Causes of blisters

Blisters are most often caused by skin beingdamaged by friction or heat. Certain medical conditions also cause blisters to appear.

The damaged upper layer of skin (epidermis) tears awayfrom the layers beneath and fluid (serum)collects in the space to create a blister.

Friction

Friction blisters are common in people who are very active, such as sports players and thosein the military. They're usually caused by poor-fitting shoes.

A blister can develop if the skin is rubbed for a long period or if there's intense rubbing over shorter periods.

Friction blisters often occur on the feet andhands, which can rub against shoes and handheld equipment, such as tools or sports equipment. Blisters also form more easily on moist skin and are more likely to occur in warm conditions.

Skin reaction

Blisters can appear when skin is exposed to excessive heat for example, when you have Sunburn .

Blisters can sometimes form when your skin comes into contact with substances such as cosmetics, detergents and solvents.

Read about burns and scalds .

They can also develop as an allergic reaction to an insect bite or sting .

Medical conditions

Anumber of medical conditions may cause blisters. The most common are:

• chickenpox a childhood illness that causes itchy red spots
• cold sores small blisters that develop on the lips or around the mouth, caused by a virus
• herpes a sexually transmitted infection (STI) that most commonly affects the groin
• impetigo a contagious bacterial skin infection
• pompholyx a type of eczema
• scabies a skin condition, caused by tiny mites, which may lead to blisters developing on young children's feet or palms of their hands
• hand, foot and mouth disease a viral infection that usually affects young children

Severalrarer conditions can also cause blisters. They are:

• bullous pemphigoid a skin disease that causes large blisters and usually affects people over 60 years of age
• pemphigus vulgaris a serious skin condition where blisters develop if pressure is applied to the skin; the blisters burst easily, leaving raw areas that can become infected
• dermatitis herpetiformis a skin condition that causes intensely itchy blisters, usually on the elbows, knees, back and buttocks; blisters usually develop in patches of the same shape and size on both sides of the body
• epidermolysis bullosa a group of rare inherited skin disorders that cause the skin to become very fragile; any trauma or friction to the skin can cause painful blisters
• chronic bullous dermatosis of childhood a condition that causes clusters of blisters to develop on the face, mouth or genitals
• bullous ichthyosiform erythroderma a type of icthyosis someone is born with, which causes inflamed, scaly skin with blisters