Doing warm saline gargles is a good remedy for blisters post extraction. Also to prevent blisters place baking soda over them and also rush to the dentist ASAP. Few other home remedies useful in the treatment of blisters are application of garlic gel capsule. Also application of lemon over the area is a good home remedy......For more info visit the link...http://www.identalhub.com/articlecategory-cold-sores-77.aspx