Tadalafil Uses: What It Treats and How It Works
What tadalafil is prescribed for, how it works, how long it lasts, and how the daily and as-needed doses differ — reviewed by UK clinicians.
▶ In short — What is tadalafil used for?
Tadalafil is used to treat erectile dysfunction (ED) and the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia). It is the active ingredient in Cialis and works for up to 36 hours — far longer than sildenafil — and is also available as a low daily dose (2.5mg or 5mg) for men who prefer not to plan around a tablet.
Part of the Erectile Dysfunction Treatment Guide.
What Is Tadalafil Used For?
Tadalafil belongs to a group of medicines called PDE5 inhibitors (phosphodiesterase type 5 inhibitors). In the UK it is licensed for three related conditions:
- Erectile dysfunction (ED) — the main use. Taken either as needed before sex, or as a low daily dose, tadalafil helps men get and keep an erection firm enough for intercourse. This is the use most people know as Cialis.
- Benign prostatic hyperplasia (BPH) — tadalafil 5mg once daily is licensed to relieve the urinary symptoms of an enlarged prostate, such as a weak stream, urgency and getting up at night to urinate. It can treat BPH and ED at the same time.
- Pulmonary arterial hypertension (PAH) — under the brand name Adcirca, tadalafil is used at a different dose to relax blood vessels in the lungs. This is a specialist hospital use, not covered here.
This guide focuses on tadalafil for erectile dysfunction and for an enlarged prostate — the two uses most men are prescribed it for.
Diagnosis first: ED can be an early warning sign of cardiovascular disease, diabetes or low testosterone. If erection problems are new or persistent, it is worth having your blood pressure, blood sugar and cholesterol checked rather than only treating the symptom.
How Does Tadalafil Work?
An erection is a blood-flow event. During arousal, nerves in the penis release nitric oxide, which triggers a messenger chemical called cGMP. cGMP relaxes the smooth muscle in the walls of the penile arteries, letting blood flow in and become trapped in the erectile tissue. An enzyme called PDE5 constantly breaks cGMP down — in many men with ED, faster than it can build up.
Tadalafil works by blocking PDE5. With the enzyme inhibited, cGMP levels stay higher for longer, blood vessels stay relaxed, and the natural erection response becomes stronger and easier to maintain. The same muscle-relaxing effect on the prostate and bladder neck is what eases the urinary symptoms of an enlarged prostate.
Important: tadalafil enhances the body's natural response to arousal — it does not create an erection automatically, and it has no effect on sex drive.
The 36-Hour Window: How Long Tadalafil Lasts
Tadalafil's stand-out feature is how long it lasts. A single as-needed dose can keep working for up to 36 hours, compared with around 4 hours for sildenafil — which is why it's nicknamed "the weekend pill". It usually starts working within 30 to 120 minutes, and unlike sildenafil it is not significantly affected by food, so you don't need to take it on an empty stomach.
30–120
minutes for tadalafil to start working
36 hrs
how long a single dose can last
Any
time — food does not significantly affect it
The long window is why many men prefer tadalafil: it removes the pressure to time a tablet closely before sex, allowing for more spontaneity across a weekend or a couple of days. Arousal is still needed for it to work.
Tadalafil Doses: Daily vs As-Needed
Tadalafil for ED comes in two approaches — and choosing between them is really about how often you have sex and whether you'd rather plan or be ready anytime.
| Approach | Doses | Best for |
|---|---|---|
| As-needed | 10mg or 20mg, taken before sex (max one dose per day) | Men who have sex less often and prefer to take a tablet when needed — making use of the 36-hour window |
| Daily | 2.5mg or 5mg, taken once every day at the same time | Men who have sex twice a week or more, want spontaneity, or also have urinary symptoms from an enlarged prostate |
With the daily dose, tadalafil builds to a steady level in the body so you're ready at any time without planning. The usual starting point for as-needed use is 10mg, adjusted up to 20mg or down to 5mg depending on how well it works and how well you tolerate it. Whatever the approach, side effects are generally mild — most commonly headache, flushing, indigestion, back pain and a blocked nose.
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Order Tadalafil →Tadalafil for an Enlarged Prostate (BPH)
This is where tadalafil does something sildenafil can't. Tadalafil 5mg once daily is licensed to treat the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia) — a common condition in older men where the prostate presses on the urethra.
By relaxing smooth muscle in the prostate and bladder neck, tadalafil eases symptoms such as:
- A weak or slow urine stream
- A sudden or frequent urge to urinate
- Getting up at night to pass urine (nocturia)
- A feeling of not fully emptying the bladder
Because the same 5mg daily dose treats both, tadalafil is a practical choice for men who have erectile dysfunction and an enlarged prostate — one tablet covers both. If your main problem is urinary symptoms, your GP may still recommend assessment to rule out other causes before treating.
Who Shouldn't Take Tadalafil?
Tadalafil is safe for most men, but there are situations where it must not be taken and others where it needs extra care. This is why a clinical assessment is required before every prescription.
Never take tadalafil with nitrates. This includes GTN sprays and tablets, isosorbide mononitrate or dinitrate, and recreational "poppers" (amyl or butyl nitrite). Combining them can cause a sudden, dangerous drop in blood pressure. The same applies to riociguat, a medicine for pulmonary hypertension.
Do not take tadalafil if you:
- Take nitrates in any form, or use poppers
- Have severe heart or liver problems, or have been told sexual activity is unsafe for your heart
- Have had a recent stroke or heart attack (generally within the last 3–6 months)
- Have very low blood pressure, or uncontrolled high blood pressure
- Have ever lost vision because of non-arteritic anterior ischaemic optic neuropathy (NAION)
Take extra care (tell your prescriber) if you:
- Take an alpha-blocker for your prostate or blood pressure (doxazosin, tamsulosin) — doses may need adjusting
- Take medicines for high blood pressure, or strong CYP3A4 inhibitors such as ritonavir, ketoconazole or clarithromycin
- Have a deformity of the penis (such as Peyronie's disease), sickle cell disease, leukaemia or multiple myeloma — these raise the risk of priapism
Seek emergency help if you have an erection lasting more than 4 hours (priapism), sudden loss of vision or hearing, or chest pain during or after sex. Call 999 or go to A&E.
Tadalafil vs Sildenafil: Which Should You Choose?
Both work the same way and are similarly effective — the difference is timing. Tadalafil lasts up to 36 hours and comes as a daily option; sildenafil lasts around 4 hours and is taken as needed. Tadalafil suits spontaneity and men who also have prostate symptoms; sildenafil suits planned, occasional use and is the lowest-cost option.
| Tadalafil (Cialis) | Sildenafil (Viagra) | |
|---|---|---|
| How long it lasts | Up to 36 hours | Up to 4 hours |
| Time to work | 30–120 minutes | 30–60 minutes |
| Food effect | Largely unaffected by food | Heavy meals delay and weaken it |
| Daily option | Yes — 2.5mg/5mg once daily | No — as-needed only |
| Also treats BPH | Yes (5mg daily) | No |
| Typical cost | Inexpensive as a generic | Lowest-cost ED tablet |
You can order sildenafil online through the same consultation, and our sildenafil uses guide covers that medicine in the same depth. If climaxing too quickly is also a concern, note that tadalafil does not treat this — see our premature ejaculation treatment page instead.
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Start Your Consultation →Frequently Asked Questions
Is tadalafil the same as Cialis?
Yes, in terms of the medicine. Tadalafil is the active ingredient in Cialis. Generic tadalafil contains the same drug at the same doses and works in exactly the same way — the main differences are the name on the packet and the price, with generic tadalafil typically costing far less.
How long does tadalafil last?
Tadalafil can work for up to 36 hours from a single dose, which is why it is nicknamed "the weekend pill". This is much longer than sildenafil (around 4 hours). It usually starts working within 30 to 120 minutes and is not significantly affected by food.
Can I take tadalafil every day?
Yes — tadalafil is available as a low daily dose (2.5mg or 5mg) taken once a day, as well as an as-needed dose (10mg or 20mg). The daily option suits men who want to be ready without planning around a tablet, and is also used to treat the urinary symptoms of an enlarged prostate. Your prescriber will advise which is right for you.
Does tadalafil work better than sildenafil?
Neither is "better" — head-to-head studies show similar effectiveness. The main difference is duration: tadalafil lasts up to 36 hours versus around 4 hours for sildenafil, so tadalafil suits spontaneity and a daily routine, while sildenafil suits planned, occasional use. The best choice comes down to how you prefer to plan sex.
Can tadalafil help with an enlarged prostate?
Yes. Tadalafil 5mg once daily is licensed to treat the urinary symptoms of benign prostatic hyperplasia (BPH) — such as a weak stream, urgency and needing to urinate at night — and can treat these symptoms and erectile dysfunction at the same time. It relaxes smooth muscle in the prostate and bladder, easing the flow of urine.
Getting tadalafil through Access Doctor is straightforward: complete a confidential online consultation, and a GPhC-registered pharmacist independent prescriber will check the medicine is safe for you before it is dispensed and posted in plain packaging. If tadalafil isn't the right fit, shorter-acting sildenafil is available through the same process.
Erectile Dysfunction · Rx
Tadalafil
The long-lasting ED tablet — up to 36 hours per dose, with a daily option that also treats prostate symptoms.
View product →Erectile Dysfunction · Rx
Sildenafil
The UK's most prescribed ED tablet. Works in 30–60 minutes, lasts up to 4 hours.
View product →References
- NHS. Tadalafil (Cialis): a medicine to treat erection problems and prostate problems. nhs.uk
- NICE. British National Formulary: Tadalafil. bnf.nice.org.uk
- NICE. Clinical Knowledge Summary: Erectile dysfunction. cks.nice.org.uk
- Electronic Medicines Compendium. Tadalafil 5mg / 20mg film-coated tablets: Summary of Product Characteristics. medicines.org.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment. Tadalafil is a prescription-only medicine — a clinical assessment is required before it can be supplied. In a medical emergency, call 999.