White blood count

Hi all

My white blood count was 4.2 in November, and now is 3.1.

Should I be concerned? I don’t feel ill, just a little tired, but put it down to the heat (have moved to NZ).

Medication I am on is techfidera (240mg).

hi neil

it is expected to have a lower white blood count with tecfidera.

that’s why we have frequent blood tests.

check with your ms nurse if you are still worried.

carole x

Thanks [Edited]

But how low is low?

Mine haso dropped by 25% in fI’ve weeks after being on same medication for 18 months.

hi again caroline

i’ll look for my last letter from my ms nurse and let you know what my last results were.

are you having your blood done every 3 months?

if so you should be ok because i was assured that it wouldn’t be allowed to drop to dangerous levels.

we get taken on tec if it does.

carole x

Hi, my count was 0.44 last December & I have to have another test this week. My consultant said she doesn’t like it to go below 0.5. I am also on Tecfidera & when I saw her last it was 0.6 so I assume she will take me off Tec if it isn’t improved this week. I am hoping it’s gone up as I don’t want to change me dmd. Fingers crossed!!!


The point about your white blood count is really related to the different types of white blood cells.

In particular, the doctors are concerned about your lymphocytes, these are the WBCs which fight viruses. The normal range is somewhere between 1.0 and 3.5 (multiplied by some kind of fraction and another mathsy thing!) They also look at neutrophils, which are the WBCs that fight infections. The total that your WBC comes to is important, but not as relevant as the detail.

When you take Tecfidera, your lymphocytes are supposed to be depleted for a while by the drug, then rebound back to a normal level, even if it’s a low normal level.

Doctors become concerned when your Lymphocytes go below 0.8 (some neurologists use this as a cut off point) or more particularly, below 0.5 and stay there or lower. If your lymphocytes go this low, you will normally have to stop taking the Tecfidera.

The reason they check it is to do with PML, the nasty brain virus which you can catch if you have JCV antibodies and low lymphocytes. The doctors don’t check your JCV status when you take Tecfidera, they check your lymphocytes level instead.

This is what happened to me, almost 18 months ago while I was on Tecfidera, my lymphocytes dropped to 0.4 and stayed there for 3 months, when I stopped the 'Tec. I then had my blood tested every month and it bounced up and down from 0.4 to 0.6. After about a year, my blood finally reached 1.0. That was in November, I hadn’t had my blood tested since then till last week when I had a virus and my lymphocyte count was 0.2. I don’t know why. I’m hoping it was the virus which caused the drop.


Thanks for the answers.

I am the same as you helly, fingers crossed I don’t need to change Meds. All the best x

Blood tests done for immigration ( moved to nz), so will book another blood test next week to see what the wbc I then.

Carole just new to new Zealand, will have wait till visa sorted then will be in the system.cheers for your response

Sssue thanks for such a detailed reply.

Tecfidera will knock your WBC down a bit, for the first 3 to 6 months at least. But it should rarely get to an unacceptably low level.

It should then start to recover, at the very least within a range deemed ‘normal’.

It is when it fails to recover, that it is considered a risk / problematic.

Tecfidera users should be having the blood anc liver function tested every 3 months for at least the first year to guard against such risks. It is highly foolish not to.

Hi Paolo, I hope you’re doing well today. I have had all the tests since being on Tec since Feb 2016 & only have what’s considered too low white count since December 2016. So although I feel ok I’m hoping maybe I had a infection & that it will go up to an ok level soon.