What these medicines do — and do not
Sildenafil and its cousins (tadalafil, vardenafil, avanafil) belong to one family, the PDE5 inhibitors. They stop the breakdown of a molecule that lets the arteries of the penis relax: blood flows in better, the erection comes and holds.
What they do not do, and this is the source of most disappointment: they do not create desire. Without arousal, nothing happens. A man who no longer wants to will not get an erection by swallowing a tablet — he will only get a headache. Nor do they treat the cause: they compensate, for the length of an encounter.
The differences between molecules are mostly about duration. Sildenafil works for about four hours and tolerates a fatty meal poorly, which delays it. Tadalafil covers up to thirty-six hours, which removes the need to schedule the moment — often what couples value most.
The real dangers
Nitrates: the combination that kills
Combined with glyceryl trinitrate or any other nitrate — taken for angina, as a tablet, spray or patch — PDE5 inhibitors cause a sudden drop in blood pressure that can be fatal. It is an absolute contraindication, with no exception and no sensible safety interval. Poppers, which are nitrites, fall under the same ban.
Other cautions matter too: a recent heart attack or stroke, very low blood pressure, unstable heart failure, certain inherited retinal diseases. Common side effects — headache, flushing, blocked nose, passing visual disturbance — are mild. A painful erection lasting more than four hours, by contrast, is an emergency: it can permanently damage the tissue, and it means going to hospital, not waiting it out.
One point is rarely made: the symptom is often a signal. Erectile dysfunction that settles in sometimes announces vascular disease or diabetes before any other sign. Skipping the consultation means skipping that screening.
Where can you get it without a prescription?
Almost nowhere. Four countries have opened a route without a doctor's prescription, always through a pharmacy consultation:
United Kingdom, since 2018: sildenafil 50 mg as Viagra
Connect, after speaking to the pharmacist.
Poland, since May 2016.
New Zealand, since 2014: through a specifically trained
pharmacist, and only for men aged 35 to 70.
Norway, since August 2019.
Everywhere else a prescription remains compulsory for every PDE5 inhibitor. Two practical consequences. A site offering you sildenafil "from the UK" is not thereby allowed to ship it to you: the rule that applies is the one where you live. And in many countries a prescription can now be obtained by remote consultation without travelling — quicker than looking for a way round.
Buying online: the real risk
This is the most active counterfeit market in the whole of pharmacy. Analyses of seizures regularly find tablets with no active ingredient, doses several times the label, and additions that have no business being there: antidiabetics, industrial dyes, amphetamines. The problem is not only the product but the absence of any examination: buying online means skipping the cardiovascular work-up that would have found the hypertension or diabetes behind the symptom.
The warning signs are consistent: no prescription asked for where your country requires one, no verifiable physical address, payment by transfer or cryptocurrency, a price well below the generic in a pharmacy. Legal online pharmacies, by contrast, are listed by each country's health authority and display an official clickable logo linking back to that register.
What it changes in a couple
Two pitfalls recur. The first is secrecy: many men take the tablet without saying so, which adds a tension to the one they were trying to solve, and leaves the partner without an explanation when the erection suddenly returns. The second is narrowing: when the tablet becomes the condition of every encounter, the couple loses the rest — the touching, the slowness, what existed before the symptom. Practitioners repeat it: the medicine works better added to a sex life, and less well replacing one.