Q&A 34: ofatumumab and urinary tract infections

Case study and questions

I have SPMS, but my neurologist put me on ofatumumab (Kesimpta). Neither of us expected much good from it, so when I started getting recurrent and severe UTIs after three months, i.e. five infections in two months, we agreed that I should discontinue it. My GP has subsequently put me on prophylactic nitrofurantoin (50mg a day), which appears to have prevented any more infections while my immune system recovers. The plan is to stop the nitrofurantoin after four months. But I'm getting bad indigestion and very uncomfortable after every meal. Is this a common side-effect of nitrofurantoin?

Is there any chance that ofatumumab (Kesimpta) causes UTIs via a pathway other than immune system depletion? When will it 'wash out'? When can I stop taking nitrofurantoin? My GP raised this question. I could try stopping it, but I don't want to start getting UTIs again suddenly. I only have one kidney and need to protect it.

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For clarity, I have deconstructed your case into five parts, which I will address separately.

Part 1: I have SPMS, but my neurologist put me on ofatumumab (Kesimpta). Neither of us expected much good from it, so when I started getting recurrent and severe UTIs after three months, i.e. five infections in two months, we agreed that I should discontinue it.

Part 2: My GP has subsequently put me on prophylactic nitrofurantoin (50mg a day), which appears to have prevented any more infections while my immune system recovers. The plan is to stop the nitrofurantoin after four months. But I'm getting bad indigestion and very uncomfortable after every meal. Is this a common side-effect of nitrofurantoin?

Part 3: Is there any chance that ofatumumab (Kesimpta) causes UTIs via a pathway other than immune system depletion? 

Part 4: When will ofatumumab 'wash out'? 

Part 5: When can I stop taking nitrofurantoin? My GP raised this question. I could try stopping it, but I don't want to start getting UTIs again suddenly. I only have one kidney and need to protect it.

Answers