What causes blisters?
Blisters are commonly caused by friction or pressure, such as when new shoes repeatedly rub your heel.
Blisters can also be caused by injuries or damage from:
- insect bites or stings
- scalds or burns
- sunburn
- frostbite
- chilblains
- pressure ulcers (bedsores)
- contact with irritants that cause contact dermatitis, such as primula plants or the metal nickel
Some diseases and infections can also cause blisters, including:
- chicken pox
- shingles
- hand, foot and mouth disease
- impetigo or, ‘school sores’
- cellulitis
- genital herpes
- cold sores
- autoimmune diseases, such as pemphigus
- inherited diseases, such as epidermolysis bullosa
When should I see my doctor?
You should seek medical help if:
- you think your blister might be caused by a disease or infection — for example, if several blisters form without an obvious cause
- you have a blister on your mouth, eye or genitals
- you have blisters after a serious burn or sunburn
- your blister looks infected (it is full of pus, is inflamed and is painful)
- you have diabetes or circulation problems
How are blisters treated?
Serious blisters, and those caused by disease or infection, should only be treated under the direction of a doctor. You might need antibiotics or other medication to treat the underlying condition.
A minor blister that hasn’t burst will dry up in a week or 2. If possible, leave it alone to heal. The covering skin protects the blister from infection.
If you think the blister might burst, cover it with a loose bandage.
Cut a padded dressing into a doughnut shape (with a hole in the middle) and place it around the blister. Then, cover the blister and padding with a bandage.
If a blister has burst, wash and clean it. Leave the roof of the blister on and cover it with a plaster or bandage. A blister that has lost its roof completely can be covered with a special blister plaster. A pharmacist can advise you about this.
Don’t use home remedies such as green tea or vinegar because they are not effective.
You might decide to puncture a blister to drain the fluid if it is large and painful, but take care to avoid infection. To drain a blister:
- thoroughly wash your hands and the blister
- sterilise a clean needle with rubbing alcohol
- pierce the edge of the blister and let the fluid drain out
- wash the blister again
- apply an ointment, such as petroleum jelly
- cover with a bandage
Can blisters be prevented?
To prevent friction blisters, you can:
- wear shoes that don’t rub
- wear moisture-wicking socks
- wear gloves when digging or gardening
- cover friction ‘hotspots’ with hypoallergenic adhesive tape (again, your pharmacist can advise you) or use anti-friction skin balm