Yep - got the raised, itchy rash. It took a few weeks too. Hypersensitivity (like an allergy) and had to cease the clexane. Only 0.1% of the population (or something stupid like that) experience this. Trust us to be special I continued on aspirin only. I am sensitive to heparin too, just in case they want to change you. There is a different anti-coagulant that is expensive and uncommon - but then, so are we!! You can take polaramine but I found it didn't do too much. I also ended up with some pigmentation in the raised / itchy areas which have improved over time.