Nut allergies affect about 2% of the Canadian population and can be broken down into tree nut allergies (like almonds or cashews) and peanut allergies (peanuts aren’t actually nuts but legumes). These allergies are caused by ingesting or inhaling certain allergenic nut proteins, not all of which have been identified yet. So, if these proteins were present in oils made from nuts that are used in cosmetics like hand cream or shampoo, one could have a reaction to them.
If you’re allergic to peanuts, that’s likely all you’re allergic to. Numbers vary on the percentage of people allergic to peanuts that have cross-reactivity to other legumes like soy or tree nuts, but it’s not a majority. On the other hand, if you’re allergic to one kind of tree nut, chances are you’re allergic to several. You are likely, however, not allergic to coconut or nutmeg (though it’s a common misconception) as they are not nuts.
Studies have found that contact allergic reactions can occur due to exposure to allergens in cosmetics. But these reactions only occur if the relevant proteins are intact, so in general, the more processed and refined the cosmetic, the smaller the likelihood of a reaction.
Allergens in cosmetics can pop up more than you might expect. Peanut oil is often used under the name arachis hypogaea in shampoos and creams. Tree nut oils in cosmetics are downright common, with almond oil, argan oil and shea butter being some common examples. Coconut oil is also growing in popularity lately, with many companies incorporating it into products in order to market them as ‘natural’. Looking in my bathroom I found six products containing peanut, tree nut or coconut oils.
Since every allergy is different it’s really best to evaluate your own situation. If you’re allergic to tree nuts but not coconut, look for coconut-based products. If you’re allergic to tree nuts and coconut, you might have to look for specialty products or make your own. Or, you might check the products you’ve already been using and realize that they contained your allergen, in which case you’re probably good to keep on using them.