Why would lidoderm pain patch have a reaction on a pulse rate?

Unusual: Lidoderm patch causes local pain relief and typically does not enter blood stream or build up levels in the body. I suppose if one used several patches at a time, there might be enough to affect pulse, but this too would be very unusual. Doubt allergic response unless local skin rxtn. Search for another explanation.

It shouldn't : If used as prescribed. Explore other reasons and make sure you are using it as prescribed. If it still happens, consider a different medication.