As other medical methods casts could have negative side effects. These are injuries by virtue of increased pressure, thrombosis or a permanent immobility of joints. If one of these effects occurs the cast has to be removed immediately.

Injuries by virtue of increased pressure
An increased pressure inside a cast is caused by swellings. Consequences are a bad circulation and a disturbed sensitivity, furthermore irreversible injuries of tissue, nerves and muscles. The patient notices a growth of pains, a tingling feeling or the sense of tired limbs. The colour of fingers and toes respectively turns into blue or white, and finally one is unable to move them.

Particularly after accident or surgery swellings could occur which cause pressure. As prevention the cast should be splitted on one side and an elastic bandage be wrapped round. Already during the application compression and congestions are avoidable by an adequate padding, especially where bones are located immediately under the skin. Further, bandages should not be wrapped too tight.

Thrombosis
Blood clots could cause congestions in vessels, this is called thrombosis. In a cast the risk is elevated by the immobility and the reduced speed of blood flow. Vascular injuries and an increased inclination of coagulation after accident or surgery support thrombosis, too. If the clots are transported to the lung a life-threatening embolism could occur. Symptoms of thrombosis are growing pains in the casted limbs and swellings of fingers or toes.

To support the blood flow back to heart and to prevent swellings, immobilized extremities should be placed on cushions or in slings, fingers or toes should be moved often.

An existing vein disease, overweight and hormones for birth control raise the risk of thrombosis. If in these cases a cast is unavoidable coagulation should be pharmacologic decreased.

Permanent immobility of joints
If injured joints rest for a long period in a cast a permanent immobility could occur, because the surfaces of the joints plaster over. Therefore only joints which must be immobilized should stay in a cast and remain as short as possible. When the cast is removed physiotherapy should follow.