Can Smelling Peanuts Cause an Allergic Reaction?

The smell of peanuts could indicate peanut dust in the air

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: If you smell peanuts (or peanut butter), it usually means peanuts or peanut-based products are in your vicinity, and that means you might be at risk for a reaction from peanut dust.

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. The smell (or odor) of peanuts is contained in smaller organic compounds that are not peanut protein.

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. That's not 100%, of course, so you still should be careful.

Why Do Some People React?

Reactions that appear to involve the smell of peanuts in the air are 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 contain peanut protein and therefore 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. One exception to this rule is if you're smelling peanut butter near a nut butter grinder; it's not uncommon for upscale grocery stores and health food stores to offer fresh-ground peanut butter, almond butter, and occasionally other types of nut butters. These machines are a real potential risk and you should stay away.

Similarly, 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), but also actually inhaling dust and peanut particles (which can cause a severe reaction). This is an issue at stadiums that serve peanuts and in some stores and restaurants that offer free unshelled peanuts for customers to snack on.

In addition, when foods are cooked, they often release oils into the air—oils that can contain allergenic proteins and cause reactions. Boiled peanuts, or certain types of Asian foods that include peanuts and peanut sauce, could pose this risk.

Finally, trace amounts of peanut products can get onto hands and be ingested by someone with an allergy, causing a reaction, even if there's no peanut dust in the air. So if you smell peanuts, you should be careful to wash your hands before eating or moving your hands near your mouth.

A Word from Verywell

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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