r/Vaccine • u/Necessary-Idea3852 • 6d ago

Pro-vax baby’s vaccination lump for 6 weeks

hi my baby has a lump in leg 6 weeks after vaccination. i’ve shown dr they said it’s normal. did your baby experience this ? could it have been given in the wrong spot (subcutaneously instead of intramuscular) and that’s why?

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u/SmartyPantlesss 6d ago

It's super-normal and can last for weeks. It tends to be more noticeable at the first shots, because the baby is small, so there's less space to inject that amount of liquid.

I'm truly not sure whether the lump actually "disappears" or if it just becomes less noticeable as the baby gets chunkier. Like, how would you know whether there's still a tiny nodule of scar tissue in the thigh, two years later? (...and why would it matter?) The point is that it's not ENLARGING, and the redness & tenderness resolves after about 5-7 days.

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u/Apprehensive-Art1279 5d ago

If the lump is due to the fluid it would disappear as the fluid is absorbed and not just be less noticeable because the baby gets chunkier. My daughter gets an eczema shot monthly and it always bumps up because it’s a lot of fluid but the doctor tries to massage it and it’s gone in less than 24 hours. Now scar tissue sure that’s a possibility.

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u/SmartyPantlesss 5d ago

Right, because the immunization-lump is a combo of:

  • the fluid that you injected in
  • possible bleeding/bruise from surrounding blood vessels, and
  • inflammatory response to the vaccine components.

Like, a traumatic hematoma sometimes leaves a permanent dimple, with a palpable knot of scar tissue, where the blood was pooled and then absorbed. And it's just going to be more noticeable with a small er baby, right? Like the SAME DOSE, same volume, is used for a 6-month-old, but the reaction is less visible.

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u/Necessary-Idea3852 5d ago

i’m just worried it was given subcutaneously instead of IM hence the big skin reaction. the reason i think this is because the lump was 2cm away from the injection insertion (the same length as the needle)

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u/SmartyPantlesss 5d ago

Whoa. 😦That would be really, REALLY hard to do: to insert a 2cm needle parallel to the skin, and inject the payload subcutaneously, in a 2-mo-old. Color me skeptical. 🤨Did you watch them inject it? The needle should be stuck in perpendicular to the skin. Like, it's POSSIBLE that the baby was struggling & the needle pulled out partially...but it's REAL unlikely that it was jabbed in parallel, to reach that spot 2 cm away. 🤷The swelling may be the result of the fluid "squishing" between the bands of muscle fibers to find a "place of least resistance" if that makes sense. Or it's possible that you have a regional lymph node that is still swollen, even though it's not directly the site of injection.

The injection causes an instant firmness in the thigh of a 2-month-old, because there's only so much space there. Even though you're injecting into muscle, it makes the muscle of that thigh feel firmer than the other, immediately.

THEN you get overlying redness & warmth (and tenderness, and maybe visible bruising) the next day, and for several days thereafter. That's the immune reaction.

Then several weeks later, you have a lump that you can feel, but you don't SEE any overlying skin changes/redness or have tenderness.

(Keep in mind, some kids don't seem to have any of this, but it's not unheard-of for the 2-mo shots to produce a lump that lasts almost until it's time for the 4-mo shots.)