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Humira and antibodies

My 10 year old daughter started Humira a few months ago after failing Remicade. She's on the 20mg shots every other week and weighs 70 pounds.

Her GI just did a test to see the Humira levels and antibodies and the Humira level came back as 4.2, and usually 5.0 is what is considered a therapeutic level.
As for the antibodies, he said she was borderline on the antibodies at 2.4 (he said 1.7 was normal). I wrote the numbers down but they don't mean anything to me.

He suggested two possible options. Upping her to 40mg instead of the 20mg. Suggesting that she was being under treated and that antibodies can develop in that case (like if someone misses a dose). With the hope that the higher dosage would make her feel better (she's still having symptoms, though not all the time) and help with the antibodies. It feels a bit counter intuitive. That she's displaying some antibodies and that more of the drug could potentially help that instead of making it worse. He would then retest her levels in a month. But of course there is always the risk that the antibodies get worse and she'd have to move on to another drug. On the flip side, if it worked it would avoid having to add yet another heavy duty drug to her medicines.

The other option is adding methotrexate to her current Humira regime.

Does anyone have any experience with Humira and antibodies?

my little penguin

Staff member
The lower levels in the body the more likely to develop antibodies so if she doesn’t have enough humira in her system the body fights it
Higher levels and the body fights it’s less

Methotrexate is a lower level drug but sometimes helps with stopping antibodies from forming other studies state it doesn’t help at all but helps boost the humira
Ds was on humira 40 mg plus mtx at 68 lbs

Dosing got humira is higher for jia kids than crohns
So at 66 lbs they switch to 40 mg
Vs 87 lbs for crohns

They have been using humira much longer in jia
Just a preference
Similarly they use remicade first for crohns kids

Ds was on both remicade for 8 months (reaction. )
Then humira for 5 plus years with mtx for 4 of them

Juvenile Idiopathic Arthritis or Pediatric Uveitis
The recommended dose of HUMIRA for patients 2 years of age and older with polyarticular juvenile idiopathic arthritis (JIA) or pediatric uveitis is based on weight as shown below. MTX, glucocorticoids, NSAIDs, and/or analgesics may be continued during treatment with HUMIRA.

(2 years of age and older)
10 kg (22 lbs) to <15 kg (33 lbs)10 mg every other week
(10 mg Prefilled Syringe)
15 kg (33 lbs) to <30 kg (66 lbs)20 mg every other week
(20 mg Prefilled Syringe)
≥30 kg (66 lbs)40 mg every other week
(HUMIRA Pen or 40 mg Prefilled Syringe)


Well-known member
Second ^ on higher dosing but also it is very, very common to use methotrexate with a Humira or Remicade to prevent the formation of antibodies. After about a year or so, a lot of GI's will consider removing the methotrexate. Both of my girls used methotrexate with Remicade and then stopped after a number of years. The anti tif's have the best track record with pediatric Crohn's so personally I would do whatever I had to in order to prevent antibodies from forming.

Good luck!
We don't have Humira experience, but my daughter had a similar experience with Remicade after she had been on it for 2 years. She was flaring, and when her levels were checked, her Remicade level was on the low side, and her antibody level was detectable (but low) for the first time. We decided to both add methotrexate and increase her Remicade dose, and she responded really quickly to the change. She's continued with Remicade and methotrexate for 3 years since then she hasn't had any more detectable antibodies.


Staff member
I agree - definitely up the dose. The reason she is making antibodies is because there isn't enough of the drug in her blood - or at least, that is how it was explained to us. If her body is metabolizing Humira too fast, you risk having periods of time where there is no Humira in her system and obviously that is not good and can lead to antibody formation. So increasing the dose would benefit her in two ways - 1) She'd have therapeutic levels of Humira in her blood at all times and 2) Because trough levels of the drug would increase, her body is less likely to make antibodies to the drug.

Methotrexate is another option. It is used to prevent antibody formation and/or as a therapy. If it's just for antibodies, then generally a lower dose is given. If it's meant to be a "boost" with Humira because her disease isn't fully controlled, then you'd typically use a higher dose.

Both options are safe...if it were my kiddo, I'd probably increase her Humira dose first, since she is over 66 lbs and clearly has low Humira levels. But MTX is also thought to work by increasing trough levels of the biologic in the blood, so that may work too. Some kids have side effects with MTX, but most tolerate it without issues.

Humira has been used a LOT in the rheumatology world - in kids as young as 2 years old. It's definitely safe, especially since her antibody levels are just barely high. Unlike Remicade, it's a humanized protein so allergic reactions are much rarer than with Remi, which is made with mouse protein.
Thanks for all the responses. I really appreciate all the parents sharing so much IBD knowledge.

We upped her dosage to 40mg every two weeks and did blood work after a month of the new dosage. Her Humira levels are now therapeutic (5.4), but her antibody levels went up slightly as well. From 2.4 to 3.8. We discussed adding Methotrexate again, and her GI didn't want to add it (though he wasn't dogmatic about it at all, was more inclining in that direction because of the side effects, ect...). He said if you talk to ten different Pediatric GI's you'll get 5 who would add it in her case, and 5 who wouldn't (mostly to illustrate that there is no easy answer). I definitely don't want to add more drugs to her system, but I am worried about her rejecting Humira and losing that option.

I'm contemplating getting an online second opinion from Boston Children's. Has anyone had good experience doing that? Though even with that it takes 3-4 weeks and I'm not sure if that would be soon enough. My concerns are also elevated since she developed a few small hives around the injection site last time. She also had some blood in her stool yesterday and spiked a fever (which could easily be a virus but she also has gotten fevers with flares in the past).

I wish there was a more clear cut protocol. She's scheduled to get blood work done again in about two and a half months.
I'd be tempted to at least try methotrexate, since it looks like you may be getting close to losing Humira as a treatment option. My daughter does have side effects with it, but they are pretty minor. You can always drop it if your daughter has problems with it. Let us know if you'd like more info--lots of kids on the forum are on methotrexate, or have been on it in the past.


Staff member
I would also try MTX - it's true some kids do have side effects and have trouble tolerating it, but many feel perfectly fine. My older daughter has been on MTX for about 10 years now. Every so often, she tries to decrease her dose and promptly flares, so we know it really works for her! The only side effect she has is mild fatigue the day after the shot. She used to get nauseous but Zofran helped with that and over time her nausea went away.

Some of the tricks we used to help her tolerate it better - switching from the pills to the injection, doubling the dose of folic acid she was taking and Zofran for nausea. She has always done the shots herself, starting at age 15 I think - it's a teeny tiny needle and she says it's basically painless. She also always did the shot before bed - the idea is to let them sleep through the side effects.

Considering there are so few options for kids, I'd try to maximize your daughter's time on each biologic, and since MTX might help with that, I'd say it's worth a shot.


Staff member
In terms of the Boston Children's records review...someone on here did it recently, but I can't remember who...

I'll tag @crohnsinct since she visited BCH with her kids and knows a lot about antibodies and drug levels.
I would agree with the others who suggest adding in Methotrexate. Lucy was on the combo of Humira and Methotrexate for 5 years, she had some side effects to the methotrexate initially but as time went on these completely subsided and she tolerated the combination very well.
The good news is that D10 now has no detectable antibodies to Humira after a few months on the 40mg every two week dosage. So I had my fingers crossed that the flares (two towards the end of 2019, which necessitated a round of prednisone for each flare) would stop in the future. I thought things had stabilized since everything had been okay for the last few months. But she spiked another fever (102) two weeks ago the night before she was due for her Humira shot. That seems to be part of the pattern. In January as well she spiked a fever the night she was due for her Humira shot.

It doesn't feel like the Humira is totally working. Her GI doesn't want to put her on steroids again, and had me give her the Humira a few days into the fever anyway since it was consistent with her pattern and she had no viral symptoms. That seemed to help but she's still running a low grade fever--99.8 or 100.4 or thereabouts a week later.

I'm wondering if she either needs to have the Humira more frequently or needs to add MTX to her regime.


Well-known member
Yeah...with Crohn's you can get inflammatory fevers. Sounds like that is what she might be getting. If they don't happen until right before the next shot then it could be she is just metabolizing the meds faster than the regular person. Active inflammation could add to metabolizing the drug quicker. I think you are right and that she either needs Humor weekly or to add mtx. Of course the GI would also have to rule out any infections that might be causing this particular prolonged fever, especially given the coronavirus goings on.

my little penguin

Staff member
For ds we found humira can be given
Every two weeks
Every 10 days
Every week
Highest dose was every 5 days
How are her inflammatory markers ?
Have you had them drawn the day humira is due ???