Complications

Minor burns are usually superficial and do not cause complications. However, deep second-degree and third-degree burns swell and take more time to heal. In addition, deeper burns can cause scar tissue to form. This scar tissue shrinks (contracts) as it heals. If the scarring occurs in a limb or digit, the resulting contracture may restrict movement of nearby joints.

Severe burns and some moderate burns can cause serious complications due to extensive fluid loss and tissue damage. These complications may take hours or days to develop. The deeper and more extensive the burn, the more severe are the problems it tends to cause. Young children and older adults tend to be more seriously affected by complications than other age groups. The following are some complications of some moderate and severe burns:

Dehydration eventually develops in people with widespread burns, because fluid seeps from the blood to the burned tissues and, if burns are deep and extensive enough, to the whole body.
Shock develops if dehydration is severe.
Chemical imbalances can result from extensive burns.
Destruction of muscle tissue (rhabdomyolysis) sometimes occurs with deep third-degree burns. The muscle tissue releases myoglobin, one of the muscle's proteins, into the blood. If present in high concentrations, myoglobin harms the kidneys.
Infection can complicate burn wounds. Sometimes the infection can spread throughout the bloodstream and cause severe illness or death.
Thick, crusty surfaces (eschars) are produced by deep third-degree burns. Eschars can become too tight, cutting off blood supply to healthy tissues or impairing breathing.