The Independent Pharmacy

What Is Tadalafil and How Does It Work?

Andy Boysan
Andy BoysanBPharmDirector & Superintendent Pharmacist

Reviewed on 23 Jan 2023

If you’ve heard about Tadalafil but you’re looking for some deeper information about it, you’re in the right place.

We created this page to answer the most common questions about Tadalafil. We’ll run through everything you need to know from how it’s used to the precautions a Tadalafil user needs to follow before taking. Let’s get started.

What Tadalafil is and what it’s used for

Tadalafil is a medical treatment prescribed for erectile dysfunction (when someone isn’t able to achieve or maintain a strong erection). Tadalafil tablets are the unbranded, generic version of the well-known Erectile Dysfunction (ED) medication Cialis (tadalafil is also the active ingredient in Cialis).

Cialis Tablets (10mg & 20mg)
Cialis Tablets (10mg & 20mg)
View Treatment

Tadalafil results in a harder and longer-lasting erection, but it will not produce an erection without you being sexually stimulated or ‘turned on’.

Suffering from erectile dysfunction affects not only someone’s ability to enjoy a healthy sex life but also their self-confidence and feelings of self-worth. Because of this, treating erectile dysfunction isn’t a trivial matter. If you’re having difficulties in this area, you deserve support.

How Tadalafil works

Tadalafil works by increasing blood flow to the penis helping the spongy tissue of the penis fill up with blood, making it become harder.

In the human body, there’s a substance known as cGMP that relaxes smooth muscle tissues. When it affects the walls of blood vessels, those vessels dilate, allowing them to carry more blood and thus improving blood flow — the better the rate of blood flow to the penis, the stronger the erection.

However, an enzyme known as PDE5 can cause problems. When it encounters cGMP, it binds to it and breaks it down, rendering it ineffective. And while the root cause of erectile dysfunction can vary, blocking PDE5 always seems to be an effective treatment.

Tadalafil is a PDE5 inhibitor. When consumed, it stops PDE5 from breaking down cGMP as quickly or effectively. This allows the cGMP to have a much greater impact on blood flow, especially to the penis, majorly improving the user’s ability to achieve and maintain an erection.

How long Tadalafil lasts

How long Tadalafil lasts

While the strength of the effect will depend on the dosage, the duration will typically cap out at around 36 hours. In very rare cases it might last slightly longer, but in many more instances, you might only get 24 hours from a particular dose. You’ll need to try it to see how it affects you.

This does not mean that you will have an erection for 36 hours, but you should have the ability to achieve a satisfactory erection during the 36-hour period. You will still require sexual stimulation to gain an erection and your erection should go after ejaculation.

This places it in stark opposition to a treatment such as Viagra (sildenafil), which in comparison only lasts up to four hours on average. For more information on what it’s like to use Tadalafil, and how it compares to other treatments, visit our Tadalafil reviews page.

How and when to take Tadalafil

Tadalafil is an oral medication provided in tablets of 10mg and 20mg. Most men start off with 10mg tablets and find these effective. However, if you find that the 10mg tablets do not have the desired effect after trying around eight times, you can increase the strength to 20mg tablets.

Tadalafil tablets take at least 30 minutes to take effect so ideally, you need to take them around 60 minutes before you want to achieve an erection.

You shouldn’t take more than one tablet of Tadalafil in a 36-hour period, regardless of the strength of tablet you take.

If you take too much, it can greatly worsen the side effects of Tadalafil, causing intense chest pain, nausea, dizziness, and various other unpleasant symptoms.

Take a look at our dedicated Tadalafil side effects page if you have further questions.

What precautions are important for Tadalafil

Before (and during) using Tadalafil to treat your erectile dysfunction, read through the following precautions, and be sure to follow them carefully:

  • Inform your regular doctor that you’re using Tadalafil. Should you suffer any side effects, or in an unlikely case, a medical emergency and be unable to communicate, your treatment history will be essential information.
  • Fully disclose any relevant medical conditions, namely those relating to your heart. Because increased blood flow and the physical stresses of sexual activity will tax your heart, it’s vitally important that any existing conditions be known and addressed beforehand.
  • Confirm that any other medicines you’re using will not present any conflicts. Medicines to avoid using alongside Tadalafil include those used to combat heart conditions (most notably nitrate medications). Additionally, do not mix Tadalafil with other erectile dysfunction treatments. This will be checked during your consultation.
  • Cut back on alcohol before (and while) using Tadalafil. Drinking too much can lead to issues (such as low blood pressure or an elevated heart rate) that will interfere with the effects of Tadalafil and will potentially cause side effects.

In general, Tadalafil is a very safe and reliable treatment and doesn’t require you to make sweeping changes to your daily routine. Just be aware of these basic precautions, inform your doctor of all your medical history, and ensure you follow all the instructions with the medicine.

Generic versus branded names

The difference between cialis and tadalafil

Tadalafil is the generic non-branded name for the popular drug Cialis (also known as Adcirca when prescribed to treat high blood pressure). It is named because tadalafil is the active ingredient in Cialis. When the patent on Cialis expired, it became possible for other pharmaceutical manufacturers to produce the same treatment but at a lower cost.

Click here to find out more about what Cialis is.

Why you need a prescription for Tadalafil

Tadalafil may be very safe overall, but it isn’t suitable for everyone — most notably, those with histories of heart conditions. If your heart has suffered significant damage, the stresses of using Tadalafil would likely cause major issues. This is why it isn’t available as an over-the-counter option.

Fortunately, to be prescribed Tadalafil online, it won’t take very long to get through the consultation process and confirm that you’re eligible to use Tadalafil. All you need to do is tell us about your relevant medical history and any other medications you’re taking, and we can establish whether this drug is appropriate. If it is, you can go ahead and buy Tadalafil online directly from us.

For over the counter alternatives, take a look at Viagra Connect.

Is Tadalafil available through the NHS?

Not always. Erectile dysfunction treatment is only available through the NHS if you meet very specific criteria. This limits assistance to those who have major life-altering conditions such as diabetes, Parkinson’s disease, prostate cancer, or Huntington’s disease.

And even if you meet the criteria, you may have little choice in the type of treatment you receive — most commonly, a patient will be offered sildenafil, the generic version of Viagra, as the first treatment option. If that isn’t available, then someone might be prescribed Cialis, but it’s uncommon, and any prescribed amount will be limited.


Tadalafil is the non-branded version of Cialis, a popular oral treatment for erectile dysfunction. It improves blood flow to produce a stronger and more reliable erection and that can be achieved for up to 36 hours after taking. It isn't recommended for someone with a history of heart problems, so it's only available upon prescription. If you think it may be right for you, review this page and contact us for a free consultation.


Need something else?

We stock 1044 treatments for 90 conditions

Or browse all treatments or conditions

A customer at the pharmacist looking for medication