Sildenafil treatment guide
Everything you need to know about sildenafil: how to take it, what to expect, managing side effects, and when to contact your doctor.
Sildenafil treatment guide
Everything you need to know about sildenafil: how to take it, what to expect, managing side effects, and when to contact your doctor.
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- 2 min read
- PATHWAY
- Fast-acting PDE5 (Sildenafil) 25/50/100mg
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How to use
- Take 30-60 minutes before activity
Take one tablet approximately 30-60 minutes before sexual activity. The effect lasts about 4 hours. Do not take more than one dose per day.
- On an empty stomach works best
A heavy or fatty meal may delay the onset of action. Taking it on an empty stomach or after a light meal gives the most reliable effect.
- Sexual stimulation is needed
Sildenafil works in response to sexual arousal. It does not cause an automatic erection: you need to be sexually stimulated for it to work.
Before you start. Tell the medical team about any heart condition, chest pain, recent stroke or heart attack, and every blood-pressure medicine you take. Never use with nitrates (including glyceryl trinitrate sprays or patches) or riociguat: the combination can cause a dangerous drop in blood pressure. Mention alpha-blockers (for prostate or blood pressure): the starting dose may need to be lower.
While on treatment. If the first dose gives a weaker result than expected, try it on up to 8 separate occasions before judging: response commonly improves with use. Report dizziness, fainting, chest pain during sex, or any visual or hearing change immediately. An erection lasting more than 4 hours (priapism) is an emergency: seek immediate care to protect long-term function.
Treatment pathway
See the full decision pathway
Your sildenafil pathway
First doses
Take about 1 hour before sex
The usual starting dose is 50 mg. Sexual stimulation is still required: the tablet enables, it does not initiate.
- Heavy or fatty meals and alcohol slow it down
- Maximum one dose in 24 hours
After up to 8 attempts at the current dose, is the response satisfactory?
Yes
Stay at this dose
Use as needed, never more than once daily.
No
Doctor review
The dose can be adjusted (25-100 mg) or switched to a longer-acting option like tadalafil.
First doses
Chest pain during sex, fainting, vision or hearing changes, or an erection over 4 hours need immediate medical attention.
Dose schedule
- As needed
Take one tablet 30-60 minutes before sexual activity. Available strengths: 25 mg, 50 mg, 100 mg. Your doctor will recommend the right dose for you.
How it compares
| PDE5 inhibitors compared | Starts working | Lasts | Food interaction | Dosing |
|---|---|---|---|---|
| Sildenafil | 30-60 minutes | About 4-5 hours | Slower after heavy or fatty meals | As needed, max once daily |
| Tadalafil | Within 30 minutes to 2 hours | Up to 36 hours | Not affected by food | As needed, or low dose once daily |
| Vardenafil | 25-60 minutes | About 4-5 hours | Slower after fatty meals | As needed, max once daily |
| Avanafil (Spedra) | 15-30 minutes | About 6 hours | Slightly slower after food | As needed, max once daily |
All PDE5 inhibitors require sexual stimulation to work and share the same absolute rule: never combine with nitrates or riociguat.
Side effects
Common side effects
Headache, facial flushing, nasal congestion, indigestion, or mild dizziness. These are usually mild and temporary.
When to seek medical help
If you experience sudden vision loss, hearing loss, chest pain, or an erection lasting more than 4 hours (priapism), stop taking the medication and seek emergency medical attention immediately.
Do not use if
- Any nitrate medicine (glyceryl trinitrate, isosorbide) or riociguat: this combination can be life-threatening
- Recent heart attack or stroke, or heart problems that make sexual activity inadvisable
- Severe liver impairment or very low blood pressure
- A previous non-arteritic ischaemic optic neuropathy (sudden vision loss)
- Hereditary degenerative retinal disorders such as retinitis pigmentosa
- Allergy to sildenafil or any tablet ingredient
- Recreational 'poppers' (amyl nitrite): same dangerous interaction as nitrates
This list is not exhaustive: your questionnaire and prescriber review decide whether sildenafil is safe for you.
When to contact your doctor
- Erections lasting more than 4 hours
- Sudden vision or hearing changes
- Chest pain or shortness of breath during sexual activity
- The medication does not work for you
Storage
Store at room temperature below 25°C. Keep in the original packaging to protect from light and moisture. Do not use after the expiry date on the carton.
What to expect
Sildenafil is a PDE5 inhibitor that increases blood flow to the penis in response to sexual stimulation. It is taken as needed, not daily. The effects start within 30-60 minutes and last around 4 hours. It is effective in approximately 70-80% of men. If the first dose does not work well, your doctor may adjust the strength.
Sources
Questions while you're on treatment?
Message your doctor in your private chat about side effects, doses or anything that worries you. Replies in under 2 hours on average.
- Discreet follow-up in the private chat
- Download your e-prescription
- Renewals reviewed by your doctor
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