What causes AK?

AK results from damage to the skin due to exposure to the sun over a long period of time. Sun damage to the skin is more of a risk in people with fair skin and blonde or red hair, but people with darker skin can also develop AKs if they spend a long time in the sun without protection. Individuals with immune systems that are weakened as a result of chemotherapy, AIDS, or use of drugs that suppress the immune system following an organ transplant also have a higher risk of developing AK when exposed to the sun.