
50 mg PO approximately 1 hour before sexual activity (range 25-100 mg)
Take on empty stomach (food delays onset). Effect lasts 4-6 hours. Max once daily.
PAH (Revatio)
20 mg PO TDS
Ongoing
Pediatric Dosing
Not for paediatric ED. PAH: specialist use only with careful risk-benefit assessment.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| CrCl < 30 mL/min | Start 25 mg (ED) — clearance reduced. PAH: no specific adjustment but monitor. |
Hepatic Adjustment
Start 25 mg (ED) in hepatic impairment — Child-Pugh A/B. Avoid Child-Pugh C.
Pregnancy & Lactation
Pregnancy: Category N/A
Not indicated in men. PAH in women: Category B (used in pregnancy for PAH — maternal risk of PAH > fetal drug risk).
Lactation: Caution
Sildenafil is used in PAH in breastfeeding women — limited data; monitor infant.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Nitrates (isosorbide mononitrate, GTN, amyl nitrite) | ABSOLUTE CONTRAINDICATION — fatal hypotension. No time interval is safe. | Major |
| Riociguat | ABSOLUTE CONTRAINDICATION — severe hypotension | Major |
| Alpha-blockers (tamsulosin, doxazosin) | Significant hypotension — use lowest doses of both; start alpha-blocker first and establish stable dose before adding sildenafil | Major |
| CYP3A4 inhibitors (ritonavir, ketoconazole, itraconazole, clarithromycin) | Dramatically increase sildenafil levels — reduce to 25 mg (ED); 20 mg max TDS (PAH) | Major |
| CYP3A4 inducers (rifampicin, carbamazepine) | Reduce sildenafil levels — may need dose increase | Moderate |
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Side Effects
Common
- Headache (most common — vasodilation)
- Flushing
- Dyspepsia
- Nasal congestion
- Visual disturbances (blue tinge, blurred)
- Dizziness
Serious / Discontinue If
- Severe hypotension (with nitrates — fatal)
- Non-arteritic anterior ischaemic optic neuropathy (NAION — sudden vision loss; risk factors: diabetes, hypertension, vascular disease)
- Sudden hearing loss
- Priapism (> 4 hours — urological emergency)
- MI or arrhythmia (in high cardiac risk patients)
- Melanoma risk (theoretical — ongoing study)
Contraindications
- Any nitrate use (short or long-acting)
- Riociguat
- Severe hypotension (< 90/50 mmHg)
- Recent stroke or MI (< 6 months)
- Severe hepatic impairment
- Known hereditary degenerative retinal disorders
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Manforce 50mg | Mankind | 4 tab ₹285 |
| Penegra 50mg | Zydus | 4 tab ₹265 |
| Suhagra 50mg | Cipla | 4 tab ₹245 |
| Caverta 50mg | Sun Pharma | 4 tab ₹285 |
| Viagra 50mg | Pfizer | 4 tab ₹985 |
Monitoring Required
- Blood pressure (pre-treatment cardiovascular risk assessment)
- Visual function (NAION risk)
- Erectile function response (patient-reported)
Patient Counseling Points
- ⚠️ NEVER take with nitrate tablets or sprays (including GTN spray) — can cause fatal blood pressure drop
- Take 30-60 minutes before activity, on an empty stomach for fastest onset
- Sexual stimulation still required — not an automatic erection
- Erection lasting > 4 hours: go to emergency immediately (priapism — permanent damage if untreated)
- Report any sudden vision or hearing loss immediately
- Avoid excessive alcohol — worsens hypotension and reduces efficacy
- Effect lasts ~4-6 hours; maximum one tablet per day
Stop Googling drug references mid-consultation
EasyClinic auto-flags Viagra interactions, renal cutoffs, and pregnancy warnings the moment you write the prescription. Built-in safety net for every Indian doctor.
Clinically reviewed by: Dr. Rajiv Nair, MCh (Urology), Consultant Urologist
Last reviewed: 2026-04-01
References
- BNF — Sildenafil
- EAU Erectile Dysfunction Guidelines 2023
- ESC PAH Guidelines 2022
- FDA Sildenafil Prescribing Information