How could they? - The pheros sold here are chemically identical to the ones produced naturally on your skin.
If Pheros were going to harm you, you would have known about it longsince. At the very latest by the time you hit puberty when your natural production tends to soar! The only one with any small potential for harm sold here is the non-human experimone Meo-Est, which IIRC is not used in any consumer-line product - Its issues are already well discussed if you search
There is however a small potential for irritation/allergy issues from the solvent/scent components and the severity would be highly variable between affected individuals - although AD is one of the better companies for low-ittitation IME but personally I get a minor reactio from standard Ammo’s FF21 scent. All the others I’ve tried so far are fully usable though.
BTW if any staffers are reading this - We need a sticky for this subject alone!
Some natural or manmade fragrance components in any pheromone product can cause a rash or contact dermatitis.
For instance, Cheer Free laundry detergent is made free of all fragrance for a small number of people who are allergic or fragrance sensitive. A true allergy needs a medical diagnosis.
In the case of ours or any mone product, contact the vendor customer service for exchange if you have an issue. Rarely does anyone have severe allergy to consumer products, even retail soaps and toiletries.
If anything is gonna harm your skin, its gonna be the cheap colognes out there that are jammed with different synthetic chemicals. The stuff on Androtics Direct seem to be well researched and high-quality, so i doubt they would have any harmful effect on your skin.