Blisters are due to the persistent or repeated rubbing against the skin. If a blister is small and closed, leave it alone. Protect it from further rubbing by applying a loose bandage. Try to avoid the activity or shoes that caused the blister.
If a small blister is on a weight bearing area, for example, bottom of foot, protect it with a moleskin pad and leave the area open.
If a blister is larger than 1 inch across, it is best to drain it, with a sterilized needle using rubbing alcohol. Puncture the blister at the edge and drain by gently pressing fluid towards the hole of the blister. Keep area clean, if the blister has torn open do not remove the flap of skin unless it’s dirty and torn or pus is forming. Try to smooth skin flap over the tender skin underneath. Change bandage once a day keep area clean and let it dry out at night.