Despite affecting some 50 million Americans, allergies aren’t super well understood. The sparks that ignite your immune system can range from sunlight to onions, and symptoms of an attack are just as varied. For that reason, we’re spending several weeks writing about allergies—what they are, how they manifest, and how we can find relief. This is PopSci’sAllergic Reaction.

Allergies are unpleasant. Just ask anyone who equates the advent of spring with a runny nose or the presence of a cute puppy with itchy eyes. Unfortunately, most allergy treatments—which tend to involve lots and lots of needles—are as unpleasant as the allergens themselves.

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