Hope -

I got this off the the EMLA Website http://www.emla-us.com/

In patients treated with EMLA in clinical studies, the percentage of patients in which local effects at the application site were observed included: skin paleness (pallor or blanching) 37%, redness 30%, a changed ability to feel hot or cold 7%, swelling 6%, itching 2%, and rash, less than 1%. These mild side effects generally went away by themselves within 1 or 2 hours.

The other posibility is that he may be allergic to the adhesive on the bandages that they used after the blood draw.

You will have to weigh the drug side effect vs. the blood draw itself.

Robin