Leg blisters can be caused by many factors. They can result from physical damage to the skin from the sun, burns or repeated friction resulting from rubbing against something. Chemical imbalances or diseases in the body, such as diabetes or poor blood circulation, can cause blisters to appear on the legs. Environmental factors such as bacteria or fungal infections also can lead to the development of leg blisters. Depending on the cause of the blisters, the treatments can range from simply waiting for them to heal to draining and bandaging them.
A blister is a collection of fluid — sometimes lymph fluid — that develops between the top two layers of the skin, called the epidermis, and the dermis. It can be formed by the body as a defensive measure to prevent repeated rubbing from further damaging the skin. The fluid inside can sometimes be blood, in which case it's called a blood blister; this is a result of damaged blood vessels, usually caused by physical trauma. One of the complications that can occur with blisters is infection, in which case professional medical attention needs to be sought.
One common cause of leg blisters is a condition known as eczema. The exact causes of eczema are unknown, but it begins as a rash that can eventually become inflamed and cause blisters. Eczema is not a condition that is dangerous, but it can be very persistent and affect the appearance of the person who has it.
A much broader cause for leg blisters is known as dermatitis. This is not a single disease but an umbrella term referring to various conditions that cause lesions or irregularities on the surface of the skin. Many of these conditions can develop into blisters. The causes for many types of dermatitis are not fully understood but might be attributable to an overactive immune system response.
Poor blood circulation from a condition such as diabetes is another common cause for leg blisters. The blisters may form because the skin in the area does not receive the correct amount of nutrients and support because an insufficient amount of blood is directed to the skin. Certain medications can help to reduce the amount and duration of such blisters, but they could remain as long as circulation is an issue.
Physical damage to the skin can cause the formation of leg blisters, as well. This can be caused by sun damage, as in severe sunburn, or as a result of contact with a hot surface. Friction also is known to cause blisters, such as when boots or shoes rub against the skin until a protective blister appears. These blisters tend to dissipate fairly quickly.