I don't have PPD allergy, but I do have rosacea and pretty significant skin allergies. I was allergic to CK, anything Bioterra, original Shea M li to name a few. Very common chemical allergy in products is propylene glycol.

My hair prefers the more natural products from the online, boutique type companies. I stay away from a lot of chemicals, especially polyquats.
3a (Corkicelli), highlighted, fine, low porosity
SE PA

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me, Aloe Fix