The best way to get rid of diaper rash is to use the same cream you use for athletes foot or jock itch. Diaper rash is a skin fungus. I haven't tried the spray, but the cream works great. A severe case of diaper rash can be cured in about five days using 1% tolnaftate cream after each diaper change. Powders can be used in addition for comfort, but are not necessary.
I use the Equate brand, which works fine. A 1/2 ounce tube costs about $2.50 at Walmart. Spread it thin, a little goes a long way. I have also found a larger size 4oz bottle of 1% tolnaftate online at:
http://www.americarx.com/index.asp?PageAction=VIEWPROD&ProdID=16446
The cream in the bottle is thinner but spreads much easier and costs $5.19.
The tolnaftate cream is also excellent for getting rid of bed sores if you're bed ridden, like I am at the moment.
Good hygiene includes changing bed sheets and pillow cases daily, changing diapers as needed. Even if you don't wet the diaper, change it after a few hours because the body's sweat causes dampness that leads to diaper rash and bed sores.
While I was at the hospital I developed diaper rash and bed sores, and they gave me an ineffective lotion to wipe over my body. The lotions may have anti-fungal properties, but they also keep the skin moist, which is what you want to avoid where there is no air circulation. The lotion I was given actually perpetuated the bed sores and diaper rash. I had to ask the nurse for tolnaftate cream by name, and she ordered it for me through the hospital's pharmacy. But be forwarned, the hospital charged me $20 for a 1/2oz tube. Bring your own tolnaftate cream to the hospital when you go in, or have a family member pick it up for you at the local Walmart.