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CLL Support Association
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High fever as side effect of Ibrutinib ?

Hi, I'm new here and follow this blog with great interest.

I had 6 cycles of FCR 5 years ago which gave me 5 years of a nice remission.

For the last 2 years I am on monthly IVIG because of frequent pneumonias. Helped really good.

Now my CLL has returned .

4 months ago a low grade fever started , about 37.5C . A chest X-ray showed swollen lymph nodes all over so my hemato started testing for CLL and my FISH brought a bad surprise - TP53 deletion. So they asked me to join an Ibrutinib-Acalabrutinib trial group.

I started Ibrutinib 4 days ago. Since then I get very high fever - almost 40C - every evening. My head is "burning" and I feel very weak. I was hospitalized for one day and went through all the blood, urine tests and chest X-RAY. Found nothing, except a very high CRP - 47. I received iv antibiotics but no change . My hemarologist does not think the high fever is a side effect of Ibrutinib.

I do think it is. I have no other infection .

Did anyone suffer from high fever as a side effect from Ibrutinib ?

Thank you for your support.

8 Replies

Mayo Clinic site: mayoclinic.org/tests.../c-r...

You may have already read something about CRP high levels. It sounds scary--inflammation somewhere in your body--it could be arthritis or something not so scary, but Ibr. does have a history of side effects that can be serious. If you continue to feel uneasy, insist on another look by the hematologist, or see a cardiologist.

Others may be able to be more clear on what possibilities or likely with Ibr. I have no experience with it or with trial situations.


High CRP can be due to infection. Try to get blood culture report.

My CRP is 78 and I have lung infection. Taking antibiotics.

1 like

Did your blood tests include uric acid? Hyperuricemia can be associated with a high CRP and also with a fever if you are experiencing TLS tumor lysis syndrome. I had a very high ALC at 220 when I started ibrutinib, so I was pretreated for a week with allopurinol to lower existing uric acid, and was also infused with rasburicase by IV on Day 1 and 2 of ibrutinib to prevent a new uric acid formation and TLS. My uric acid level was slightly high even before I started treatment, and I did have a 1 degree rise in body temp the first day and my face flushed for a short time during infusion. Are you taking allopurinol?



I didn't have a fever when I started Ibrutinib and I don't think it's a recognised side effect.

This is the Ibrutinib website -

imbruvica.com/cll/side-effects and if you want more technical information then this one is very comprehensive


Please go back to your doctor if you don't improve very soon.

best wishes

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I am on Imbruvica since mid Jan 17 , and due low IvG got recurrent infection of lungs like Pneumonia ( like you) and last month got Fungal infection in lungs ( due bacteria) and also water in right lung which on analysis contained 44% lymphocytes. In all cases had high grade fever which acted as a sign of infection somewhere in body -- and not account Imbruvica. In short pls ask your Onco doc or better consult a GP to locate source of infection.

I am now on monthly dose of IvIG to boast immunity and thus to avoid other infections.

Take care


I've been on ibrutinib for over 3 years and have never had a problem with high fever. At first, I was taking ibrutinib plus rituxan IV every 4 weeks, & I would run a low-grade fever (less than 100F/37.8C) in the evenings for about 1-2 weeks after the rituxan IV but after the rituxan was stopped after about 9 months, the fevers stopped, too.

Hmm ... it certainly sounds like the cause of the fever is something else.


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Fever is one of the signs of lymphoma progression. My wife took Ibrutinib for over a year without any fever. However all patients are different and respond to cancer treatments differently.


I have not had that. I take a night after dinner or before bed and that seems to help side effects.


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