If you have had the rash for a while and it is not spreading, then you may have already removed the plant's rash causing oil, urushiol. After showering for many days, your soap may have finally removed any oils that are not bonded with your skin. The rash is your body's reaction to this bond. If your rash is spreading then you may want to use one of our cleansers.
The purpose of the Tecnu Original Cleanser is to remove urushiol, but it does not include any anti-itch medication. Again, if your rash is not spreading, this product won't do anything for you at this point.