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Active ingredient

Tadalafil

Tadalafil is the active ingredient in medicines used to treat erectile dysfunction in adult men, and in some cases the symptoms of benign prostatic hyperplasia (an enlarged prostate). It belongs to a class of medicines called phosphodiesterase type 5 (PDE5) inhibitors. It is the generic equivalent of the originally branded medicine Cialis. It helps men who have difficulty getting or keeping an erection suitable for sexual activity.

Reviewed by the Kam4eu Pharmacy 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.

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. A notable feature of tadalafil is its long duration of action, which can extend up to around 36 hours and has led to it sometimes being referred to as the 'weekend' treatment. It generally takes effect within roughly half an hour to an hour.

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.

Side effects

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

Why is tadalafil sometimes called the 'weekend' treatment?+

Its effect can last for up to around 36 hours, which is longer than several other erectile-dysfunction medicines, allowing more flexibility over timing. The leaflet provides further detail on duration.

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.

Tadalafil health guides

Tadalafil for Men: The 'Weekend' ED Option Explained

Summary: Tadalafil, the active ingredient behind the branded tablet Cialis, is a PDE5 inhibitor that can remain effective for up to 36 hours — considerably longer than shorter-acting alternatives like sildenafil — giving some men more flexibility around timing. This guide explains how it works, how it differs from sildenafil, the nitrate interaction that must always be avoided, and why suitability should be confirmed by a clinician rather than chosen independently.

Read guide

Cialis for Men: What Tadalafil Does and Who It Suits

Summary: Tadalafil is the active ingredient behind Cialis, a PDE5 inhibitor valued for its comparatively long duration of action, which allows either on-demand or daily dosing patterns depending on lifestyle and medical advice. This guide explains how it works, who tends to find it suitable, and the safety considerations — including the nitrate interaction — that make professional guidance essential. Kam4eu supplies generic tadalafil, chemically identical to the branded product, across the UK and EU/EEA.

Read guide

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; the brand name only tells you which manufacturer made it and in what format. Here's how to read a generic name, why the prices differ anyway, and which differences actually matter.

Read guide

How long does tadalafil last? The 36-hour window explained

Summary: Tadalafil lasts up to 36 hours — a half-life of 17.5 hours gives it the longest window of any ED medicine, covering a whole weekend from one Friday dose. Onset is 30–45 minutes, food barely matters, and the dose changes intensity, not duration. Here's the hour-by-hour reality, the overlap rule for redosing, and when the long window is the wrong choice.

Read guide

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