First things first: none of these tablets can be taken with nitrates for the heart, and all four are prescription-only in Spain. In Spain, prescription-only medicines may not be sold online, and customs can hold a parcel that contains them. We do not check prescriptions: talk to your doctor before you order.

If you have moved to Madrid, the name on the box may be the only familiar thing at the pharmacy counter. Viagra and Cialis are sold under the same names here. Levitra has all but vanished from Spanish shelves, replaced by generic vardenafil, and avanafil is sold as Spedra (Americans may know it as Stendra). Spanish generics carry the letters EFG on the pack.

All four work the same way: they block an enzyme called PDE5 so that sexual arousal can lead to an erection. Without arousal, nothing happens. What separates them is timing, how food affects them and which side effects they tend to cause. The figures on this page come from the Spanish product information (the ficha técnica) that the medicines agency AEMPS publishes in its CIMA database.

The four at a glance

	Sildenafil	Tadalafil	Vardenafil	Avanafil
On sale in Spain	Viagra 25, 50 and 100 mg; dozens of generics, some chewable	Cialis 5, 10 and 20 mg; generics, including melt-in-the-mouth tablets	Mostly generics (5, 10, 20 mg; 10 mg melt tablets); Levitra only as a parallel import, 20 mg	Spedra 50, 100 and 200 mg; no generics
Starting dose / maximum	50 mg / 100 mg	10 mg / 20 mg, or 5 mg daily	10 mg / 20 mg	100 mg / 200 mg
When to take it	About an hour before	At least 30 minutes before	25 to 60 minutes before	15 to 30 minutes before
Shown to work up to	4 to 5 hours in one study	36 hours	4 to 5 hours, in the few men who tried	No time limit given in the ficha
After a meal	Can kick in about an hour later	Food makes no difference	Only a very fatty meal delays it (about an hour)	A fatty meal delays it by over an hour
Side effects people notice	Headache, flushing, a blue or green tinge to colours	Headache, indigestion, back and muscle ache	Headache, flushing, stuffy nose; slightly lengthens the QT interval	Headache, hot flushes, blocked nose, lower back pain

None of them may be taken more than once a day. Each was tested against a placebo rather than against the others, so there is no official answer to “which one is strongest”.

What usually tips the balance

Eating out, Madrid-style

Dinner at ten is normal here, and it is rarely light. Taken on a full stomach, sildenafil reaches its peak about an hour later than usual, and a fatty meal holds avanafil back by a little over an hour. Vardenafil only slows down after a very fatty meal. Tadalafil is not affected by food at all, which makes it the easiest of the four to fit around a long dinner.

Weekends without a stopwatch

In trials, tadalafil still worked better than placebo 36 hours after the dose. For men who expect to use it at least twice a week, the ficha also allows 5 mg once a day at roughly the same time, with the doctor checking every so often that it is still the right choice. A 2.5 mg daily dose exists on paper, but no 2.5 mg pack is currently marketed in Spain according to CIMA.

Short notice

Avanafil is the one you take closest to the moment, 15 to 30 minutes ahead. Vardenafil needs 25 to 60 minutes, sildenafil about an hour and tadalafil at least half an hour.

Side effects you already know about

Headache, flushing and a stuffy nose can happen with any of the four. The differences: sildenafil can briefly give colours a blue or green cast; tadalafil often causes back pain and aching muscles; vardenafil slightly prolongs the QT interval on an ECG, so it is avoided by men with a long QT or on certain heart-rhythm drugs. The avanafil leaflet specifically warns that alcohol raises the chance of low blood pressure and dizziness.

Everything else in your medicine cabinet

Nitrates (GTN spray or tablets under the tongue, isosorbide mononitrate, nitrate patches) and riociguat rule out all four. If you ever need a nitrate in an emergency, tell whoever treats you what you took and when: the tadalafil ficha asks for a gap of at least 48 hours, and the avanafil one flags the first 12 hours. Alpha-blockers for the prostate, such as tamsulosin or doxazosin, can drop your blood pressure too. The tadalafil ficha advises against combining it with doxazosin and, with any other alpha-blocker, asks for caution, particularly in older men, and a start on the lowest dose. Vardenafil should start at 5 mg. Some antibiotics and HIV drugs (clarithromycin, ritonavir) mean a lower dose or a different medicine, and grapefruit matters as well, above all with vardenafil and avanafil.

None of the four is advised after a recent heart attack or stroke, with blood pressure below 90/50 mmHg, with unstable angina, or if you have lost the sight of one eye to a condition called NAION.

From health card to urologist: the Madrid route

If you are in the public system. The Comunidad de Madrid issues a tarjeta sanitaria (health card) to residents whose right to public healthcare has been recognised by the Social Security institute, INSS: people working and paying contributions, pensioners, and EU citizens who have transferred their cover from home, for example with an S1 form. You apply at the centro de salud (health centre) for your address, where you are given a GP, the médico de familia. That GP can prescribe any of these tablets and, if needed, refer you to Urología. Under Madrid's free choice scheme, when the appointments centre rings you about that first visit you can ask for a particular hospital or specialist among those offered. The health card page lists who qualifies.

If you are only here for a while. The European Health Insurance Card (EHIC, TSE in Spanish) covers care you need during a temporary stay. It is not a substitute for registering once you actually live here.

If you have private insurance. A prescription written by a private doctor in Spain is valid in any Spanish pharmacy. Whether the consultation is covered depends on your policy.

If you bring a prescription from home. Spanish pharmacies recognise prescriptions issued in other EU countries, provided they show your full name and date of birth, the date, the prescriber's name, qualification, professional address, country, direct contact details and signature, and the medicine's name, form, strength, quantity and dosage. The pharmacist may refuse if there are reasonable doubts about it being genuine, Spanish rules (including generic substitution) still apply, and you pay the full price. Those rules cover EU prescriptions only. Spanish pharmacies are not obliged to accept a UK prescription; some pharmacists may, at their discretion. With one from the US or elsewhere, plan on seeing a doctor here.

Whichever route you take, expect to pay for the tablets yourself: in the Health Ministry's BIFIMED database, Viagra, Cialis, Spedra and generic vardenafil are all listed as not funded by the public system.

Out of hours, look for a farmacia de guardia (duty pharmacy). The Madrid pharmacists' college, the Colegio Oficial de Farmacéuticos de Madrid, has a pharmacy finder in Spanish, and the city council publishes the duty rota for the city on its open data portal, using the college's data. The rota changes daily, so look it up on the day.

Call 112 if, after taking any of these tablets, you get chest pain, feel faint or pass out, or suddenly lose sight or hearing. An erection lasting 4 hours or more is also an emergency. For a possible overdose, Spain's poisons information service (Servicio de Información Toxicológica) answers on 91 562 04 20.

No shop to walk into

There's no shop or pharmacy of ours in Madrid, and we don't sell face to face. Orders go out by post or courier. Our delivery conditions page has the details; we don't quote delivery times here because they depend on the carrier. And as the box at the top says, customs can hold a parcel, and nobody on our side checks for a prescription.

What this site sells, described plainly

We don't sell avanafil. Spedra is only available from a pharmacy, on prescription.

Questions expats in Madrid ask us

Sources: Spanish product information (fichas técnicas) for Viagra, Cialis, Levitra and Spedra and the CIMA medicines register (AEMPS); the Health Ministry's BIFIMED funding database; Comunidad de Madrid pages on the health card, free choice of doctor and hospital urology departments; Ministry of Health guidance on prescriptions from other EU countries; Colegio Oficial de Farmacéuticos de Madrid. This page is for information and does not replace a consultation. In Spain, prescription-only medicines may not be sold online, and customs can hold a parcel that contains them. We do not check prescriptions: talk to your doctor before you order.

Viagra, Cialis or something else? Choosing an ED pill in Madrid