Hello and welcome,
It seems that the blister
is a reaction to your sanitary napkins or tampons or is due to the wetness of periods.
Change the brand of sanitary napkin or tampon that you use and use a good reputed brand that is hypoallergenic.
If it is due to wetness, Try changing the pad three to four times in a day. Similar with the tampon when the flow is more. Also clean the labia with antiseptic warm water or antiseptic wipes twice daily. Apply some medicated powder like neosporin
to the labia once a day. Try to keep them open to air at night for a while to allow the part to dry up. This will help damage ti the sensitive part and prevent blister formation.
Hope this satisfies your query.
Thanks for using HCM.
Feel free to ask any more questions that you may have.
Dr Madhuri Bagde
Consultant Obstetrician and Gynecologist