Can Smelling Peanuts Cause an Allergic Reaction?

Peanuts on a cutting board
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You can't react to peanuts just from the smell. But there's a reason this idea persists as a peanut allergy urban legend.

Peanut Allergy Involves Proteins

Your allergy to peanuts actually is an allergy to the specific proteins found in peanuts. These proteins are present in the peanuts themselves, and in foods made with the whole peanut. The proteins aren't present in purified peanut oil (which is fat, of course, not protein), and that's why most people who are allergic to peanuts can nonetheless consume peanut oil without getting a reaction.

Those specific allergenic peanut proteins also aren't present in the airborne flavor and aroma compounds that create the odor of peanuts. Yes, you inhale (and potentially ingest) these flavor and aroma compounds when you smell peanuts, but since they don't contain the problematic proteins, you won't react to them.

In fact, medical researchers have tested this: they exposed 30 peanut allergic subjects to peanut butter and a soy butter placebo for 10 minutes each at a range of one foot. Although the subjects could smell the peanut butter (and the soy butter, both of which were disguised by a combination of mint and tuna fish to keep participants from detecting which was which), none of them reacted to the peanut butter.

Many of these children had a history of prior contact-based or inhalation reactions to peanuts. The researchers concluded that "casual exposure to peanut butter" shouldn't cause problems in 90% of children who are highly sensitive to peanuts.

So Why Do Some People React?

It's really all about what you're actually inhaling.

As I said above, the chemical compounds that comprise what we think of as the "smell of peanuts" don't cause an allergic reaction. However, peanut dust and small airborne particles of peanuts most definitely can cause an allergic reaction in someone with peanut allergy.

If all you're smelling is peanut butter, it's unlikely any dust or small pieces of peanut are floating in the air — after all, peanut butter is sticky, not dusty.

But if people are shelling and eating peanuts in your vicinity, it definitely can spread peanut dust in the air. That means you could be smelling peanuts (which won't cause an allergic reaction by itself) and actually inhaling dust and peanut particles (which can cause a severe reaction).

In addition, when foods are cooked, they often release oils into the air — oils that can contain allergenic proteins and cause reactions. Finally, trace amounts of peanut products can get onto hands and be ingested by someone with an allergy, causing a reaction.

The Bottom Line

Just the smell of peanuts won't cause a reaction if you're allergic to peanuts. But the smell can warn you of the possible presence of actual peanut dust or oils in the air, and those can cause a potentially severe reaction. Tread with real caution if you're severely peanut allergic and you believe you smell peanuts.

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