Hydrocortisone is a steroid medication that treats inflammation in the body. The drug comes in an oral form to take by mouth, and a topical form to apply to the skin.
Some kids ask to be left alone as early as 5 or 6; others enjoy having your company until they start approaching puberty, closer to 9 or 10. Bathing alone, however, can be risky because of drowning dangers, and it can take just a few seconds for even older kids to slip and drown in only a few inches of water.
I think that a 6 year old can bathe alone if an adult is within hearing distance. I know of a horror story where an 8 year old had his/her 1st seizure in the bathtub, was alone (parent was elsewhere in house), slipped under the water, and... When my nine-year-old daughter is bathing, I am within earshot of her.