Tadalafil: Uses, Dosage, Side Effects and How to Get It in the UK
What tadalafil treats, how it works, as-needed and daily doses, side effects, who should not take it, and how to get it safely in the UK — reviewed by UK clinicians.
When to get urgent help: Call 999 if you get chest pain during or after sex (tell the paramedics you have taken tadalafil, as nitrates such as GTN must not be given), or signs of a serious allergic reaction. Go to A&E straight away if an erection is painful or lasts more than 2 hours (do not drive yourself). Stop tadalafil and go to A&E straight away if you have a sudden decrease or loss of vision or hearing. See your GP about new erection problems or urinary symptoms, as they can be signs of other health conditions.
Part of the Erectile Dysfunction Guides.
Key fact: Tadalafil (the active ingredient in Cialis) treats erectile dysfunction and the urinary symptoms of an enlarged prostate. A single dose can work for up to 36 hours, food does not affect it, and it is the only ED tablet also licensed as a low daily dose. It must never be taken with nitrates or “poppers”.
Tadalafil Online — As-Needed or Daily
Access Doctor provides tadalafil following a GPhC-regulated online consultation with our pharmacist independent prescribers, who check it is safe for you and recommend the right dose.
Order Tadalafil →What is tadalafil and what is it used for?
Tadalafil belongs to a group of medicines called PDE5 inhibitors (phosphodiesterase type 5 inhibitors), the same group as sildenafil (Viagra), vardenafil (Levitra) and avanafil (Spedra). See our comparison of Viagra, Cialis, Levitra and Spedra. It was first sold as Cialis and is now widely available as a much cheaper generic, which contains the same medicine and works in the same way.
In the UK, tadalafil is licensed for:
- Erectile dysfunction (ED) — the main use, taken either as needed before sex or as a low dose every day.
- Enlarged prostate (benign prostatic hyperplasia, BPH) — tadalafil 5mg once a day is licensed to relieve urinary symptoms such as a weak stream, urgency and getting up at night to pass urine. It can treat BPH and ED at the same time.
- Pulmonary arterial hypertension (PAH) — a separate, specialist-prescribed use at a different dose (for example as Adcirca). It is not covered in this guide.
Get checked as well as treated: erection problems can be an early sign of heart disease, high blood pressure, diabetes or low testosterone. Even if tadalafil works for you, see your GP for a review including blood pressure, blood sugar and cholesterol.
How does tadalafil work?
An erection depends on blood flow. During arousal, nerves in the penis release nitric oxide, which triggers production of a messenger chemical called cGMP. cGMP relaxes the muscle in the walls of the penile blood vessels so blood can flow in. An enzyme called PDE5 breaks cGMP down. Tadalafil blocks PDE5, so cGMP stays higher for longer and the natural erection response is stronger and easier to keep. The same muscle-relaxing effect in the prostate and bladder neck eases the urinary symptoms of an enlarged prostate.
Important: tadalafil improves the body’s natural response to arousal. It does not cause an erection automatically, and it does not increase sex drive.
The 36-hour window: how long tadalafil lasts
30 min+
before sex for an as-needed dose
36 hrs
how long a single dose can keep working
Any time
with or without food
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 about 4 hours for sildenafil — which is why it is sometimes called “the weekend pill”. Take it at least 30 minutes before sex. Unlike sildenafil, it is not affected by food. Arousal is still needed for it to work, and it does not cause a continuous erection.
Tadalafil doses: as-needed or daily
Tadalafil comes as 2.5mg, 5mg, 10mg and 20mg tablets. There are two ways to take tadalafil for ED. The choice depends on how often you have sex and whether you prefer to plan or to be ready at any time.
| Approach | Dose | Best for |
|---|---|---|
| As needed | Usually 10mg, taken at least 30 minutes before sex. May be increased to 20mg. No more than one dose a day. | Men who have sex less often and prefer to take a tablet when needed |
| Daily | 5mg once a day at about the same time (sometimes 2.5mg) | Men who have sex twice a week or more, want spontaneity, or also have prostate symptoms |
| Enlarged prostate | 5mg once a day | Men with urinary symptoms of BPH, with or without ED |
On the daily dose, tadalafil builds up to a steady level in the body over about five days. If you have severe kidney problems or liver problems, the maximum as-needed dose is usually 10mg and the daily dose may not be suitable. Your prescriber will also check any other medicines you take (see below). For more on taking it every day, see our daily tadalafil guide.
How to take tadalafil
1
Swallow the tablet whole with water
It can be taken with or without food. Do not drink grapefruit juice while taking tadalafil, as it can raise the level of the medicine in your blood.
2
As needed: allow at least 30 minutes
There is no need to time it precisely, because the effect can last up to 36 hours.
3
Daily: take it at the same time each day
Choose a time you will remember. After about five days the level in your body is steady, so you do not need to plan sex around a tablet. If you miss a dose, take it when you remember, but never take two doses on the same day.
4
Keep alcohol low and never double up
Heavy drinking can make it harder to get an erection. Do not take more than one tablet in 24 hours, and do not combine tadalafil with other ED medicines.
5
Give it a fair trial
If it has not worked after several attempts at the right dose, speak to your prescriber about a dose change or a different medicine.
Tadalafil for an enlarged prostate (BPH)
Tadalafil 5mg once daily is licensed to treat the urinary symptoms of an enlarged prostate, a common condition in older men where the prostate presses on the urethra. Sildenafil is not licensed for this use. Tadalafil can ease:
- a weak or slow urine stream
- a sudden or frequent urge to pass urine
- getting up at night to pass urine
- a feeling of not fully emptying the bladder
Because the same 5mg daily dose treats both, one tablet can cover ED and prostate symptoms. Before starting tadalafil for urinary symptoms, you should be assessed by your GP or prescriber, which may include an examination or blood test, to rule out other causes such as prostate cancer.
Tadalafil side effects
Side effects are usually mild and short-lived.
| How often | Side effects |
|---|---|
| Common up to 1 in 10 men | Headache; flushing; blocked nose; indigestion; back pain; muscle aches; pain in the arms or legs |
| Uncommon or rare | Examples include dizziness, stomach pain, blurred vision, eye pain, palpitations, a fast heartbeat and nosebleeds |
Back pain and muscle aches are usually mild and pass on their own, and a pharmacist can recommend a suitable painkiller. Speak to your prescriber if any side effect continues or bothers you.
Get medical help straight away if you have an erection that is painful or lasts more than 2 hours (go to A&E straight away, and do not drive yourself), chest pain during or after sex (call 999 and tell them you have taken tadalafil), a sudden decrease or loss of vision or hearing (stop tadalafil and go to A&E straight away), or signs of a serious allergic reaction (call 999).
Who should not take tadalafil?
Never take tadalafil with nitrates. This includes GTN spray, tablets or patches, isosorbide mononitrate or dinitrate, nicorandil, and recreational “poppers” (amyl nitrite). Together they can cause a sudden, dangerous drop in blood pressure. Do not take it with riociguat either. Because tadalafil lasts so long, at least 48 hours should pass after a dose before a nitrate is given.
Do not take tadalafil if you
- take nitrates, nicorandil or riociguat, or use poppers
- are allergic to tadalafil or any of the other ingredients in the tablet
- have been advised that sexual activity is not safe for your heart
- have had a heart attack in the last 90 days or a stroke in the last 6 months
- have low blood pressure (below 90/50 mmHg), uncontrolled high blood pressure, or an uncontrolled heart rhythm problem
- have unstable angina or angina during sex, or have had heart failure in the last 6 months that limits ordinary physical activity, even mildly (NYHA class 2 or above)
- have ever lost sight in one eye because of reduced blood flow to the optic nerve (NAION)
Tell your prescriber first if you
- take an alpha-blocker (such as tamsulosin) or other blood pressure medicines — taking tadalafil with doxazosin is not recommended
- take a medicine that raises tadalafil levels, such as ritonavir, ketoconazole, itraconazole, clarithromycin or erythromycin
- take rifampicin or certain epilepsy medicines, which can make tadalafil work less well
- have kidney or liver problems
- have a physical deformity of the penis (such as Peyronie’s disease), or a condition that increases the risk of a prolonged erection, such as sickle cell disease, leukaemia or multiple myeloma
- have any eye condition or have ever had sudden loss of vision
For a full list of medicines, alcohol and recreational drugs that interact with tadalafil, see our guide to Cialis drug interactions.
How to get tadalafil in the UK
Most tadalafil is prescription-only in the UK. The exception is tadalafil 10mg sold as a pharmacy medicine (such as Cialis Together), which men aged 18 and over can buy from a pharmacy after speaking with a pharmacist. The 2.5mg, 5mg and 20mg strengths, daily use and treatment for an enlarged prostate all need a prescription.
| Route | What you get | How it works |
|---|---|---|
| NHS prescription | Generic tadalafil | From your GP after a health check, if it is suitable for you (rules may differ in Wales and Northern Ireland). NHS prescription charges apply in England unless you are exempt; prescriptions are free in Scotland, Wales and Northern Ireland. |
| Private prescription online | Generic tadalafil or branded Cialis | Through a GPhC-registered online pharmacy, such as Access Doctor, after an online consultation reviewed by a prescriber. |
| Pharmacy, without a prescription | Tadalafil 10mg (e.g. Cialis Together), as needed only | Men aged 18 and over, after a consultation with a pharmacist. Not for daily use. See a doctor within 6 months for a check-up, as erection problems can be linked to conditions such as heart disease or diabetes. |
Avoid unlicensed sellers. ED tablets sold through unregulated websites or social media may contain the wrong dose, no active ingredient or harmful contaminants. Only buy tadalafil from a GPhC-registered pharmacy. See why Kamagra and similar products are dangerous.
Tadalafil vs sildenafil
| Tadalafil (Cialis) | Sildenafil (Viagra) | |
|---|---|---|
| How long it lasts | Up to 36 hours | About 4 hours |
| Starts working | From about 30 minutes | From about 30 minutes (take about 1 hour before) |
| Effect of food | Not affected | A heavy meal can delay it |
| Daily option | Yes — 2.5mg or 5mg once a day | No — as needed only |
| Also treats an enlarged prostate | Yes (5mg daily) | No |
Neither is “stronger”: studies show they work about as well as each other. Tadalafil suits spontaneity and men who also have prostate symptoms; sildenafil suits planned, occasional use. See our sildenafil guide and full tadalafil vs sildenafil comparison. Tadalafil does not treat premature ejaculation; see our premature ejaculation treatment page.
UK safety and prescribing information
- Legal status: most tadalafil is a prescription-only medicine (POM) in the UK; tadalafil 10mg sold as a pharmacy (P) medicine, such as Cialis Together, can be bought by men aged 18 and over after speaking with a pharmacist. Access Doctor supplies MHRA-licensed UK medicines, dispensed by our GPhC-registered pharmacy (#9011198) only after a prescriber has assessed your consultation. It is illegal to sell or supply prescription-only medicines without a prescription in the UK.
- Maximum dose: no more than one tablet a day. The maximum as-needed dose is 20mg.
- Interactions: never take tadalafil with nitrates (including GTN spray), nicorandil, “poppers” or riociguat. Tell your prescriber about alpha-blockers, other blood pressure medicines, HIV medicines such as ritonavir, and antifungals or antibiotics such as ketoconazole or clarithromycin.
- Driving: tadalafil can cause dizziness. Check how it affects you before driving or using machinery.
- NHS: in England and Scotland, your GP can prescribe generic tadalafil for erection problems on the NHS if it is suitable for you. In England, the old restrictions that limited it to men with certain medical conditions were removed on 1 October 2025. Branded Cialis is still restricted on the NHS, and the rules may differ in Wales and Northern Ireland, so ask your GP. NHS prescription charges apply in England unless you are exempt; prescriptions are free in Scotland, Wales and Northern Ireland.
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Start your consultation →Frequently Asked Questions
Is tadalafil the same as Cialis?
Yes. Tadalafil is the active ingredient in Cialis. Generic tadalafil contains the same medicine at the same strengths and works in exactly the same way. The main differences are the name on the packet and the price, with generic tadalafil usually costing much less.
How long does tadalafil last?
A single dose of tadalafil can work for up to 36 hours, which is why it is sometimes called the weekend pill. This is much longer than sildenafil, which lasts about 4 hours. Take it at least 30 minutes before sex. Food does not affect it.
How long does tadalafil take to work?
Tadalafil can start to work from about 30 minutes, so take it at least 30 minutes before sex. You still need to be sexually aroused for it to work.
Does food affect tadalafil?
No. Tadalafil can be taken with or without food, and a meal does not change how well it is absorbed. This is a practical difference from sildenafil, which can take longer to work after a heavy meal. Do not drink grapefruit juice while taking tadalafil.
What is the usual starting dose of tadalafil?
For as-needed use, the usual starting dose is 10mg, taken at least 30 minutes before sex. Your prescriber may increase it to 20mg. For daily use, the usual dose is 5mg once a day, sometimes reduced to 2.5mg. Never take more than one tablet a day.
Can I take tadalafil every day?
Yes. Tadalafil is available as a low daily dose, usually 5mg once a day, as well as an as-needed dose. The daily option suits men who have sex often or want to be ready without planning, and the 5mg daily dose also treats the urinary symptoms of an enlarged prostate.
What are the most common side effects of tadalafil?
The most common side effects are headache, flushing, a blocked nose, indigestion, back pain and muscle aches. Back pain and muscle aches are usually mild and pass on their own. A pharmacist can recommend a suitable painkiller, and you should speak to your prescriber if they continue.
Does tadalafil work better than sildenafil?
Neither is better overall. Studies show they work about as well as each other. Tadalafil lasts up to 36 hours and has a daily option, so it suits spontaneity, while sildenafil lasts about 4 hours and suits planned, occasional use.
Can tadalafil help with an enlarged prostate?
Yes. Tadalafil 5mg once a day is licensed to treat the urinary symptoms of an enlarged prostate, such as a weak stream, urgency and needing to pass urine at night. It can treat these symptoms and erectile dysfunction at the same time.
Can I get tadalafil without a prescription in the UK?
Only in one form. Tadalafil 10mg sold as a pharmacy medicine, such as Cialis Together, can be bought by men aged 18 and over from a pharmacy after speaking with a pharmacist. All other tadalafil, including the 2.5mg, 5mg and 20mg strengths, daily use and treatment for an enlarged prostate, needs a prescription from your GP or a registered online pharmacy prescriber.
Can I get tadalafil on the NHS?
Often, yes. In England and Scotland, your GP can prescribe generic tadalafil for erection problems if it is suitable for you. In England, the old restrictions that limited it to men with certain medical conditions were removed on 1 October 2025. Branded Cialis is still restricted on the NHS, and the rules may differ in Wales and Northern Ireland, so ask your GP. You can also get tadalafil with a private prescription from a registered online pharmacy.
Can I drink alcohol with tadalafil?
A small amount of alcohol is unlikely to cause problems. Drinking too much can make it harder to get an erection and may make you feel dizzy, so keep alcohol low when you take tadalafil.
References
- NHS. Tadalafil (Cialis). nhs.uk
- NHS. Erectile dysfunction (impotence). nhs.uk
- National Institute for Health and Care Excellence. Clinical Knowledge Summaries: Erectile dysfunction. cks.nice.org.uk
- National Institute for Health and Care Excellence. British National Formulary: Tadalafil. bnf.nice.org.uk
- Electronic Medicines Compendium. Cialis and generic tadalafil film-coated tablets: Summaries of Product Characteristics. medicines.org.uk
- Medicines and Healthcare products Regulatory Agency. Yellow Card scheme: report a suspected side effect or a fake medicine. yellowcard.mhra.gov.uk
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Tadalafil is mainly a prescription-only medicine, and it needs a clinical or pharmacist assessment before it can be supplied. Always consult a qualified healthcare professional for diagnosis and treatment. In a medical emergency, call 999.
Reporting side effects: If you think a medicine has caused a side effect, you can report it to the MHRA through the Yellow Card scheme at yellowcard.mhra.gov.uk or the Yellow Card app. You can also report suspected fake or unlicensed medicines. Reporting helps keep medicines safe for everyone in the UK.