Blisters due to burns are covered in another section.

Friction Blister

Scenario:
Mountain bike blisters are usually on the hands, from fighting the handlebars through rough terrain. Wearing gloves helps avoid them, of course. Foot and toe blisters from ill-fitting shoes are the most prone to complications. Moleskin can help prevent blisters on areas prone to rubbing, such as the heel.

Description:
A blister occurs when the outer (epidermis) layer of the skin separates from the fiber layer (dermis). The skin will regrow from underneath. The loose skin is dead. Blisters can occur from heat, frostbite, chemical injury, or friction. Unless infection occurs, blisters usually heal quickly.
Broken friction blister on the palm.
Broken friction blister on the palm.
Immediate care:
Whether you should leave the blister or snip it away depends on where it is: Will there be pressure on the blister? Will there be chafing? In general, a friction blister is most comfortable if you leave skin intact over it. If the blister is uncomfortably tight, or if its location means it will have pressure on it as you work, you may need to let the fluid out.
Typical biker's handlebar blister at the base of the thumb, facing the index finger. This blister has already popped. After cleaning, we apply an antibiotic ointment.
Typical biker's handlebar blister at the base of the thumb, facing the index finger. This blister has already popped. After cleaning, we apply an antibiotic ointment.
Putting the skin back in place can make the blister much more comfortable.
Putting the skin back in place can make the blister much more comfortable.
You should either leave the blister alone, or open it completely. Don't stick a pin in it (this commonly causes infection). If you plan to open the blister, clean the area with Betadine. Cut at least half of the blister open. Apply antibiotic ointment. Now plaster the flap back into position. Apply a dressing that puts light pressure on the blister area.

The skin is left in place to protect the sensitive basement layer below. It's also much more comfortable with the skin protecting the sensitive layer underneath. Using the ointment as "glue," the flap is smoothed back in place.

The blister must be protected from further trauma. While a bandaid (as shown) can protect an office worker, a biker needs more robust protection. Fashion a dressing using a non-stick pad and roller gauze. (see section on dressings )
Cover the blister.
Cover the blister.

Ongoing care:
Keep the wound clean, dry, and protected from chafing and bumping. Change the dressing every day, or whenever it accidentally gets dirty. After two days, you can resume washing (but always put a dry bandage on afterwards). When the wound looks like normal skin and feels like normal skin you can stop bandaging. Expect about 7 to 14 days for healing. The old skin can be snipped
off when you're sure the area is healed.

Watch for:
See the doctor if there is redness around the wound, red streaks, swelling, drainage, fever, tender bumps in the groin or armpit upsteam from the wound, or an unexplained increase in pain or tenderness.  See section on infection.

Blood Blister
Description:
A blood blister usually develops following a smashing or pinching injury. There's a small skin injury that pumps blood between the skin layers, raising up a blister of blood. If there are no other signs of a severe injury, blood blisters can usually be treated at home.

See the doctor if there is:
    persistent severe pain
    inability to use the injured part
    numbness or unexplained weakness

Blood blister caused by pinching the thumb between the chain and the cassette teeth while working on the bike.
Blood blister caused by pinching the thumb between the chain and the cassette teeth while working on the bike.
Immediate care:
Leave the blister alone. Elevate the injured area. Apply a cold pack. When pain subsides, apply padding or a splint to protect the injured area.

Ongoing care:
Keep the wound clean, dry, and protected from chafing and bumping. Change the dressing every day, or whenever it accidentally gets dirty. After two days, you can resume washing (but always put a dry bandage on afterwards). When the wound looks like normal skin and feels like normal skin you can stop bandaging. Expect about 7 to 14 days for healing. The old skin can be snipped
off when you're sure the area is healed.

Watch for:
See the doctor if there is redness around the wound, red streaks, swelling, drainage, fever, tender bumps in the groin or armpit upsteam from the wound, or an unexplained increase in pain or tenderness.  See section on infection.