A lot of the cosmetic ingredients that we use in our daily life can cause adverse reactions such as allergies. You have leave-on and rinse-off products. The longer you leave a certain product on your face, the more probably a product that contains allergens can cause a reaction such as redness, swelling and rashes for example (this is not always the case, some people are more sensitive than others). Using ingredients that are known to give reactions on an inflammed area is not (never) a very good idea, because it can only enhance the effect of an allergic reaction. A few years ago I tried a perfume (on my b-day) and I had rashes all over my chin and neck. I was always curious about what caused it, but I have a good idea that I figured that out ;).
If you have sensitive skin and have troubles with some skin care or other beauty products, you should keep a good eye on the ingredient label and should avoid these products:
Fragrances are everywhere, you can find them in perfume (contains up to 60 procent in perfume extract), in toiletries that contain parfum and in other cosmetics. A fragrance can be natural or synthetic but they can both cause allergic reactions. It is always wise to try a new perfume on a little spot on your neck before you spray it all over your body (that's what I do since the rash incident).
Since there are up to 3000 different fragrances, only a few of them will be mentioned here.
Oak moss and isoeugenol are the most allergenic. Other fragrances that more often cause allergic reactions are cinnamic aldehyde, cinnamic alcohol, eugenol, hydroxycitronellal (Nivea creme contains this ingredient), geraniol and amyl cinnamaldehyde.
Balsam of Peru is also a fragrance that is known to cause a lot of allergic reactions. It is used in food, perfumes, toiletries etc,... The balsam is also known as Black balsam and has many other names. It contains a lot of different substances such as: cinnamic aldehyde, cinnamic cinnamon, cinnamon benzoate, benzyl benzoate, vanillin, vanillic acid,... It can cause redness, swelling, itching and can give blisters.
Preservatives are used in toiletries to prevent bacteria from growing (see a full blogpost on parabens here).
Thiomersal also known as merthiolate, thimerosal or vitaseptol is a preservative that can be found in eye shadows and mascara for example. It can cause swelling and redness of the eyelids and normally resolves after a few days.
Formalin and Formaldehyde both have an unpleasant smell but are normally neutralized with a perfume so normally you won't notice the smell. It can cause dermatitis, so inflammation of the skin.
Parabens are used a lot in the cosmetic industry. The three esters that are most used are methyl-, ethyl- and propylparaben. They are found the most in leave-on and rinse-off products. They are weak allergens, so not much to worry about.
Paraphenylenediamine (PPD) is used in hair dyes, color shampoos, make up and many other products. Symptomes such as inflammation of the eyelids/ears and redness of the scalp. It can be found in artificial henna.
These were the most common allergens in the beauty industry. Most people don't have any problem with these ingredients but if you have sensitive skin and/or experience rashes/redness/... and you think your beauty routine has something to do with it, then I hope you found this helpful ;)!
Talk to you soon,