How to treat a blister: when to leave it and how to cover it

A blister is the skin's own dressing. Leave it unbroken, keep it clean, cover it, and stop whatever rubbed it, and it usually heals in about a week. Below, one example runs from the first blister to a healed heel, with a drawing for every step.

When to get help

Call 111 or get help from 111 online if (NHS):

• it looks infected: hot, with green or yellow pus, or red skin around it (redness can be harder to see on brown or black skin)
• it is very painful or keeps coming back
• it is in an unusual place, such as the eyelids, mouth or genitals
• several blisters have appeared for no reason
• it was caused by a burn or scald, sunburn or an allergic reaction. For burns, see Minor burn or scald

The NHS warns not to ignore an infected blister: without treatment it can lead to a skin or blood infection.

Diabetes or poor circulation. A foot blister may not heal easily. The Royal College of Podiatry says to see your podiatrist for advice. Don't drain it yourself, and ask a pharmacist or your GP practice before using blister plasters.

Our example: Amira's new walking boots

Every step below follows one story, and each drawing shows that exact moment. On a Saturday walk, Amira's new walking boots rub the back of her right heel. At home she finds one oval blister about the size of a fingertip, filled with clear fluid. On Monday it bursts, and by the end of the week it has healed. One "what if" drawing shows what an infected blister looks like.

Part 1: A blister that hasn't burst

1. Look at it.

   

   In our story: Amira rests her foot on a folded towel and looks at the back of her right heel: one smooth oval bubble of clear fluid, the skin around it only faintly pink.

   Clear fluid is the usual friction blister. Red or black fluid is a blood blister, from small blood vessels damaged under the skin; treat it the same way and don't pop it. Green or yellow pus means infection: see When to get help (NHS).

2. Wash gently and pat dry.

   

   In our story: Amira washes round the blister with mild soap and water, then pats her heel dry with the towel.

   Keep the blister as clean as possible: wash the skin gently and pat it dry (NHS). Don't rub.

3. Cover it.

   

   In our story: Amira smooths a hydrocolloid blister plaster over the blister, running her fingertip round the edges so there are no wrinkles.

   Use a soft plaster or padded dressing (NHS). A hydrocolloid plaster, a moist gel dressing, can protect the blister, ease the pain and help it heal faster (NHS). The skin must be clean, dry and free of cream or the plaster won't stick. Follow the pack on how long to leave it on.

4. On a pressure spot, add a padded ring.

   

   In our story: For the walk to work, Amira adds a ring of soft felt round the plaster, with the blister in the hole, so her shoe presses on the ring and not on the blister.

   The Royal College of Podiatry recommends this "doughnut" of padding for a blister on a heel, toe or sole. Tape it down or cover it with a soft gel dressing.

5. Don't pop, prick or peel it.

   

   In our story: That evening the plaster comes off when she showers. Looking at the bare blister, Amira is tempted to prick it with a sewing needle, but puts the needle down on the towel. The blister stays closed.

   The NHS says not to burst a blister yourself, peel off the skin or pick at the edges. The skin on top keeps germs out while new skin grows underneath, and the fluid usually goes down by itself. See Should you ever drain a blister?

Part 2: If it bursts

1. Wash your hands, then let it drain.

   

   In our story: On Monday the blister has burst. Amira washes her hands, then lets the clear fluid drain onto a square of clean gauze.

   Wash your hands before you touch a burst blister, and let the fluid drain before you cover it (NHS).

2. Leave the loose skin on.

   

   In our story: Amira cleans round it gently and leaves the thin flap of skin lying flat over the pink skin underneath.

   Don't peel the skin off or pick at the edges (NHS). Laid flat, it works as a natural dressing.

3. Cover it again.

   

   In our story: Amira puts a new hydrocolloid plaster over the burst blister and presses the edges flat.

   Use a soft plaster, a hydrocolloid blister plaster or a soft gel dressing. The Royal College of Podiatry suggests an antiseptic ointment under the dressing for an open blister; if you use one, follow the label, or ask a pharmacist.

Part 3: Until it heals

1. Check it every day.

   

   In our story: By Friday the blister is flat and dry, with just a faint pink patch where it was.

   Change a normal plaster if it gets wet or dirty. A hydrocolloid plaster can usually stay on until it starts to peel at the edges; follow the pack. Most foot blisters clear in 3 to 7 days once the rubbing stops (Royal College of Podiatry).

2. Watch for infection.

   

   In our story: What if it had become infected? It would look like this: yellow pus, and red, swollen, hot skin spreading round it. Amira would call 111.

   Spreading redness, more pain, warmth, swelling or pus mean it may be infected. Call 111 or get help from 111 online (NHS). If you also feel very unwell, see the box at the top.

3. Stop the rubbing.

   

   In our story: Amira leaves the new boots by the door until her heel has healed and wears soft trainers with thick socks instead.

   Don't wear the shoes or use the equipment that caused the blister until it heals (NHS). Then wear new shoes for short periods at first.

Should you ever drain a blister? Sources disagree

• The NHS says not to burst a blister yourself. A GP might burst a large or painful one with a sterilised needle.
• Mayo Clinic (US) says a very painful blister can be drained at home, leaving the top skin on, with a needle cleaned with rubbing alcohol, and that people with diabetes or poor circulation should take extra care.

Our advice for UK readers: follow the NHS. If a blister is so tense and sore that you can't walk or work, ask a pharmacist or your GP practice rather than draining it yourself. Never drain one yourself if you have diabetes, poor circulation or a weakened immune system.

If something goes wrong

No blister plaster? Use a padded ring

Cut a piece of moleskin or foam about 2.5 cm (1 inch) bigger than the blister. Fold it in half and cut a half-circle from the fold, so it opens out with a hole the size of the blister. Stick it on with the blister in the hole and cover it with gauze. Mayo Clinic describes this method; it keeps pressure off the blister while you walk.

Related: Minor burn or scald and How to clean and dress a small cut or graze.