What are blisters?

Blisters (doctors like to call them vesicles and bullae) are bumps on the skin that are filled with fluid produced by skin (serum-, pus-, or blood-filled).

What causes blisters (vesicles and bullae)?

 Most common causes are friction blisters, burns, infections (impetigo, herpes), allergic reactions and autoimmune diseases (diseases where your own immunity attacks your skin such as lupus, pemphigoid and pemphigus among others).

When should I see my health care provider?

It is always wise to see your health care provider for an initial exam and for a correct diagnosis. But for sure you should see your health care provider: if the blister or blisters are near your eye, if there are numerous blisters and if they are spreading, if the blisters are painful, if blisters do not heal in about a week, or if you are simply not sure what could be the cause.

How can I treat a blister?

Try not to pop or poke your blister, since the blister is the best dressing for the underlying sore, plus you may infect it. Also it is best to leave it as is, so that your health care provider can have a better idea about its cause when she or he examines it. If the blister pops or breaks open spontaneously, keep the area clean and gently cover it with a bandage to protect it.

How can my health care provider help me?

Your health care provider will examine your blisters and get the story about your blisters from you. In the vast majority of cases, that would be enough to come to the correct diagnosis and treatment. However, sometimes your health care provider may need to refer you to a dermatologist and/or do some additional tests including doing biopsy (sampling) of the skin. A skin biopsy is a cutting a small sample of the changing skin off to be looked under microscope. There are two types of biopsies, both performed under the local anesthesia and both taking about 5-10 minutes to perform – a shave biopsy and a punch biopsy.

Shave biopsy is the most common type since it is usually preferred both by patients and by their health care providers, since it does not require placement of stitches and is faster. Your health care provider will numb the skin with small amount of fast acting local anesthetic and then use a razor blade or a more sophisticated instrument called a Dermablade (our favorite), which is actually a razor blade with handles that enable your healthcare provider to have a better control over the depth of the biopsy. Afterwards, the bleeding is stopped by using special liquid called aluminum chloride (which is, by the way, the active ingredient in many anti-sweating deodorants). Then plain Vaseline or a double antibiotic ointment and bandage are placed on the biopsy wound.

A person is getting their arm shaved by another person.
Shave biopsy


Punch biopsy is also a very fast procedure, where your health care provider will numb the skin with small amount of fast acting local anesthetic and then sterilize the skin using special cleansing swabs soaked with povidone-iodine, or chlorhexidine gluconate, put sterile drape over the area, and then use a pen-like cylindrical instrument called a punch, which looks like a very small cookie-cutter that would produce small cylindrical specimen with diameter of about 4 mm and depth of about 5-8 mm. We usually close the wound and stop the bleeding by placing a nylon stitch that should be removed in 1-2 weeks. Then plain Vaseline or a double antibiotic ointment and bandage are placed on the biopsy wound. The results of the skin biopsy are usually available within 1-2 weeks. We always call our patients with all the results. Please, never agree to a policy of “no news is good newsâ€, since results may be misplaced with possible bad outcome to your health.

For more specific questions on blisters (vesicles and bullae) please send us your question using our blog below.

  • Hi,
    I was recently diagnosed with Herpes Simplex 2.
    I got the odd blister in my genital area but also a medium one on my upper abdomen which I didn’t link it to as I got the diagnosis later.

    Is that due to Herpes… Or could it be syphillis!!!?

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