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What is Tadalafil (Cialis)?

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Tadalafil, also known as Cialis, is a medication used to treat erectile dysfunction and the symptoms of benign prostatic hyperplasia (enlarged prostate). Tadalafil is the non-branded (generic) version of Cialis, and is one of the newer drugs used to treat impotence. It does not help to increase libido, and will only work when you are sexually stimulated.

 

How Does Tadalafil Work?

Tadalafil belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors. It helps to achieve and keep an erection that is hard enough for sex. When you are sexually stimulated, nitric oxide is released in the penis. This produces a chemical messenger called cGMP, which relaxes the smooth muscle and increases blood flow to the penis causing an erection. cGMP must be present in order to achieve an erection. The breakdown of cGMP is what causes erectile dysfunction. Tadalafil prevents the breakdown of cGMP, so that blood can enter into the penis, causing an erection. 

If there is no sexual excitement, tadalafil will not work. This is because cGMP is required to achieve an erection, and tadalafil works by stopping the breakdown of cGMP. Where there is no sexual stimulation, there is no cGMP, and tadalafil will be unable to exert its effect. 

What Is the Usual Dose of Tadalafil?

Tadalafil is available in four different strengths, which are 2.5mg, 5mg, 10mg and 20mg. The usual dosage is 10 mg when you need it. Take the tablet with water or juice (but not grapefruit juice). [1]

The lower strengths of 2.5mg and 5mg should be taken every day and have a continuous effect. They are recommended for individuals who have more than 2 sexual encounters per week. The 10mg and 20mg strengths should be taken around half an hour before sex.

How Long Does Tadalafil Last?

The lower strengths (2.5mg and 5mg) of tadalafil have a continuous effect, whereas the higher strengths, tadalafil 10mg and 20mg, can last for up to 36 hours. This does not mean that you will have a continuous erection every day, or for 36 hours. If you are taking the lower strength tablets every day, they will work only where there is sexual stimulation, without the need to take a tablet before sexual activity. The higher strength tablets will work for up to 36 hours, only when there is sexual excitement. 

When Should I Take Tadalafil?

If you have been prescribed a lower strength (2.5mg or 5mg), you should take tadalafil every day. The higher strengths (5mg or 10mg) should be taken around 30 minutes before sex. You should only take one tablet a day. If you miss a dose, take it as soon as possible. However, if it's almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

If you have not experienced the desired results, you should not take another tablet until the following day. It can take a while before your body gets used to any type of erectile dysfunction medicine. It is recommended to try treatment on a few separate occasions, to allow your body to adjust. If this hasn’t worked, you should speak to your doctor about increasing the dose, or trying a new erectile dysfunction treatment.

Is Tadalafil Safe to Take?

Tadalafil is generally considered to be a safe treatment for ED, however, as with all medication, there may be individuals for whom tadalafil is not suitable. If you have certain medical conditions such as very high or low blood pressure, kidney or liver failure, stomach ulcers, bleeding disorders or severe heart problems, you should speak to your doctor. 

Tadalafil can also interact with certain medicines such as alpha blockers, some heart medication, epilepsy drugs, certain antibiotics, nitrates, antivirals, some antifungals and cancer treatments. You should speak to your doctor about taking tadalafil if you have a medical condition, or if you are taking medication. You may still be eligible to use tadalafil, but your doctor may wish to monitor you. You should always read the Patient Information Leaflet provided with your medication, and raise any concerns with a healthcare professional.

Does Tadalafil Work?

According to clinical trials and reviews online, tadalafil does work and has an extremely high success rate. It has a proven track record, which makes it one of the most popular ED treatments currently available. However, it is important to note that everyone is different, and tadalafil may not always have the same effect on individuals. If tadalafil hasn’t worked for you, you should ask your doctor or pharmacist about trying a different type of treatment.

What Are the Side Effects of Tadalafil?

Side effects may include nausea, facial flushing (where your face suddenly feels hot) and nasal congestion. These do not affect everyone, and are temporary. If you experience serious side effects including chest pain, a seizure, loss of hearing or vision, a painful erection or an erection that lasts for longer than 4 hours, stop taking the medicine and seek medical attention. You can also report side effects through the Yellow Card safety scheme. [2]

What Is the Difference Between Tadalafil and Viagra (Sildenafil)?

Tadalafil and Viagra (sildenafil) have a few differences, the main one being the duration of action. Tadalafil lasts much longer, and is active for up to 36 hours, whereas Viagra lasts for up to 6 hours. Tadalafil also works quicker than sildenafil, and only needs to be taken 30 minutes before sex. It is recommended to take Viagra 1 hour before sexual activity. Tadalafil is also available as a daily dose, which allows for spontaneous sexual activity. Viagra does not offer this option and is only available to take before sex. To explore this in greater detail, see our sildenafil v tadalafil article.

What Should I Do If Tadalafil isn’t Working for Me?

If tadalafil does not work the first time, you should give it several attempts before trying an alternative. This is because it can take time for your body to adjust to it. If the dose you have been prescribed hasn’t worked after a few attempts, you should speak to your doctor or pharmacist. The dose may be increased to a higher strength. If you are already taking the higher strength, you may be prescribed an alternative.

What Are the Alternatives to Tadalafil?

  • Sildenafil – Also available as Viagra. Needs to be taken 1 hour before sexual activity, and can last up to 6 hours. This is the most popular treatment for ED, and is also the most affordable.
  • Vardenafil – Also known by its branded name, Levitra. Needs to be taken 1 hour before sexual activity, and can last up to 6 hours. This treatment is recommended for diabetics.
  • Spedra – This ED treatment can take effect within 15 minutes, and lasts for up to 5 hours.

How Can I Get Tadalafil?

If you wish to obtain tadalafil, you should see your GP. You may be entitled to tadalafil on the NHS, although this is usually limited to a supply of 4 tablets per month (this can vary depending on the area you are based in). You may also wish to make an appointment with a private doctor, who will be able to prescribe you with tadalafil medicine. You will need to pay for the consultation fee, as well as the private prescription fee, which can vary depending on the pharmacy you choose to visit. 

You are also able to buy tadalafil online, after you have had a medical consultation. You should check that the pharmacy you are ordering from has the valid credentials, and is registered with the MHRA (Medicines and Healthcare Regulatory Authority) and the GPhC (General Pharmaceutical Council). 

Sources

  1. NHS (2022). How and when to take tadalafil. Retrieved on 3rd March 2025, from: https://www.nhs.uk/medicines/tadalafil/how-and-when-to-take-tadalafil/ 
  2. NHS (2022). Side effects of tadalafil. Retrieved on 3rd March 2025, from: https://www.nhs.uk/medicines/tadalafil/side-effects-of-tadalafil/

Whilst all of our content is written and reviewed by healthcare professionals, it is not intended to be substituted for or used as medical advice. If you have any questions or concerns about your health, please speak to your doctor.

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