I was taking Letrozole for 4 months but the joint pain was really bad in my knees. I was advised to stop this for 4 weeks and then start Anastrozole which I started last night. I've noticed that the Anastrozole is 1mg per day whereas the Letrozole was 2.5mg. What is the reason for the difference in dose, is this normal. Thankyou

  • Hi

    Thanks for getting in touch with us.  It’s only natural to have questions, especially when you have been started on a different type of hormone therapy.

    Anastrozole and Letrozole are 2 slightly different types of hormone therapy and the standard recommended doses are different for each of them. Anastrozole tablets only come in 1mg taken daily, where Letrozole tablets come in 2.5mg tablets taken daily.  The lower dose of Anastrozole doesn’t mean that it is less effective than the Letrozole dose.  Clinical research has shown that this is the most effective daily dose to take to prevent a cancer coming back.  

    Hopefully you notice a difference when taking Anastrozole and the joint pain isn’t as severe.  If you are still having problems with pain, please get back in touch with your consultant or nurse specialist as there are other options. 

    I hope this helps.  Please don’t hesitate to get back in touch if you have further questions.

    Take care,



    Cancer Information nurse specialist