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Active ingredient

Tadalafil (generic Cialis)

What is tadalafil?

Tadalafil is the active substance of Cialis and a prescription-only medicine in the EU/EEA. It treats erectile dysfunction in adult men and, as 5 mg once daily, the urinary symptoms of an enlarged prostate (BPH). Its EU product information reports improved erections up to 36 hours after an on-demand dose, at most 20 mg once a day.

Reviewed by the Kam4eu editorial team on 13 August 2026 · Next review August 2027

Tadalafil medicines we deliver

Browse the full Erectile Dysfunction range

8 generic Tadalafil products — same molecule, different brands, formats and pack sizes.

What tadalafil is used for

  • Erectile dysfunction in adult men; sexual stimulation is required for it to work.
  • Signs and symptoms of benign prostatic hyperplasia (an enlarged prostate) in adult men, as 5 mg once daily.
  • Not indicated for women or for anyone under 18.

Source: EMA — Cialis (tadalafil) product information (EU SmPC)

How tadalafil differs from the alternatives

  • Response window per the EU product information: improved erectile function up to 36 hours after a tadalafil dose; studies of sildenafil and vardenafil showed responses 4 to 5 hours after a dose.
  • The only one with a once-daily option for ED: 5 mg (reducible to 2.5 mg) at about the same time each day, for men expecting sex at least twice a week, reassessed periodically.
  • Absorption is not affected by food, whereas a meal may delay the onset of sildenafil, vardenafil and avanafil.
  • Tadalafil 40 mg once daily is an EU dose only for pulmonary arterial hypertension (Adcirca, taken as two 20 mg tablets) — a different medicine and condition from Cialis for ED.

Sildenafil vs tadalafil vs vardenafil: see the side-by-side comparison in our erectile dysfunction guide

Sildenafil vs tadalafil vs vardenafil vs avanafil

The four PDE5 inhibitors used for erectile dysfunction, compared on what each one's EU product information (Summary of Product Characteristics) states for adult men. All four are prescription-only medicines in the EU/EEA — your doctor chooses the medicine and dose.

PDE5 inhibitor comparison from the EU product information
MedicineWhen to takeResponse windowEU maximum doseFoodSource
SildenafilOriginator: ViagraAbout 1 hour before sexual activityErections still produced 4–5 hours after the dose (clinical study)100 mg, at most once a dayTaking it with food may delay the onset of effectViagra SmPC (EMA)
TadalafilOriginator: CialisAt least 30 minutes before sexual activityImproved erectile function up to 36 hours after the dose20 mg on demand, at most once a dayAbsorption not affected by food — with or without a mealCialis SmPC (EMA)
VardenafilOriginator: LevitraAbout 25 to 60 minutes before sexual activityBetter success than placebo when sex was attempted 4–5 hours after the dose20 mg, at most once a dayWith or without food; a high-fat meal may delay the onsetLevitra SmPC (EMA)
AvanafilOriginator: SpedraAbout 15 to 30 minutes before sexual activityNot stated in the EU product information200 mg, at most once a dayTaking it with food may delay the onset of effectSpedra SmPC (EMA)

Safety essentials

  • Never with any organic nitrate or with riociguat — risk of a dangerous fall in blood pressure.
  • Not for men with a heart attack in the last 90 days, unstable angina or angina during sex, heart failure (NYHA class 2 or worse) in the last 6 months, uncontrolled arrhythmias, blood pressure below 90/50 mmHg, uncontrolled high blood pressure, or a stroke in the last 6 months.
  • Not after loss of vision in one eye from NAION; sudden visual problems mean stop and see a doctor immediately.
  • An erection lasting 4 hours or more needs immediate medical help — untreated priapism can cause permanent damage. In an emergency call 112.

Source: EMA — Cialis (tadalafil) product information (EU SmPC)

Interactions

  • Potent CYP3A4 inhibitors (ritonavir, saquinavir, ketoconazole, itraconazole, erythromycin): use with caution — ketoconazole raised tadalafil exposure up to 4-fold.
  • Clarithromycin and grapefruit juice are also expected to raise tadalafil levels.
  • Alpha-blockers can cause symptomatic low blood pressure; the combination of tadalafil and doxazosin is not recommended.
  • Blood-pressure medicines: tadalafil may lower blood pressure further; a dose adjustment may be considered when daily treatment starts.
  • Rifampicin and other CYP3A4 inducers: rifampicin cut tadalafil exposure by 88%, which can be expected to reduce its effect.
  • Other PDE5 inhibitors or ED treatments: combinations have not been studied — do not take them together.

Source: EMA — Cialis (tadalafil) product information (EU SmPC)

How it works

Tadalafil blocks the PDE5 enzyme, allowing cyclic guanosine monophosphate (cGMP) to build up and the blood vessels in the penis to relax, which improves blood flow during sexual stimulation. As with other PDE5 inhibitors, sexual arousal is required for it to work. The EU product information for Cialis says to take it at least 30 minutes before sexual activity, and reports improved erectile function up to 36 hours after a dose.

How it is taken

Tadalafil is taken by mouth, either before anticipated sexual activity or, in some cases, as a low daily dose, at the dose advised by your doctor. It can be taken with or without food, and unlike some similar medicines its effect is not strongly influenced by meals. Because of its long duration of action, no more than one dose should be taken in any 24-hour period. Always follow the patient information leaflet and the advice of your doctor or pharmacist.

Tadalafil side effects

The EU product information names headache, indigestion (dyspepsia), back pain and muscle aches (myalgia) as the most commonly reported side effects, becoming more frequent at higher doses; they were transient and generally mild or moderate. With once-daily dosing, most headaches occur within the first 10 to 30 days.

Source: EMA — Cialis (tadalafil) product information (EU SmPC)

Common (usually mild and temporary):

  • Headache
  • Flushing
  • Indigestion
  • Back pain
  • Muscle aches
  • Nasal congestion

Stop and seek medical help if you experience:

  • A painful erection lasting longer than 4 hours (priapism) — seek urgent medical help
  • Sudden loss or decrease in vision in one or both eyes
  • Sudden loss or reduction in hearing, sometimes with ringing in the ears
  • Chest pain during or after sexual activity
  • Signs of a serious allergic reaction such as swelling of the face, lips or throat, rash or difficulty breathing

Safety & who should not take it

  • Must NOT be taken with nitrate medicines for angina or with nitric-oxide donors such as 'poppers', because of the risk of a serious fall in blood pressure.
  • Use with caution if you have heart or blood-vessel disease, or if your doctor has advised against sexual activity.
  • Tell your doctor about any liver or kidney problems, as the dose may need to be adjusted.
  • Caution is needed with low blood pressure and with alpha-blockers or other blood-pressure-lowering medicines.
  • Alcohol can add to a lowering of blood pressure and may cause dizziness.
  • Grapefruit and grapefruit juice may affect how the medicine works and are best avoided.
  • Not intended for use by women, children or anyone under 18 years of age.

Storage

Store in the original packaging at room temperature, out of the sight and reach of children, and do not use after the expiry date.

Frequently asked questions

Is there a tadalafil 40 mg?+

Not for erectile dysfunction in the EU. The Cialis product information caps the on-demand dose at 20 mg, at most once a day. In the EU, 40 mg once daily is the dose of tadalafil for pulmonary arterial hypertension (Adcirca, two 20 mg tablets), where treatment is started and monitored by a specialist. Tablets of 40 mg or more sold for ED exceed the EU maximum, so only a doctor should decide whether they are appropriate.

What is tadalafil 5 mg used for?+

Daily treatment. The EU product information allows 5 mg once a day, at about the same time each day, for men with ED who expect to have sex at least twice a week (reducible to 2.5 mg), and 5 mg once daily for the urinary symptoms of an enlarged prostate (BPH), with or without ED. Whether daily use is still appropriate should be reassessed periodically.

What are the side effects of tadalafil?+

The EU product information lists headache, indigestion, back pain and muscle aches as the most commonly reported, rising with the dose; they are usually transient and mild or moderate. Get medical help at once for chest pain, sudden loss of vision or hearing, or an erection lasting 4 hours or more — in an emergency call 112.

How long does tadalafil work for?+

The EU product information for Cialis reports improved erectile function up to 36 hours after a dose and says to take it at least 30 minutes before sexual activity. That is not a 36-hour erection: sexual stimulation is still needed, and no more than one dose should be taken a day.

Does food affect tadalafil?+

Its effect is generally not strongly affected by food, so it can be taken with or without a meal. Your doctor or pharmacist can give tailored advice.

How is tadalafil different from Cialis?+

Tadalafil is the active ingredient and the generic equivalent of the branded medicine Cialis; both contain the same active substance and work in the same way.

Important: This information is general and not a substitute for medical advice. Always read the patient information leaflet supplied with your medicine and consult a doctor or pharmacist before use — especially if you have existing health conditions or take other medication.

Sources

Tadalafil health guides

Why generic sildenafil and Cialis have 20 brand names

Summary: Kamagra, Cenforce, Fildena, Sildamax, Suhagra and Silagra are all sildenafil; Vidalista, Tadalista and Tadaga are all tadalafil. The molecule is identical and off-patent, so the brand name only tells you which manufacturer made it and in what format. Prices differ because of packaging, pack size and supply, not because one brand is stronger.

Read guide

Vidalista 20: how long does it last? The 36-hour window explained

Summary: Vidalista 20 (tadalafil 20mg) can work for up to 36 hours, the window the EMA product information for Cialis reports. That is why tadalafil is nicknamed the weekend pill. It doesn't mean a 36-hour erection: it means a day and a half in which arousal works normally. Heavy drinking can blunt it, and nitrates are never safe with it.

Read guide

Which medicine is best for sex? A decision guide

Summary: The best medicine for sex depends on the problem: sildenafil or tadalafil for erection problems, and dapoxetine for finishing too early. Per EMA product information, sildenafil still works 4–5 hours after a dose and tadalafil for up to 36 hours. All three are prescription-only in the EU/EEA, so ask a doctor which suits you.

Read guide

Cialis for men: is tadalafil better than Viagra?

Summary: Tadalafil (Cialis) is not stronger than sildenafil (Viagra) but lasts longer: up to 36 hours versus 4–5 hours, per EMA product information. Tadalafil suits spontaneity and can be taken with or without food; sildenafil suits planned occasions. Both are limited to one dose a day and are prescription-only in the EU/EEA.

Read guide

Related conditions & treatments

Conditions Tadalafil treats

Erectile Dysfunction

Other treatments for the same conditions

SildenafilVardenafilAvanafil

See also

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