A long-acting PDE5 inhibitor
Tadalafil
A long-acting PDE5 inhibitor for erectile dysfunction — often called the "weekend pill" — that also eases prostate-related urinary symptoms; never combined with nitrates.
What is Tadalafil?
Tadalafil is a PDE5 inhibitor in the same family as sildenafil, used for erectile dysfunction and also for the urinary symptoms of an enlarged prostate. Its standout feature is how long it lasts, with effects that can carry over a day or more.
Education and reference only. This is a plain-language guide to Tadalafil — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tadalafil is a PDE5 inhibitor in the same family as sildenafil, but its standout feature is how long it lasts — its effect can carry over a couple of days, which is why it is sometimes nicknamed the "weekend pill". It is used for erectile dysfunction and, separately, to ease the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia), and some men with both problems are treated with a small daily amount. It is the active ingredient in Cialis; the same ingredient under the brand Adcirca is used for pulmonary hypertension (raised pressure in the lung arteries). Like all PDE5 inhibitors, it helps the physical erection only when arousal is present and does not boost desire.
How it works
During sexual arousal, the body releases a signal that relaxes the blood vessels of the penis so it fills with blood. An enzyme called PDE5 normally switches this signal off. Tadalafil blocks PDE5, letting the natural arousal response last longer and work better. Because tadalafil clears from the body slowly, its window of effect is much longer than sildenafil's — so sex does not have to be planned around a recent dose. The same relaxing effect on smooth muscle in the prostate and bladder neck is why it also helps urinary symptoms of an enlarged prostate.
Company & origin
Originated / developed by: ICOS / Eli Lilly.
Tadalafil, a PDE5 inhibitor, was developed by biotech company ICOS Corporation (USA) in partnership with Eli Lilly. It was first approved in Europe in 2002 and by the US FDA in 2003, marketed as Cialis (and Adcirca for pulmonary hypertension).
What it treats
Conditions Tadalafil is used for
Practical use
How to take Tadalafil
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Can be taken before sexual activity as needed, or as a regular low daily option that keeps it working continuously; it only works with sexual arousal.
- Its long-acting effect means timing is more flexible than with shorter-acting alternatives.
- Can be taken with or without food, as food has little effect on how it works.
- Never take it with nitrate medicines or recreational 'poppers', as this can cause a dangerous fall in blood pressure.
- Limit alcohol, which can make erections harder to achieve.
- Seek urgent medical help if an erection is painful or lasts several hours.
Weighing it up
Advantages & disadvantages of Tadalafil
Advantages
- Long-acting, giving more spontaneity, and available as an as-needed or daily option.
- Can treat both erectile dysfunction and enlarged-prostate urinary symptoms.
- Not significantly affected by food.
Disadvantages
- Can cause headache, flushing, indigestion, back pain and muscle aches.
- Must never be combined with nitrates because of the risk of a severe blood-pressure drop.
- Its long duration means side effects can also last longer.
- Not suitable for some men with certain heart conditions, so a check is needed first.
Practical use
Good to know
There are two patterns of use: an on-demand dose taken before sex, or a small amount taken every day that keeps a steady, low-key effect (handy for spontaneity, and the version used for prostate symptoms). Unlike sildenafil, food and a small amount of alcohol have little effect on how well it works. Its long duration is its main advantage over sildenafil, but it also means side effects such as muscle or back ache can linger longer. As with all of this class, a heart and circulation check first is sensible, because erectile difficulty can flag underlying vascular disease.
Who should not take it / use with caution
- Anyone taking nitrates for angina or chest pain (such as GTN, isosorbide mononitrate or dinitrate) or using nitrite "poppers" — the combination can cause a dangerous, sometimes fatal, fall in blood pressure. Because tadalafil lasts so long, this caution extends over a longer period.
- People who have recently had a heart attack or stroke, have very low blood pressure, or have certain inherited retinal eye diseases.
- Used with caution in men taking alpha-blockers for blood pressure or prostate symptoms, as both lower blood pressure; they are combined carefully and introduced gradually.
Monitoring
- Heart and circulation health before starting, especially alongside other heart medicines
- How well it works and whether daily or on-demand use suits you
- For prostate use, whether urinary symptoms improve
Side effects
- Headache, facial flushing, indigestion and a blocked nose are the most common.
- Back pain and muscle aches are more characteristic of tadalafil than of sildenafil, usually settling on their own.
- Rarely, a painful erection lasting more than 4 hours (priapism) — a medical emergency needing urgent care; sudden loss of vision or hearing also needs prompt review.
Key interactions
- Nitrates and nitrite "poppers" must never be combined with it — the most important interaction, and one that lasts longer because tadalafil stays in the body longer.
- Alpha-blockers and other blood-pressure medicines add to its effect, so they are introduced carefully to avoid dizziness or fainting.
- Some medicines (certain antifungals, some HIV and hepatitis-C treatments, and antibiotics like clarithromycin) raise its levels; grapefruit juice can do the same.
Available as: Tablets, available both as an on-demand strength and a small daily strength. Adcirca (the pulmonary-hypertension brand) is a separate tablet product.
Answers
Tadalafil: frequently asked questions
Why is tadalafil called the "weekend pill"?
Because it lasts much longer than sildenafil — its effect can span a couple of days — so sex does not have to be timed closely around a dose. This makes it feel more spontaneous. The trade-off is that any side effects, such as back ache, can also last a bit longer.
Should I take it every day or only before sex?
Both are options. Some men take a dose on demand before sex; others take a small amount every day for a steady effect and more spontaneity. The daily version is also the one used to ease the urinary symptoms of an enlarged prostate. Your prescriber will help match the pattern to your needs.
Can tadalafil really help my waterworks as well?
Yes. Tadalafil relaxes smooth muscle in the prostate and bladder neck, which can ease the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia) — useful for men who have both prostate symptoms and erectile difficulty, as one medicine can address both.
Is it safe with my blood-pressure tablets?
It can be, but with care. Tadalafil itself lowers blood pressure a little, and alpha-blockers (often used for blood pressure or prostate symptoms) do too, so the combination can cause dizziness and is introduced gradually. Crucially, it must never be combined with nitrate medicines. Tell your prescriber every medicine you take.
What is the difference between tadalafil and Cialis?
They are the same medicine — tadalafil is the generic (active-ingredient) name and Cialis is the original brand. Generic tadalafil contains the identical active ingredient, works the same way, and is usually far cheaper. Adcirca is the same ingredient sold for a different condition (lung-artery pressure).
The wider class
About PDE5 inhibitors
Tadalafil belongs to the pde5 inhibitors class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF: Tadalafil.
- electronic Medicines Compendium (SmPC): Tadalafil (Cialis/Adcirca).
- NICE CKS: Tadalafil (Cialis).
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