Blisters

A blister is a small bubble of fluid, often clear, under the top layer of skin. It forms when friction (rubbing) repeatedly stretches the skin, creating a tear between skin layers, which fills with fluid. A hard knock that damages blood vessels can cause a blood blister, which is simply a blister filled with blood.

Symptoms of blisters are:

• a lump that is filled with clear fluid or blood
• redness
• pain
• itchy skin

Blisters are commonly caused by friction or pressure, such as when wearing new shoes that 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 plants or the metal nickel

Some diseases and infections can also cause blisters, including:

• chickenpox
• 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 (Opens in new tab)

Depending on their cause, blisters can occur on the feet, hands, lips, mouth, torso (chest and back) or genital areas.

Serious blisters, and those caused by disease or infection, should only be treated by a doctor. You might need antibiotics or other medicines to treat the underlying condition.

A minor blister should heal in a week or two. If possible, cover and protect it and leave it alone to heal. The covering skin helps protect the blister from infection.

Self-care for blisters

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 wearing shoes or clothes places pressure on the blister, avoid wearing them.

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. It's best to check with a pharmacist first.

To drain a blister:

1. Wash your hands and the blister thoroughly.
2. Sterilise a clean needle with rubbing alcohol.
3. Pierce the edge of the blister and let the fluid drain out.
4. Cover with a clean non-adhesive dressing or bandage.
5. See your doctor if irritation, redness, warmth or pain increases.

You should seek help from your GP or dermatologist 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 swollen or red and is painful)
• you have diabetes or circulation problems

Blisters unfortunately can't always be prevented, especially if they are caused by a disease or infection. However, there are some tips to prevent friction blisters:

• Wear shoes that don't rub.
• Wear moisture-wicking socks to help keep your feet dry.
• Wear gloves when digging or gardening.
• Cover friction 'hotspots' with hypoallergenic adhesive tape or use anti-friction skin balm — see your pharmacist for advice.

• For blister first aid, visit the St John Ambulance website (Opens in new tab).
• If you have a rare autoimmune or hereditary blistering disease, you can contact the Australasian Blistering Diseases Foundation (Opens in new tab). Their A to Z of skin (Opens in new tab) list provides information about common skin conditions.
• You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.