Tadalafil is used to treat erection problems. Find out how to take it safely and possible side effects. Tadalafil is also called Cialis.

On this page, you can find the following information:

Type of medicine Also called
  • Belongs to a group of medicines called phosphodiesterase type-5 (PDE5) inhibitors
  • Cialis®

What is tadalafil?

Tadalafil is used for men with erection problems (erectile dysfunction). It increases blood flow to the penis, to help achieve an erection. To work well, tadalafil needs to be taken 30 minutes or more before sex. This gives it enough time to get into the penis to work. 

Tadalafil belongs to a group of medicines called phosphodiesterase type-5 (PDE5) inhibitors because it blocks the enzyme called phosphodiesterase type-5. In New Zealand, tadalafil is available as tablets. 

How well does tadalafil work?

Tadalafil works well for most men with erectile dysfunction, helping sustain an erection for penetrative sex in about 7 out of every 10 users.

  • tadalafil does not work so well for men with diabetes, those who have had prostate surgery or severe erectile dysfunction.
  • If tadalafil doesn't work, other PDE5 inhibitors such as sildenafil or vardenafil may work better.

What can affect how well tadalafil works?

Some things may affect how well tadalafil works. These include:

  • no sexual stimulation
  • trying sex too soon after taking tadalafil
  • drinking alcohol, as it can lessen the sexual response
  • anxiety.

When is it not safe to take tadalafil?

Medical conditions

Tadalafil may not be suitable for everyone. Tell your doctor or pharmacist if you have or have had any of the following:

  • any heart or blood vessel problems
  • leukaemia (cancer of the blood cells)
  • multiple myeloma (a cancer of the bone marrow)
  • any disease or deformity of your penis
  • low or high blood pressure
  • sickle cell anaemia
  • bleeding disorders
  • stomach ulcer
  • liver problems.


Tadalafil should not be used if you are taking medicines called NITRATES.
Nitrates are usually used for chest pain (angina) and other heart conditions.

Nitrates and tadalafil should NOT be taken together, as both medicines together can cause a dangerous drop in blood pressure and collapse. Nitrates come in a variety of forms. Examples of nitrates are:

  • isosorbide mononitrate (Ismo 20®, Ismo 40 Retard®, Duride®)
  • sprays such as Glytrin® or Nitrolingual® spray 
  • patches such as Nitroderm TTS®
  • ointment such Percutol®.

If you are taking a medicine called an ‘alpha blocker’ (such as doxazosin, terazosin, prazosin) your dose may need to be changed.

How to take tadalafil

  • Tadalafil tablets come in different strengths – 5 mg, 10 mg and 20 mg.
  • Tadalafil can be taken either on-demand (before sex) or every day. Your doctor can advise if everyday treatment is best for you.
  • For the ‘on-demand’ dose, 10 mg or 20 mg should be taken 30 minutes or more before you plan to have sex (it may still work 36 hours later). Do not take more than one dose in 24 hours.
  • The everyday dose is 5 mg or 2.5 mg once a day. The once-daily dosing is for people who have sex more than twice weekly. It will cause an erection whenever sexually stimulated. Tadalafil must be taken everyday and for up to 1 week for a full effect.
  • You can take tadalafil with or without food or alcohol. However, drinking alcohol may affect your ability to get an erection, so avoid excessive drinking.

Side effects

Like all medicines, tadalafil can cause side effects, but not everyone gets them. 

Side effects What should I do?
  • Blocked nose
  • A sensation of redness and warmth or burning of the face (called facial flushing)
  • These will pass quite quickly
  • Headache, muscle aches and pains
  • Tell your doctor if troublesome
  • Indigestion 
  • Tell your doctor if troublesome
  • An erection that lasts longer than 4 hours
  • Painful erection
  • Chest pain 
  • Rash or swelling of the face
  • Sudden problems with your eyesight such as loss of vision, in one or both eyes
  • Sudden loss of hearing  
  • Tell your doctor immediately or ring HealthLine 0800 611 116

Learn more

Cialis® Medsafe Consumer Information (NZ) 


Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 20 Feb 2017