Irritant (noun)

A substance or condition that causes irritation.

Origin:

From latin irritant-, present participle stem of irritare ("to provoke, excite").

Examples:

1. The dust was an irritant to her allergies.
2. The constant noise from the construction site was an irritant to her.
3. The strong scent of perfume was an irritant to his nose.
4. The rough fabric was an irritant to her skin.
5. The spicy food was an irritant to his stomach.