Short answer: Tadalafil (Cialis), taken when needed: take it at least 30 minutes before sex. It takes about 30 to 45 minutes to work, and its effect can last more than 24 hours. Those times are in line with the UK product information for Cialis (SmPC sections 4.2 and 5.1). Tadalafil is not affected by food. These tablets only work with sexual stimulation. Daily tadalafil, 2.5mg or 5mg, is not timed around sex: take one tablet a day, at about the same time each day.
This guide sets out what the UK product information for Cialis, generic tadalafil and Cialis Together, and the NHS, say as of October 2026: when to take each form of tadalafil, how long it lasts, whether 20mg lasts longer, daily tadalafil, food and alcohol, how often you can take it, and how long it stays in your body. We supply tadalafil taken when needed (10mg or 20mg) and daily tadalafil (2.5mg or 5mg) after a consultation reviewed by a GPhC-registered pharmacist, and Cialis Together after a pharmacist consultation, with no prescription needed.
How long does tadalafil take to work?
Tadalafil taken when needed takes about 30 to 45 minutes to work, and its effect can last more than 24 hours. Take it at least 30 minutes before sex. That is the instruction in the UK product information for Cialis and for generic tadalafil, for the 10mg and the 20mg tablet alike (SmPC section 4.2). Tadalafil is not affected by food.
These tablets only work with sexual stimulation. Tadalafil's product information explains why (SmPC section 5.1): when you are aroused, tadalafil helps the blood vessels in the penis relax so that blood can flow in, and without sexual stimulation it has no effect. Taking a tablet and waiting is not enough on its own. Try a tablet 4 to 8 times before deciding it does not work, then tell us.
The three forms of tadalafil we supply are taken in different ways:
| Form | When to take it | How often |
|---|---|---|
| Tadalafil, taken when needed (10mg or 20mg) | Take it at least 30 minutes before sex. | Take one tablet no more than twice a week, and never more than once in 24 hours. |
| Tadalafil, daily (2.5mg or 5mg) | Take one tablet a day, at about the same time each day. You take it whether or not you plan to have sex that day. | Every day. |
| Cialis Together (10mg), a pharmacy medicine | One 10mg tablet, at least 30 minutes before sex. | Maximum one tablet a day. If you take it at least twice a week, see your GP or start our full consultation to ask about a daily treatment. |
As of October 2026: for prescription tadalafil, from the UK product information for Cialis (SmPC section 4.2) and our consultation's limits; for Cialis Together, from its leaflet (section 3), its product information (section 4.2) and our pharmacy checklist. How long each one lasts is below.
How long does tadalafil last?
Tadalafil's effect can last more than 24 hours. That is for one tablet of tadalafil taken when needed, 10mg or 20mg. The UK product information for Cialis describes at-home trials in which the effect on erections lasted beyond 24 hours after a dose (SmPC section 5.1).
It does not keep you erect for that time. During it, the tablet helps when you are sexually aroused, and not otherwise. An erection that will not go down is a different matter: seek emergency treatment for an erection lasting longer than 4 hours. This is a medical emergency.
- TadalafilWorks in 30 to 45 min, lasts more than 24 hrs
- Tadalafil DailyOne tablet a day, at about the same time each day
Sildenafil (Viagra) is short acting: see how long sildenafil lasts. For how all four erectile dysfunction tablets differ, see sildenafil vs tadalafil.
How long does tadalafil 20mg last?
Tadalafil 20mg has the same timing as 10mg in the UK product information: taken when needed, its effect can last more than 24 hours, and the product information does not say that 20mg lasts longer (Cialis SmPC, sections 4.2 and 5.1). Either tablet may be taken at least 30 minutes before sex.
The usual starting dose is 10mg. The product information says 20mg might be tried if 10mg does not work well enough, and that the most common side effects (headache, indigestion, back pain and muscle aches) become more frequent as the dose goes up (sections 4.2 and 4.8). When you reorder, we ask how your last tablets worked and whether you had any side effects. If your dose did not work well enough and caused no side effects, the pharmacist can consider the next strength up. For every strength, and who can have which, see tadalafil dosage.
How long does daily tadalafil (Cialis 5mg) take to work?
Neither the UK product information nor the NHS gives a set time for daily tadalafil to start working. It is not timed around sex: take one tablet a day, at about the same time each day. You take it whether or not you plan to have sex that day.
The usual daily dose is 5mg, which can be lowered to 2.5mg if you do not tolerate 5mg well (Cialis 5mg SmPC, section 4.2). It is for men who expect to have sex at least twice a week. The available data does not suggest that taking it every day works better than taking tadalafil when needed.
Morning or evening makes no clinically relevant difference to how it is absorbed (SmPC section 5.2), so choose a time of day you will remember. If you forget a dose, the NHS advises taking it as soon as you remember, unless it is nearly time for the next one, in which case skip the missed dose. Never take two doses to make up for a forgotten one, or more than one tablet a day.
The product information does not give a time for how long one daily tablet lasts on its own: daily tadalafil is taken every day, and the timings for a single tablet are for tadalafil taken when needed (Cialis 5mg SmPC, section 5.1). If you are not sure daily tadalafil is helping, tell us when you reorder.
- How much we supply: 28 tablets on a first supply, up to 56 on later supplies.
- Not offered if: you have any liver or kidney disease, or you take doxazosin.
- Blood pressure medicines: if you take them, tadalafil can lower your blood pressure further. If you feel dizzy or sick, see your GP to review your blood pressure medicine.
- GP notification. Daily tadalafil should be added to your regular medication record. We will contact your GP with your consent, or you can tell them yourself. Will you tell my GP?
More on our daily tadalafil page.
What is Cialis, and how does it work?
Cialis is Eli Lilly's brand of tadalafil, licensed in the UK to treat erectile dysfunction in adult men (SmPC section 4.1). Like sildenafil (Viagra), tadalafil is a PDE5 inhibitor: when you are sexually aroused, it slows the breakdown of a chemical signal, cGMP, that relaxes the blood vessels in the penis, so blood flows in and an erection follows (section 5.1). For each step in more detail, see how Viagra works: tadalafil works the same way.
Generic tadalafil tablets contain the same active ingredient at the same strength and are licensed in the UK. We supply tadalafil for erectile dysfunction only. If you have urinary symptoms, please see your GP.
Does food or alcohol change how quickly tadalafil works?
Food does not change how quickly tadalafil works, but drinking too much alcohol can make an erection harder to get. A heavy or high-fat meal can delay how quickly sildenafil, vardenafil and avanafil work. Tadalafil is not affected by food. The Cialis product information says a meal changes neither how quickly nor how much of it your body absorbs (SmPC section 5.2).
The NHS says drinking alcohol while taking tadalafil can increase your risk of low blood pressure, which can make you feel dizzy or light-headed, and advises avoiding drinking too much, as this can make getting an erection more difficult. Drinking less alcohol can help your erections. More in Viagra, Cialis and alcohol.
Tadalafil: avoid grapefruit juice. Grapefruit juice is expected to raise the amount of tadalafil in your blood, which can make side effects more likely (SmPC section 4.5).
How often can you take tadalafil?
Tadalafil taken when needed: take one tablet no more than twice a week, and never more than once in 24 hours.
The product information's limit is once a day, and it says the 10mg and 20mg tablets are for taking before sex, not every day (Cialis SmPC, section 4.2). If you expect to need treatment more than twice a week, the consultation shows you daily tadalafil first, and tadalafil taken when needed is not offered. There is also a limit on how much we can supply: maximum 8 tablets per 4 weeks.
Daily tadalafil: take one tablet a day, at about the same time each day. Cialis Together: maximum one tablet a day, and it is not for frequent use (more below). For each strength and the most you can take, see tadalafil dosage.
Answer a few questions about your health and the medicines you take. A GPhC-registered pharmacist reviews every consultation, and if they cannot approve your order, we refund you in full.
Start your consultationHow long does tadalafil stay in your system?
Tadalafil's effect can last more than 24 hours. Tadalafil's product information says that at least 48 hours should pass after the last dose of tadalafil before a nitrate is considered, even in an emergency.
That 48 hours comes from a study in the product information: in 150 people taking tadalafil 20mg a day for 7 days, tadalafil's added effect on the fall in blood pressure caused by a nitrate (glyceryl trinitrate under the tongue) lasted more than 24 hours, and could no longer be detected 48 hours after the last dose. The rule covers every strength from 2.5mg to 20mg, daily or when needed (Cialis SmPC, section 4.5). If you ever need emergency treatment for chest pain, tell the doctor or paramedic that you take tadalafil and when you last took it.
Your body breaks tadalafil down, mainly through an enzyme called CYP3A4, and clears it mostly in the faeces and partly in the urine (SmPC section 5.2). Some medicines, and grapefruit juice, slow that breakdown and raise the amount of tadalafil in your blood; others, such as rifampicin, speed it up and can make tadalafil work less well (section 4.5). We do not supply tadalafil to anyone taking:
- An HIV protease inhibitor (atazanavir, darunavir, ritonavir, fosamprenavir, lopinavir, saquinavir or tipranavir)
- Ketoconazole, itraconazole, voriconazole or clarithromycin
- Rifampicin, phenobarbital, phenytoin, carbamazepine or St John's Wort
The consultation asks about every other medicine you take too.
Tadalafil clears more slowly in men aged 65 and over and in men with kidney problems (section 5.2). The product information says no dose change is needed for age, but sets a lower maximum dose with severe kidney problems (section 4.2). We do not supply tadalafil with severe kidney failure, eGFR under 30, or dialysis, and daily tadalafil is not offered with any kidney problem.
Can you flush tadalafil out of your system?
No. There is no way to clear tadalafil from your body faster: even dialysis removes a negligible amount of it (Cialis SmPC, section 4.9). What to do depends on why you are asking:
- Prolonged erection. Seek emergency treatment for an erection lasting longer than 4 hours. This is a medical emergency.
- Cardiovascular symptoms. Stop and call 999 if you get chest pain, dizziness or fainting during or after sexual activity. Do not take another dose.
- You took more than your dose. The NHS says taking an extra dose of tadalafil can be dangerous, and to get help from NHS 111 if you have taken more than your prescribed dose.
- A side effect such as a headache or back pain. The product information describes the side effects reported with it as transient and generally mild or moderate (section 4.8). Tell us if one bothers you or does not go away. Less common side effects are listed in the leaflet in your pack. Please read it before your first dose. More in tadalafil side effects.
Does Cialis make you last longer?
Cialis is not licensed to make you last longer: tadalafil is licensed in the UK to treat erectile dysfunction in adult men (SmPC section 4.1), not premature ejaculation, which the NHS describes as ejaculating sooner than you or your partner would like. It helps you get and keep an erection when you are sexually aroused (section 5.1). If you mean how long the tablet itself works, its effect can last more than 24 hours.
If coming too soon keeps happening and is a problem for you, the NHS advises seeing your GP, who can talk it through and may refer you to a specialist. Not sure what counts as erectile dysfunction? See what is erectile dysfunction.
How long does Cialis Together last?
With Cialis Together, when you are sexually stimulated, you can get an erection from 30 minutes and for up to 36 hours after one tablet. That is the timing its leaflet gives (section 3). Cialis Together contains tadalafil 10mg, the same active ingredient as prescription Cialis. The MHRA reclassified it as a pharmacy medicine on 14 March 2023, with a maximum of one tablet a day and packs of up to 8 tablets. We supply it after a pharmacist consultation, to men aged 18 to 64, with our pharmacy checklist asked before every order.
- One 10mg tablet, at least 30 minutes before sex.
- Maximum one tablet a day.
- Not for continuous daily use. Talk to your doctor if you feel you need it every day.
If you find you take it at least twice a week: Cialis Together is not for frequent use. Please see your GP, or start our full consultation to ask about a daily treatment.
Erection problems can be an early sign of heart disease, diabetes or high blood pressure. Please book a check-up with your GP as soon as you can, within 6 months of starting Cialis Together. Read the leaflet in your pack carefully before you take it.
See all our erectile dysfunction treatments.