How can you tell if a blister in your foot is infected?

It's appearance: An infected blister will have some associated redness around the blister, warmth and there may be some drainage which may look like pus. If you are unsure, have it checked by your doctor.

SImple means: You need to identify why the blister developed and eliminate that problem. Then, the keys are to cover and protect the injured area with dressing changes every other day to allow healing. Remember that inflammation (red, hot, swollen and tender) are important parts of healing and do not necessarily mean infection. If the wound is healing, it cannot be infected. If it gets worse, see a doctor.

Signs/Symptoms: A blister that is infected typically will have some drainage that is purulant (pus-like) and will be associated with erythema (redness and heat). The redness may be on the blister as well as the surrounding skin. Swelling is present, and it tends to be sensitive to touch. If in doubt, have your doctor check it!