I had an allergic reaction to a depillatory lotion. Feeling like I couldn't wash it off entirely because my skin was so inflamed and sensitive, and remembering how absorbent bentonite clay is, I applied a paste to my skin. It felt very soothing, and when I washed it off about 30 minutes later, all the pain and most of the inflammation was gone.
A friend of mine had an allergic reaction to tea tree oil applied to her skin, and bentonite clay was very soothing.
Bentonite clay should be helpful in exposure to poison ivy and other botanical (or synthetic) irritants, as it would absorb the oils that cause a prolonged reaction because they are difficult to wash off.
If using BC for irritated skin, I recommend making sure that your clay is well-hydrated before applying; it should be a soft texture, like yogurt or mayonnaise. Otherwise, the clay is very sticky when first mixed into water, and might be difficult and painful to apply (I always have a jar of hydrated BC on hand, because I have found it helpful for acid reflux).
Also, wash the clay off before it dries, or soak off gently in a tub, to prevent over-drying or having to pull on or scrub the skin.
I took sodium bentonite clay - 6 ounces per day for 3 days and a several week old problem of pain in stomach from low acid production went away very quickly, still using HCL betaine and enyzme tablets. Day 4, I can eat normally. It seems to have helped with candida as well and my energy levels are up and muscle pains vastly improved. I got a good quality one and it is better than other clays for internal use because of the ADSORB quality. Google absorbtion and adsorption for clay and you will get the technical explanation! I used it as a face mask - fantastic! Had a bath in, makes skin very smooth. Using it on hair next! Pam