Function

• As Efudex breaks down on your skin, it interferes with the process used to make DNA and RNA that are necessary for cells to divide. Because cell division is the mechanism that cancer uses to grow, this makes Efudex effective at treating skin cancers.
  
  

Uses

• In some cases, doctors prescribe Efudex to treat solar keratoses, areas of the skin that are damaged by the sun and at risk for developing into skin cancer. The cream is also used to treat basal cell carcinomas, a type of skin cancer.
  
  

Significance

• In the treatment of basal cell carcinoma, Efudex destroys 93 percent of cancers, according to RxList. For this reason, doctors prefer to use surgical removal of tumors when possible, as this method is 100 percent effective.
  
  

Risks

• The most common side effects of Efudex is burning when you apply the cream, increased sensitivity to the sun, itching, oozing, skin rashes and skin tenderness or soreness, according to the Mayo Clinic. Risks of Efudex include decreased amounts of white blood cells and inflammation of the stomach, pancreas or bowels.
  
  

Considerations

• Because Efudex has been linked to birth defects, avoid using the cream during pregnancy. If you have a history of dihydropyrimidine dehydrogenase enzyme deficiency--or are taking tamoxifen, warfarin or tinidazole--it may not be safe for you to use Efudex.