Can salonapas pain patch or pain creams cause irritation, itching to the skin and blister if left on too long? Or allergic reaction? Treatment?

Pain patch. The pain patch is not to be used for greater than 3 days, or if you are sensitive to any of the ingredients. It is not meant to be used while you are sweating or on damaged skin. A contact or allergic dermatitis is possible. If you feel like you are having a reaction, remove the patch and wash the area with soap and water and do nothing. Avoid contact with irritant. Visit MD if no improvement.
Yes Salon pas. commonly has aspirin (salicylic acid) which is a common skin irritant if used repeatedly in the same location. Also, the material the patch is made of can cause a local allergic reaction. Treatment for blistered skin is make sure it is free of irritant, lightly washed with mild soap or just water/vinegar combination, and hydrocortisone applied to site.