Can I get it?
Yes, if a doctor decides it is right for you. Sildenafil is authorised in the EU and can be prescribed after a medical review.
SildenafilPrescription only
Online medical consultation for Sildenafil.
An EU-licensed doctor reviews your case and, if eligible, issues an electronic prescription valid at any EU pharmacy under Directive 2011/24/EU.
- Onset in 30–60 minutes
- Effect window of ~4–6 hours
- The best-known, most-studied PDE5
Start consultationStart consultation · €35
Full refund if a review is not approved · Medication, if prescribed, is dispensed and paid for separately at a pharmacy.
IN PLAIN TERMS
What Sildenafil is, and how to get treatment
Sildenafil is a prescription tablet for erectile dysfunction, first authorised across the EU in 1998. It relaxes the blood vessels in the penis so that more blood can flow in when you are sexually aroused. It does not create arousal on its own — sexual stimulation is still needed for it to work. It is usually taken about an hour before sex, and it cannot be used together with nitrate heart medicines.
Sildenafil has been authorised for use in the EU since 13 September 1998, so a licensed doctor can prescribe it when it is clinically appropriate for you.
What can I take instead?
Our doctors review every Sexual health option and recommend what fits your history and goals.
See all Sexual health optionsWhat do the studies show?
Every trial behind Sildenafil is listed below with how many people took part and whether the results are peer-reviewed or a company announcement.
Jump to the studiesVERIFIED EVIDENCE
Sildenafil: evidence and regulatory guide.
WHAT IT IS
How it works
Sildenafil blocks an enzyme called PDE5 that normally ends an erection, so when a man is sexually aroused the blood vessels in the penis stay relaxed and more blood can flow in.
- PDE5
DEVELOPMENT STAGE
EU-authorised medicine
Trial register3 registered trials
Every NCT identifier links to its ClinicalTrials.gov record. A readout is not the same as peer-reviewed publication.
| TRIAL / NCT | POPULATION | PARTICIPANTS | STATUS | READOUT / COMPLETION |
|---|---|---|---|---|
| Sildenafil Study Group — 24-week dose-response study | Men with erectile dysfunction of organic, psychogenic and mixed causes | 532 | Read out | 1998-05-14 |
| Sildenafil Study Group — 12-week flexible dose-escalation study | Men with erectile dysfunction of organic, psychogenic and mixed causes | 329 | Read out | 1998-05-14 |
| Sildenafil Study Group — 32-week open-label extension | Men continuing from the dose-escalation study | 225 | Read out | 1998-05-14 |
What the studies reported
Results are grouped by source and evidence grade so journal data and manufacturer announcements cannot be confused.
Peer-reviewed
Sildenafil Study Group (Goldstein I, Lue TF, Padma-Nathan H, Rosen RC, Steers WD, Wicker PA). Oral sildenafil in the treatment of erectile dysfunction. N Engl J Med 1998;338(20):1397-1404. doi:10.1056/NEJM199805143382001 (PMID 9580646)| DOSE OR GROUP | MEAN WEIGHT CHANGE | WEEKS |
|---|---|---|
| 100 mg | Mean score on the IIEF question about achieving erections rose from 2.0 to 4.0 out of a possible 5 | 24 |
| 25-100 mg, flexible | 69% of intercourse attempts successful vs 22% on placebo (final 4 weeks) | 12 |
| 25-100 mg, flexible | 5.9 successful attempts per month vs 1.5 on placebo | 12 |
Both studies were short (12 and 24 weeks) and relied on self-reported questionnaires and diaries, so they describe short-term effect rather than long-term outcomes.
NAMED SAFETY SIGNALS
What has been reported with Sildenafil.
Headache
Listed as very common in the EU product information — at least 1 in 10 men. In the pivotal trial, headache, flushing and dyspepsia were the most common effects, occurring in 6% to 18% of men.
Flushing
Listed as common in the EU product information — between 1 in 100 and 1 in 10 men.
Dyspepsia (indigestion)
Listed as common in the EU product information — between 1 in 100 and 1 in 10 men.
Nasal congestion
Listed as common in the EU product information — between 1 in 100 and 1 in 10 men.
Visual disturbance
Visual colour distortion, visual disturbance and blurred vision are listed as common in the EU product information. A dedicated study found mild, temporary blue/green colour-discrimination changes 1 hour after a 100 mg dose, with no effect remaining 2 hours after the dose.
Non-arteritic anterior ischaemic optic neuropathy (NAION)
Sudden loss of vision in one eye is listed as rare in the EU product information — between 1 in 10,000 and 1 in 1,000 men. Sildenafil is contraindicated in men who have already lost vision in one eye from NAION.
Use with nitrates
Contraindicated with nitrate medicines and nitric-oxide donors, because the combination can cause a serious drop in blood pressure.
€35 one-offStart a medical consultation
FormOral tablet
FrequencyOn demand
ResultsActs in 30–60 minutes
What you pay Hi-Doctor€35 one-off
IN 60 SECONDS
Sildenafil at a glance
- A PDE5-inhibitor tablet taken by mouth
- Adult men with erectile dysfunction; sexual stimulation is still required
- One tablet about an hour before sex, never more than one dose in 24 hours
- Nitrates and poppers are contraindicated: blood pressure can fall dangerously
- Hi-Doctor consultation fee; the medicine is paid separately at a pharmacy
About
What is Sildenafil?
Also sold as Viagra.
Active ingredient: Sildenafil · Dosages: 25 / 50 / 100 mg on demand
Sildenafil is a phosphodiesterase-5 (PDE5) inhibitor. It relaxes smooth muscle in the penile blood vessels, facilitating an erection in response to sexual stimulation — it does not cause spontaneous erections or change desire.
It's taken on demand, 30 to 60 minutes before sexual activity; high-fat meals can delay onset. The doctor prescribes the appropriate dose after reviewing your cardiovascular health, current medication and contraindications.
HOW IT WORKS
What Sildenafil does in your body
By inhibiting the PDE5 enzyme, sildenafil improves blood flow to the penis when there is sexual stimulation. Its effect starts within 30–60 minutes and lasts around 4–6 hours.
Arousal releases nitric oxide
During sexual stimulation, nerves and blood vessel linings in the penis release a gas called nitric oxide. Nitric oxide switches on an enzyme, guanylate cyclase, which makes a messenger chemical called cyclic GMP inside the erectile tissue.
Cyclic GMP lets blood in
Cyclic GMP relaxes the smooth muscle in the corpus cavernosum, the two spongy columns that run the length of the penis. As that muscle relaxes, blood flows in faster than it drains away, and the penis becomes firm.
Sildenafil blocks the PDE5 enzyme
Sildenafil is a selective blocker of phosphodiesterase type 5, the enzyme that breaks cyclic GMP down. With that enzyme blocked, cyclic GMP lasts longer and the natural response to arousal is stronger. Sildenafil does nothing on its own, so sexual stimulation is still required.
How it helps
How it helps.
Works on demand
Taken 30–60 minutes before sex — no daily routine required.
Adjustable dose
25, 50 or 100 mg — the doctor prescribes what fits your case and tolerance.
Doctor-screened
Cardiovascular health and interactions are reviewed before any prescription.
What to expect
How to take it.
On demand, before sexual activity. The doctor sets your dose and reviews it with you if the response or tolerance isn't right.
- Take it 30–60 minutes before sexual activity
- Avoid heavy, high-fat meals right before — they delay onset
- Never combine with nitrates
- Message your doctor to adjust the dose if needed
Doses your doctor can prescribe
- Available doses25 / 50 / 100 mg
- When30–60 min before activity
Your schedule is personal
These are typical steps only. Your doctor adjusts the plan to how you respond and tolerate it — and you can message them at any point.
DAY TO DAY
Taking Sildenafil day to day
Take it before sex
Swallow one tablet whole with a drink of water about one hour before sexual activity. The tablet does not cause an erection by itself, so you still need to feel sexually aroused for it to work.
Keep to one dose daily
Never take more than one dose in 24 hours. The usual dose is 50 mg and the maximum licensed dose is 100 mg. In volunteer studies 200 mg did not improve results but did increase side effects.
Expect it within the hour
In a study using a penile measuring device, the median time to an erection firm enough for sex was 25 minutes, with a range of 12 to 37 minutes. Effects can persist four to five hours.
Watch heavy meals
A meal slows absorption. With food, peak blood levels arrive about 60 minutes later and are roughly 29 percent lower, so the tablet may take longer to work. An empty stomach gives the fastest onset.
Go easy on alcohol
In healthy volunteers, sildenafil 50 mg did not add to the blood-pressure-lowering effect of alcohol at blood alcohol levels of about 80 mg per decilitre. The NHS still advises not drinking too much while taking it.
Skip the grapefruit juice
Swallow the tablet with water or juice, but not grapefruit juice. Grapefruit juice weakly blocks the same liver enzyme that clears sildenafil, so it can modestly raise the amount of the medicine in your blood.
Give it more than one try
Some men need to take sildenafil on several separate occasions before they get an erection good enough for sex. If several attempts do not help, or things get worse, tell the doctor rather than raising the dose yourself.
Book a medical review
Erection problems often sit alongside high blood pressure, diabetes, high cholesterol or heart disease. The product information advises every man with erectile dysfunction to see a doctor within six months to check for those underlying causes.
Safety first
Safety, in full.
Sildenafil is an effective medicine — and like any medicine it carries risks. Your doctor screens for all of this before prescribing. Here's the honest picture, not just reassurance.
Side effects, by how often they happen
Stop and get urgent medical help if
seek medical help immediately
these need urgent attention, whatever the frequency
- An erection that will not go down, especially past four hours, needs emergency treatment
- Sudden loss or blurring of vision in either eye: stop and get seen
- Sudden loss of hearing, with or without ringing: stop and seek help
- Chest pain during or after sex: call emergency services, and take no nitrates
- A seizure or fit: call emergency services
- Swelling of the lips, mouth, throat or tongue, or difficulty breathing: allergic reaction
- Peeling, blistering or widespread rash: possible severe skin reaction
Very common
very common (≥1/10)
more than 1 in 10 people
- Headache
Common
common (≥1/100 to <1/10)
between 1 in 100 and 1 in 10 people
- Dizziness
- A blue or otherwise altered tinge to colours you see
- Blurred vision or other changes to how you see
- Flushing of the face and neck
- Hot flushes
- A blocked or stuffy nose
- Feeling sick (nausea)
- Indigestion
Uncommon
uncommon (≥1/1,000 to <1/100)
between 1 in 1,000 and 1 in 100 people
- Runny nose, nosebleeds or sinus congestion
- Feeling sleepy, or reduced sensation in the skin
- Sore, red or watery eyes, or sensitivity to light
- Ringing in the ears (tinnitus) or a spinning feeling (vertigo)
- A fast or pounding heartbeat
- Raised or lowered blood pressure
- Vomiting, reflux, upper tummy pain or a dry mouth
- Skin rash, muscle aches, pain in an arm or leg, or tiredness
Rare
rare (≥1/10,000 to <1/1,000)
fewer than 1 in 1,000 people; many of these come from reports made after the medicine was licensed, and the EU label states their true frequency cannot be reliably determined
- Non-arteritic anterior ischaemic optic neuropathy (NAION), a sudden loss of vision
- Blockage or bleeding in the blood vessels of the retina, glaucoma or double vision
- Sudden deafness
- Priapism, an erection that will not go down, or bleeding from the penis
- Stroke, mini-stroke (TIA), fainting or a seizure
- Heart attack, unstable angina, irregular heartbeat or sudden cardiac death
- Severe skin reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis
- Throat tightness, swelling inside the nose or nasal dryness
Prescribed for adult men with erectile dysfunction. Taken about 30–60 minutes before sexual activity.
- Standard starting dose is 50 mg taken on demand, no more than once per day.
- Effect lasts up to 4 hours; sexual stimulation is still required for the medicine to work.
- A heavy or fatty meal can delay onset — taking it on a lighter stomach gives a more predictable response.
WHO SHOULD NOT TAKE IT, AND WHO NEEDS EXTRA CARE
- You take nitrates for chest pain, or any nitric oxide donor such as nicorandil or amyl nitrite ("poppers"), in any form
- You take riociguat or another guanylate cyclase stimulator for pulmonary hypertension
- You are already taking another PDE5 inhibitor or another erectile dysfunction treatment, because of the risk of severe low blood pressure and priapism
- You have ever had an allergic reaction to sildenafil or to any ingredient in the tablet
- A doctor has advised you against sexual activity, for example because of unstable angina or severe heart failure
- You have had a stroke or a heart attack recently
- Your blood pressure is low, below 90/50 mmHg
- You have severe liver problems
- You have an inherited degenerative eye disease such as retinitis pigmentosa
- You have lost the sight in one eye because of non-arteritic anterior ischaemic optic neuropathy (NAION)
When to seek urgent care
For severe, sudden or unexpected symptoms, call your local emergency number or go to the nearest emergency department. Then let your doctor know through your account chat.
Medicines and substances that interact
| MEDICINE OR SUBSTANCE | WHAT CAN HAPPEN | WHAT THE DOCTOR DOES |
|---|---|---|
| Nitrates and nitric oxide donors (GTN spray, isosorbide, nicorandil, amyl nitrite "poppers") | Sildenafil strongly amplifies their blood-pressure-lowering effect, which can cause collapse. | Contraindicated. The prescriber will not issue sildenafil while these are being used. |
| Riociguat and other guanylate cyclase stimulators | Adds to the blood-pressure fall, with no proven benefit from the combination. | Contraindicated. The prescriber selects a different treatment for erection problems. |
| Alpha-blockers (doxazosin, tamsulosin, alfuzosin) | Can cause dizziness or light-headedness on standing, usually within four hours of the dose. | Stabilise on the alpha-blocker first, then consider starting sildenafil at 25 mg. |
| Ritonavir | Raised sildenafil blood exposure about eleven-fold in a study of healthy volunteers. | Co-administration is not advised; if used at all, never above 25 mg in 48 hours. |
| Other CYP3A4 inhibitors (ketoconazole, itraconazole, erythromycin, cimetidine, saquinavir) | Slow sildenafil clearance; erythromycin raised exposure by 182 percent, cimetidine by 56 percent. | The prescriber considers a 25 mg starting dose. |
| Strong CYP3A4 inducers (rifampicin, bosentan) | Lower sildenafil levels; bosentan cut exposure by about 63 percent in volunteers. | The prescriber may adjust the dose or reconsider the choice of medicine. |
| Sacubitril/valsartan | Blood pressure fell significantly more than with sacubitril/valsartan alone in patients with hypertension. | Caution when starting sildenafil; the prescriber checks blood pressure. |
| Grapefruit juice | A weak inhibitor of gut-wall CYP3A4 that can modestly raise sildenafil blood levels. | Take the tablet with water rather than grapefruit juice. |
Have a doctor review your caseThis is exactly what the doctor screens for before prescribing anything.
Read the full Sildenafil safety summaryEVIDENCE
What the clinical trials found
Sildenafil's licensing evidence comes from the Sildenafil Study Group programme published by Goldstein and colleagues in the New England Journal of Medicine in 1998, together with the fixed-dose studies summarised in the EU product information.
329 men with erectile dysfunction · 12 weeks
Dose-escalation study, sildenafil versus placebo (P<0.001).
Source: Goldstein I, et al. Oral sildenafil in the treatment of erectile dysfunction (Sildenafil Study Group)329 men with erectile dysfunction · 12 weeks
Same dose-escalation study, sildenafil versus placebo (P<0.001).
Source: Goldstein I, et al. Oral sildenafil in the treatment of erectile dysfunction (Sildenafil Study Group)Men with erectile dysfunction
Fixed-dose studies in the EU product information; 25 percent reported improvement on placebo.
Source: Viagra 50 mg film-coated tablets: Summary of Product CharacteristicsMen with erectile dysfunction, dosed while fasting · Single dose
Penile plethysmography (RigiScan) study; range 12 to 37 minutes.
Source: Viagra 50 mg film-coated tablets: Summary of Product CharacteristicsMen with erectile dysfunction · Single dose
Separate RigiScan study; sexual stimulation was still needed to produce the response.
Source: Viagra 50 mg film-coated tablets: Summary of Product CharacteristicsIn plain terms, roughly seven in ten intercourse attempts worked on sildenafil in the pivotal trial, against roughly two in ten on a dummy tablet. Response rose with dose, from 62 percent of men reporting better erections on 25 mg to 82 percent on 100 mg. These are group averages from selected trial populations, so an individual man may do better, worse, or need a different dose, and the prescriber decides what is appropriate.
ALTERNATIVES
Sildenafil next to the other PDE5 inhibitors
| MEDICINE | HOW IT IS TAKEN | HOW OFTEN | TYPICAL DOSE RANGE | EU-AUTHORISED INDICATION | KEY EVIDENCE |
|---|---|---|---|---|---|
| Tadalafil | Tablet by mouth | As needed, or once daily | 2.5–20 mg | Treatment of erectile dysfunction in adult men; sexual stimulation is required. | 75% of intercourse attempts succeeded versus 32% on placebo |
| Vardenafil | Tablet by mouth | As needed, once daily maximum | 5–20 mg | Treatment of erectile dysfunction in adult men; sexual stimulation is required. | 80% achieved penetration on 20 mg versus 49% on placebo |
| Avanafil | Tablet by mouth | As needed, once daily maximum | 50–200 mg | Treatment of erectile dysfunction in adult men; sexual stimulation is required. | 58% of attempts succeeded on 100 mg versus 28% on placebo |
Not sure which one fits your case? The doctor reviews your history and tells you.
Start consultation · €35ACCESS AND COST
Getting Sildenafil, and what it costs
Across these ten countries sildenafil is normally a prescription-only medicine, with Ireland and Poland the exceptions, where specific sildenafil products are licensed for pharmacist supply without a prescription after a consultation. Where a national source confirmed it, the public health system does not pay for sildenafil used for erectile dysfunction, so the patient carries the cost; the entries left blank are ones we could not confirm from an official national source.
What you pay Hi-Doctor
€35 one-off
Answer a few questions and a licensed EU doctor reviews your case in less than 2 hours on average. Refunded in full if it's not right for you.
What the pharmacy charges
Hi-Doctor does not sell, stock or dispense medicines and does not set their price. The medicine is paid for separately at the pharmacy, and the amount depends on the country, the pack size, whether a generic is available and whether your health system covers it. The official national database linked in the table publishes the current authorised price.
| COUNTRY | HOW IT IS SUPPLIED | COVERED BY THE HEALTH SYSTEM? | OFFICIAL SOURCE |
|---|---|---|---|
| Spain | Prescription-only | — | AEMPS CIMA |
Show the other countries
| Germany | Prescription-only | Excluded from statutory health insurance | PharmNet.Bund AMIce |
|---|---|---|---|
| France | Prescription-only (liste I) | Not reimbursable (non remboursable) | Base de données publique des médicaments |
| Italy | Prescription-only (non-repeatable) | Not reimbursed (AIFA class C) | AIFA Medicinali |
| Netherlands | Prescription-only | Not reimbursed (niet vergoed) | CBG-MEB Geneesmiddeleninformatiebank |
| Portugal | Prescription-only (MSRM) | Reimbursement application refused | INFARMED Infomed |
| Belgium | Prescription-only | — | FAGG-AFMPS medicines database |
| Ireland | Prescription-only; a 50 mg pharmacy product is supplied without a prescription | — | HPRA Find a Medicine |
| Austria | Prescription-only | Not covered by statutory insurance | BASG Medikamente Info Austria |
| Poland | Prescription-only; 25 mg and 50 mg pharmacy products are supplied without a prescription | — | Rejestr Produktów Leczniczych |
PRICING
You only pay if treatment is approved.
€35 for one sexual-health consultation. Paid once, with no recurring charge.
Sexual health
ONE-OFF
€35 one-off
One consultation, one doctor, one decision.
Nothing stored publicly, ever
Start consultation
Full refund if a review is not approved
WHAT'S INCLUDED
- Consultation reviewed by an EU-licensed doctor
- Electronic prescription if approved
- Full refund if not approved
Full refund if a review is not approved
If a review is not approved, we refund the €35 consultation fee in full.
Note: The medication, if the doctor prescribes it, is paid separately at the pharmacy at the price it sets. Hi-Doctor does not sell medications.
HOW THE DOCTOR DECIDES
A licensed doctor reviews your case, not an algorithm
An EU-licensed doctor reads your questionnaire and answers in less than 2 hours on average.
If the doctor decides it is not safe to prescribe, the consultation fee is refunded in full.
Follow-up happens in the private chat inside your account, under GDPR. No WhatsApp, no SMS.
FREQUENTLY ASKED QUESTIONS
Questions about Sildenafil.
OTHER SEXUAL HEALTH TREATMENTS
Explore related treatments.
SOURCES
Where this information comes from
- 01
Viagra 50 mg film-coated tablets: Summary of Product Characteristics — electronic medicines compendium (emc), 2026
- 02
Viagra: EPAR product information (Annex I, Summary of Product Characteristics) — European Medicines Agency, 2026
- 03
Viagra: European public assessment report overview — European Medicines Agency, 2026
- 04
Goldstein I, et al. Oral sildenafil in the treatment of erectile dysfunction (Sildenafil Study Group) — New England Journal of Medicine, 1998
- 05
EAU Guidelines on Sexual and Reproductive Health, 2025 edition (PDE5 inhibitors first-line for erectile dysfunction, strong rating) — European Association of Urology, 2025
- 06
Sildenafil (Viagra): NHS medicines A to Z — NHS, 2022
- 07
Viagra Connect 50 mg film-coated tablets: Summary of Product Characteristics — electronic medicines compendium (emc), 2026
- 08
MHRA reclassifies Viagra Connect tablets to a Pharmacy medicine — Medicines and Healthcare products Regulatory Agency (GOV.UK), 2017
- 09
Cialis 20 mg film-coated tablets (tadalafil): Summary of Product Characteristics — electronic medicines compendium (emc), 2026
- 10
Vardenafil 20 mg film-coated tablets: Summary of Product Characteristics — electronic medicines compendium (emc), 2025
- 11
Spedra 100 mg tablets (avanafil): Summary of Product Characteristics — electronic medicines compendium (emc), 2024
- 12
CIMA: sildenafil records, prescription condition "Medicamento sujeto a prescripción médica" — Agencia Española de Medicamentos y Productos Sanitarios (AEMPS), 2026
- 13
Sozialgesetzbuch V, §34: medicines excluded from statutory provision, naming erectile dysfunction treatment — Bundesministerium der Justiz (gesetze-im-internet.de), 2026
- 14
VIAGRA 50 mg, comprimé pelliculé: liste I, "Prix libre, médicament non remboursable" — Base de données publique des médicaments (ANSM / Ministère de la Santé), 2026
- 15
Bollettino d'Informazione sui Farmaci: sildenafil (Viagra) non-repeatable prescription, all packs in fascia C — Agenzia Italiana del Farmaco (AIFA), 2000
- 16
Medicijnkosten: sildenafil 50 mg tablets listed as "niet vergoed" — Zorginstituut Nederland, 2026
- 17
Relatório de avaliação do pedido de comparticipação: Sildenafil Sandoz, indeferimento 19/07/2010 — INFARMED, I.P., 2010
- 18
Viagra Connect 50 mg film-coated tablet: authorised medicine record and pharmacy supply materials — Health Products Regulatory Authority (HPRA), Ireland, 2026
- 19
Rejestr Produktów Leczniczych: sildenafil products including Maxigra Go 25 mg and Viagra Connect Max 50 mg — Centrum e-Zdrowia, Poland, 2026
- 20
Die Grenzen des Krankenbehandlungsanspruchs am Beispiel der erektilen Dysfunktion (potency medicines on the negative list since April 2004) — Dachverband der österreichischen Sozialversicherungsträger, 2026
- 21
Gecommentarieerd Geneesmiddelenrepertorium: sildenafil oral, PDE5 inhibitors for erectile dysfunction — Belgisch Centrum voor Farmacotherapeutische Informatie (BCFI/CBIP), 2026
Reviewed by Hi-Doctor's medical team · Last reviewed 2026-07-27 · Next review due 2027-07-27
This page is educational information about a medicine, not a recommendation to take it and not a substitute for a medical consultation. Only a licensed doctor who has reviewed your history can decide whether a treatment is appropriate for you.
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