Once it begins, the rash will usually clear on its own by 14-21 days.
Treatment is directed at controlling the itching. You may take oral antihistaminics like benadryl or zyrtec.Also apply calamine lotion as it has a soothing effect on the skin. You can apply OTC steroid cream but it is only helpful if applied right away, before blisters appear, or much later, when the blisters have dried up.