Ocrevus side effect - strange groggy feeling

Symptoms and treatments
1

Updated 02/02/2026

Hi guys,

Had my first Ocrevus treatment 1m ago. Been generally fine, was tired after the treatment but not noticed any major side effects. One thing that is bugging me a little is this strange feeling of pretty constantly feeling like I’m about to come down with something. It’s so hard to describe but the best way I can is to compare it to the feeling you have when you’ve been sat in the sun for too long. Except I just get it sat on the sofa or sat at my desk working. It’s kind of a groggy feeling. Thought it could be hay fever so took anti histamines for a few days but no change. I’ve tried googling and nothing comes up but I don’t know if I’m describing it how others would?? I’ve never felt this exact feeling before but I’ve had it pretty consistently since the Ocrevus treatment. Maybe it’s just my immune system figuring things out? I’m not sure but would be interesting to know if anyone else has felt this way…

02/02/2026

I don’t know if me adding to this will do anything but worth a shot… still no change with this. Actually trying to ascertain whether it has got worse? I have noticed that any kind of exertion, mental or physical can bring it on. If I am completely relaxed for the whole day, I am less likely to feel it. Sometimes when it is worse I get quite nauseous. It is always worse in the heat, or if I have gone from one temp extreme to another, and when I have been sat at my laptop all day. Without a doubt comes on when I have direct heat on my head (when I blow-dry my hair, for example) but never when I go to hot yoga (???). I feel the urge to drink water when it happens but it doesn’t really give me relief. Sometimes eating something can help. I sound like a crazy person don’t I. If anyone else experiences this then I would be super grateful for your input. It’s super distracting and uncomfortable. Doctor said he thinks it’s fatigue from the MS and not a side effect of Ocrevus, which makes sense but I would love to understand it a bit better to try and stop it happening every single day. Oh and I have been fine so far in terms of infections etc, had 1 cold since my first treatment in June 2025, which cleared up within a week.

2

Hi Ssaf,

I’ve had similar, as it deletes half your immune system you will be susceptible to infections. I tend to always have “something” I still want to keep having it though. Don’t know if you have kids but I call my young Daughter patient 0 these days. :joy:

Separately, noting I’m not in anyway a medical professional (at all) there has been some studies which indicated certain antihistamines may be detrimental for MS progression (please do not take that as advice, I’m not certain it has been confirmed and it will maybe be specific ones, talk to a professional).

I’d say if you have an MS nurse talk to them, there is also the hotline on here. Since it’s your first time it might be good just to talk it out. We are all in a way finding out and aren’t professionals so researching is just another thing to the fun of having MS. It’s easy to go into stress/research spiral and be ill.

Cheers,
Andrew