4 Sneaky Skin-Irritating Ingredients

By this point, you probably don’t need a dermatologist warning you about retinoids’ potential to irritate your skin. That concern’s garnered ample attention on beauty blogs. But there are other, very common skin-irritating ingredients that are prone to eliciting reactions that will probably surprise you.

Propylene glycol

You may not be familiar with the name, but it’s an extremely common ingredient in various cosmetic formulations. The thing is, it’s not necessarily irritating by nature, like a retinoid. Rather, lots of people have an allergy to it. So many, in fact, that it was recently named the American Contact Dermatitis Society’s Allergen of the Year.

It’s favored by beauty brands because it’s incredibly versatile. Propylene glycol can function as a solvent, preservative, or humectant. It tends to be most problematic, though, in hair products, because it can cause irritation along the hairline and on the scalp.

Tea tree oil

Natural ingredients almost always receive a pass in conversations like these – after all, what damage can they do? But in the case of tea tree oil, the answer is, quite a bit, in the wrong combination of circumstances. 

For starters, it’s the most reported essential oil allergen. Often, sensitization, allergy, or dermatitis is caused by the use of pure oil. Products with high concentrations of tea tree oil are the most problematic for that reason. But aged or oxidized forms of the ingredients are also likely to cause a reaction because the tea tree oil components break down to other components that are even more likely to cause a skin reaction.

So, only use products whose packaging minimizes exposure to light and air. And if the color or scent seem a little off, discard the product.

Lavender oil

Lavender oil features in perfumes, skincare products, and household cleaners. In every instance, the oil contains a compound called linalool. When it reacts with oxygen, it forms sensitizing chemicals known as hydroperoxides. And when they come into contact with your skin, they can cause dermatitis.

Formaldehyde releasers

You can be an avid label-reader and still not have heard of formaldehyde releasers until now. That’s because they’re usually not listed, though they’re widely used as preservatives.

Instances of dermatitis resulting from formaldehyde releasers are quite low (though not non-existent). The greater concern is that if you’ve been using a product with a formaldehyde releaser for a while without any trouble, you can suddenly develop an allergy or reaction.

Toluene sulfonamide formaldehyde resin, in particular, should be avoided. It’s often found in nail polishes, and can cause redness and swelling, not just on or under the nail, but anywhere you touch your face.

It’s a good idea to keep a running list of the skincare products you’re using somewhere on your phone. Should you develop a sudden reaction without an obvious cause, those products will be one of the first things your dermatologist will ask about.