Evening Primrose Oil has a reputation as a women's oil because of it's apparent ability to stimulate the production of prostaglandins which assist in the healthy functions of body tissues, in particular menstrual cycles, cholesterol levels, inflammation, immune system, and hormonal balances. It's not an essential oil but it's effectiveness has made it quite popular lately. It's purported to be effective on rheumatoid arthritis, heart disease and mental disorders.
In aromatherapy, it is used as a carrier oil when used to assist the endocrine system by having an obvious soothing effect on the emotions, while in turncreating a stronger resistance to stress, which is known to cause and aggravate many conditions. If you're using it for this or as an anti-wrinkle treatment, you would apply it topically, otherwise use it in an incapsulated form.