Dear @gerdboss You should try to keep the blister clean and not burst it ( intentionally or unintentionally) as the skin acts as a barrier, preventing bacteria from entering and cause an infection. You can apply antiseptic or antibiotic cream to the wound should the blister burst. There are blister plasters available in the pharmacy for you to paste on the blister to try make them subside. Should your blister continue to enlarge in size, you can consider visiting your General Practitioner and your GP can assist in draining the blister in a sterile manner, to make the blister subside. Hope you get better soon.