01 / The basics
What is Viagra?
Viagra contains sildenafil and is used for erectile dysfunction in adult men. It belongs to the PDE5 inhibitor class. Sexual stimulation is required; the medicine supports an erection response rather than creating sexual desire.
By slowing the breakdown of cGMP, sildenafil helps the smooth muscle in penile erectile tissue relax and supports blood flow. Viagra is a brand; generic sildenafil is the ingredient name, not the same brand.
Sources:
EMA ↗
Sildenafil is also used under other brands and regimens for pulmonary arterial hypertension. Those treatment schedules are not interchangeable with Viagra use for erectile dysfunction. It does not prevent pregnancy or sexually transmitted infections.
Sources:
MedlinePlus ↗
02 / Use
&
dosage
How is it used?
Approved product information describes 50 mg as needed, approximately one hour before sexual activity. A clinician may reduce it to 25 mg or increase it to a maximum of 100 mg according to response and tolerability. The usual maximum frequency is once per day; some patients need less frequent dosing.
25 mg
Lower strength
50 mg
Label starting dose
100 mg
Label maximum dose
This is educational information, not a dose recommendation. Age, kidney or liver function and interacting medicines may change the appropriate dose. Follow your prescription and your local pack leaflet.
Sources:
EMA ↗
·
Pfizer ↗
Swallow film-coated tablets with water. A high-fat meal can delay the onset. Do not take extra tablets because an effect seems slow, and do not combine it with another erectile dysfunction medicine on your own.
Sources:
MedlinePlus ↗
·
EMA ↗
03 / Effect
&
timing
Timing is a window, not a guarantee.
US product information allows use from 30 minutes to 4 hours before sexual activity, with about one hour as the usual timing. That is a dosing window, not a promise of a continuous erection.
Sources:
Pfizer ↗
A study of onset and duration assessed erectile response with sexual stimulation, including testing four hours after dosing. Results from selected study participants cannot predict your exact onset or duration.
Sources:
PubMed ↗
If treatment is not helping, discuss the timing, diagnosis and other medicines with a clinician. Increasing the dose yourself is not an appropriate response.
04 / Possible side effects
Know what to watch for.
Not everyone has side effects. Commonly reported effects include:
Headache
Flushing
Indigestion
Blocked nose
Dizziness
Nausea
Visual changes
Ask a doctor or pharmacist about persistent or troublesome symptoms. This list is incomplete; read the full leaflet. Sudden loss of sight is different from a mild visual change and requires urgent care.
Sources:
NHS ↗
·
EMA ↗
Get urgent help
An erection lasting 4 hours or longer, sudden vision or hearing loss, chest pain or a severe allergic reaction require urgent medical assessment. Stop use and seek help. In an emergency, call your local emergency number.
Do not take nitrate medicines yourself for chest pain after sildenafil. Tell emergency staff when you last took it.
Sources:
NHS ↗
·
EMA ↗
05 / Before taking it
Safety starts with interactions.
Never combine sildenafil with nitrates or riociguat.
A dangerous fall in blood pressure can occur. Nitrite-containing “poppers” are also unsafe.
Alpha-blockers, blood pressure medicines and strong CYP3A4 inhibitors such as ritonavir or ketoconazole can affect safety. Tell your clinician about every medicine and supplement, including other sildenafil products.
Heart disease, low blood pressure, recent stroke or heart attack, serious liver or kidney problems and certain eye conditions need medical review. If sexual activity is medically inadvisable, Viagra must not be used.
Sources:
EMA ↗
·
MedlinePlus ↗
A medicine pack’s leaflet contains the full restrictions and warnings. This summary does not establish whether Viagra is suitable for you.