According to the FDA, there are no Federal standards or definitions associated with the term "Hypoallergenic". Normally manufacturers and companies use the term to claim their product has fewer ingredients that have been found to cause allergenic reactions in them than the regular version.At one point the FDA required companies to prove their claims of being "Hypoallergenic" but that was struck down by the court system back in 2000 because makeup companies fought back.
Since the term "Hypoallergenic" has no legal teeth, manufacturers can use it as a marketing ploy because the term suggests that the products are not as likely to cause allergenic reactions. At this point in time, most ingredients used in makeup are the same because the ones that caused issues have been removed. Furthermore, there are not enough studies to prove certain products cause fewer reactions.
Some companies run patch tests to see if their product causes reactions of any type but they use volunteers. Unfortunately, there is not guarantee the volunteer has allergies or sensitivities to certain ingredients which makes the patch tests not necessarily as accurate. This was especially true between 2000 and about 2010.
You may wonder how to tell if you can use something safely, especially since the term hypoallergenic is not regulated. Fortunately the FDA requires all products to list ingredients making it easier to determine if something you are allergic to has been used to formulate it. It is also possible to be allergic to almost anything so it is strongly recommended that if you have a history of multiple allergies, sensitive skin, or reacting to skin-care products, you should do spot test using the new product several days before using it over the face or body.
If you check the internet out you will find lists of recommended hypoallergenic brands. Some brands use formulations with fewer or limiting known ingredients that cause skin irritation while others rely on natural ingredients so they do not have parabens, chemical sunscreens, or mineral oils. In addition, many companies have started working with dermatologists to make sure the formulas are less likely to cause reactions and many are doing better testing.
Unfortunately, the bottom line is that no one brand is totally hypoallergenic. If you find yourself suddenly reacting to your makeup, you might want to be tested to see which ingredients you are allergic to so you can find one that works. Let me know what you think, I'd love to hear. Have a great day.