I used to use some weight loss patches (years ago) and got the same reaction. It is a raised welt, red, hot, and yes... it itches like mad. I agree about checking into a possible latex allergy, but my money would be on an alergy to the adhesive on the patch. It will take a while for the marks to go away, but they will (We are talking maybe a few months).

Mine is so bad that I cannot use bandaids unless it is a particular brand (can't remember what at the moment) and to top it off, they have cute little pictures of Tigger, Poo, the Little Mermaid... etc. I just tell people I have kids. LOL.

On a related note, I just discovered that the adhesive that is used in most patches/bandaids is derived from pine sap. I am very allergic to pine trees, so for me at least, it is a decent explaination as to why I break out.