Dr. Ambrish Singal
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PDE5 Inhibitor (Erectile Dysfunction)

Sildenafil

Also known as: Viagra, Manforce, Penegra

Important: This is informational content only. Always consult Dr. Ambrish Singal or your psychiatrist before starting, stopping, or changing any medication.

What is Sildenafil?

Sildenafil is a phosphodiesterase-5 (PDE5) inhibitor used for erectile dysfunction. It enhances the natural erectile response to sexual stimulation and does not cause an erection without stimulation.

How It Works

Inhibits PDE5 enzyme, which normally breaks down cyclic GMP in the corpus cavernosum. By preserving cGMP, sildenafil enhances smooth muscle relaxation and blood flow to the penis during sexual arousal.

Uses

Erectile DysfunctionPulmonary Arterial Hypertension (as Revatio)

How This Drug Starts Working

Works within 30-60 minutes. Lasts 4-6 hours. Must have sexual arousal to work.

Week-by-Week Timeline

1

Dose timing: Take 30-60 minutes before planned sexual activity. On empty stomach: works in 30 minutes. After fatty meal: may take 60-90 minutes.

2

During the window (4-6 hours): Erection possible WITH sexual stimulation. Does NOT cause automatic erection — arousal is required.

3

Repeat use: Many men respond better after 4-6 uses as performance anxiety decreases and they learn how the medication works for them.

4

If first dose doesn't work: Don't give up — try at least 4 times at the correct dose before concluding it's ineffective. Performance anxiety often blocks the response initially.

What Changes First?

The medication works immediately on the vascular mechanism — cGMP is preserved within 30 minutes of taking the pill. However, the PSYCHOLOGICAL benefit (reduced performance anxiety) often takes several successful uses to establish. The physical mechanism + mental relaxation together = reliable erections.

Why Does It Take Time?

The drug itself works quickly (30 min). But if performance anxiety is a factor, the brain needs several SUCCESSFUL experiences to unlearn the fear-failure association. That's why doctors say 'try it at least 4-6 times before judging.'

Complete Dosage Guide

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How to Take

Take ONE tablet 30-60 minutes before sexual activity. Swallow whole with water. On an EMPTY STOMACH for fastest onset (high-fat meals delay absorption by 1 hour and reduce peak effect by 29%).

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Starting Dose

50mg for most men. 25mg if elderly, liver/kidney problems, or taking certain other medications.

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Dose Increases

If 50mg insufficient: increase to 100mg. If 50mg causes too many side effects: try 25mg.

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Maximum Dose

100mg. Do NOT take more than one dose in 24 hours.

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When to Take

Best results: skip heavy meals before, take on empty or light stomach, allow 30-60 minutes before activity. The 'window' lasts about 4-6 hours — you don't need to rush. Works best when relaxed, not anxious.

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If You Miss a Dose

Not applicable — taken as needed, not on a schedule.

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Food & Drink

AVOID high-fat meals before taking (delays and reduces effectiveness). Light snack is fine. Moderate alcohol is okay but excessive alcohol worsens ED. NEVER combine with nitrate medications (nitroglycerin) — fatal blood pressure drop.

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How Long to Take

Used as needed — no maximum treatment duration. Some men transition to daily tadalafil (5mg) for continuous readiness without timing concerns.

Dosage by Age Group

adult

ED: Start 50mg, taken 30-60 minutes before sexual activity. May adjust to 25-100mg. Maximum: 100mg/day. Do not take more than once daily.

child

Not applicable for ED. PAH dosing separate.

elderly

Start 25mg due to increased sensitivity and potential interactions.

Special Populations

Pregnancy

Not applicable (male use). Category B for pulmonary hypertension.

Kidney Conditions

Start 25mg in severe renal impairment.

Liver Conditions

Start 25mg in hepatic impairment. Reduced clearance.

Side Effects

Common

  • Headache
  • Flushing
  • Nasal congestion
  • Dizziness
  • Dyspepsia
  • Visual disturbances (blue-tinted vision)

Serious

  • Priapism (erection >4 hours - medical emergency)
  • Sudden vision loss (NAION)
  • Sudden hearing loss
  • Severe hypotension (with nitrates - CONTRAINDICATED)
  • Cardiac events in at-risk patients

What You Should Know

1.Take 30-60 minutes before sexual activity on an empty stomach for best results
2.This medication REQUIRES sexual arousal to work — it won't cause an automatic erection
3.NEVER take with nitrate heart medications (nitroglycerin, isosorbide) — this is life-threatening
4.Do not take more than once daily
5.Seek emergency care if erection lasts more than 4 hours (priapism)
6.Report any sudden vision or hearing changes immediately
7.A fatty meal before taking it will make it work less quickly
8.Headache and facial flushing are normal and usually decrease with continued use
9.This does not protect against STIs — use appropriate protection

Overdose Risks

May cause severe headache, flushing, dizziness, and priapism. Symptomatic treatment. Avoid with nitrates at all times.

Safe Discontinuation

Can be stopped anytime. No withdrawal effects. Used as needed, not continuously.

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