probably the most common cause of outer vaginal itching would be yeast. yeast loves warm dark and moist places and the vagina really fits the requirements. yeast is present in our environment so you do not have to catch it from someone. it can just happen. you may want to consider using one of the many over-the-counter vaginal yeast medications to see if it helps. another possibility would be a contact dermatitis. if you recently changed laundry detergents dryer softeners or soaps this could be a culprit as well. if home treatments are not helping you will need to see your health care provider for a proper examination diagnosis and treatment.
i'm 41 and have had moderate outer vaginal itching but no discharge. haven't had sex in 2 months. same partner so no worries of std. just very uncomfortable and not sure what would cause this.