Hello i have an itchy labie majora and it only happens while im on my period and i have been tested for herpes and other sti's and i have none ?

If STD panel negativ: then likely you just have dry skin. this can be made worse by drying cleansers, soaps, detergents. try moisturizers like KY jelly but if not better see gynecologist

Itching: I suspect you are having a reaction to the extra moisture if your menses. You also could be having a local reaction causing the itching to panty liners or pads.

That's good!: At least you can be relieved that you don't have an STI/STD then! Itching near or on the genitals is not always due to an infection. Could be an allergic reaction to something you are using during your period - a wash or perhaps even a chemical in the pad you are using. Is there a rash? Has a yeast infection been ruled out? Be sure to see your MD during the symptoms not after they have resolved

Itching during mense: Blood changes the pH of the vagina so it is possible to having itching during your period. Another cause of the itching might be from using fragranced sanitary napkins which rub against your vulva, or super tampons which can absorb all of the normal lubrication one has. You can use an over the counter vaginal cream RepHresh, which will change the pH and perhaps relieve the itching.

Contact dermatitis?: If you are using pads or liners, you may have a dermatitis from them, Generic ones seem to be the worst. I have named this the "Generic Itch!" Also, use unscented laundry detergents and soaps, and do not over-scrub. Stay away from bubble baths. See how that works. If you still have problems, it may be that you get a little yeast infection at that time, which can be common around your period.

Blood: Blood can irritate your vaginal skin. Should this symptoms persist please see your doctor for full history and exam. Good luck