It is apparently caused by an allergic reaction to the fungus. The scalp becomes swollen, mushy, and oozes a characteristic mixture of yellow fluid and pus, and there is considerable hair loss. The disease is much more common in patients of African-American descent.
Topical potions are of no help in treating a kerion.
About six weeks of treatment is usually needed. Because of concerns about possible toxicity from such long term therapy, your doctor may get some blood work and a urine test about four weeks into treatment to check the blood, urinary system and liver functions, but many pediatric dermatologists don't bother because the treatment is only six weeks and side effects are rare. Sometimes oral steroids are given for severe kerion because the sore may leave some permanent scarring, loss or discoloration of the hair.