Blisters are smaller or larger vesicles filled with fluid located in upper layers of skin. Usually blisters occur as a defensive response to physical damage, but they can emerge as a sign of some diseases. Blister usually contains sterile liquid, but its content may get secondary infected.



Pressure force is probably the most common causes of blistering, typically because of tight shoes or because of exhausting walk.


Blisters occur as a response to heat damage and their formation usually indicates presence of at least second degree burns.


It is the same case like burns. Frostbite damages tissues and blisters act as defense reaction.

Chemical damage

Skin reacts by blistering in contact with a number of aggressive chemicals, it was typical for so-called blistering agents (e.g. mustard gas) used as chemical weapons in the First World War.


This skin condition is caused by bacteria from groups of streptococci or staphylococci. Skin is affected by reddish lesions with pus-filled blisters. Bacterial infection may occur primarily or secondary to a viral infection.

Bullous erysipelas

This infectious condition is a severe form of erysipelas. It is an infectious disease typically caused by streptococci. Both skin and deeper tissues are affected; typical location of occurrence is lower extremity. High fever is usually present, infected skin is reddish and painful and affected limb is swollen. Blisters are filled with yellowish fluid or even blood. This condition may lead to fatal sepsis without adequate therapy.

Herpes simplex

Herpes simplex is a result of infection caused by herpes simplex viruses. It may occur at different locations of the body, but typically on the lip. Blisters are painful and they can be secondary infected by bacteria (impetiginization).


Chickenpox is a viral infectious disease caused by varicella zoster virus. The disease starts as a rash classically associated with febrile illness. Small and very itchy pimples occur on the skin. These pimples often evolve into little blisters filled with clear fluid or pus. They are typically located on the face and chest. Rash and vesicles can appear even in hair and in mouth.


It is also caused by varicella zoster virus. After chickenpox ends, the virus doesn’t disappear from our body, but it hides within nerve ganglia near the spinal column. During situations when organism is weakened virus activates and spreads through nerve fibers to a certain skin area causing shingles. Disease manifests with painful skin rash and vesicles. Virus attacks only part of skin that is innervated by nerve along which the virus spreads. Shingles head affection is particularly dangerous because it can cause permanent eye disorders.

Allergic reactions

Blisters may arise as part of a local skin reaction to an allergen (contact dermatitis) or as a part of general allergic condition known as anaphylactic shock.


Pemphigus is a term used for a whole group of skin diseases having an autoimmune cause leading to skin damage with blisters formation. The best known example of these diseases is Pemphigus vulgaris.


Blisters are formed in response to skin damage and therefore it is not suitable to puncture them. It is recommended to prevent further skin irritation and blistering distortion. Hygiene measures are needed to prevent penetration of microorganisms into the blister fluid. Blisters heal themselves gradually. If blisters result of some infection or other disease, then we treat the underlying cause (of course, only when possible).

Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources