Not in the usual sense of swallowing a toxin. Hickory tussock moth caterpillars (Lophocampa caryae) are covered in barbed hairs that can irritate skin on contact, especially in sensitive people, producing a localized itchy rash rather than a classic poisoning.
Penn State Extension notes that those hairs may irritate the skin of sensitive individuals, and that there are no known cases of systemic allergic reactions from this species’ hairs. Still, avoid handling the caterpillars or cocoons, and wash the area if hairs stick to your skin.
Source: Penn State Extension — Hickory Tussock Moth Caterpillar