Which of the following chemicals are responsible for causing allergic responses such as sneezing, watery eyes, running nose, pain, and heat at the site of infection?

Histamine and serotonin

Histamine and serotonin are the chemicals responsible for causing allergic responses such as sneezing, watery eyes, running nose, pain, and heat at the site of infection.

When an allergen triggers an allergic reaction in the body, mast cells and basophils release histamine and serotonin as part of the immune response.

These chemicals cause blood vessels to dilate, smooth muscle contraction, and increased mucus production, leading to the characteristic symptoms of an allergic response.

Histamine and serotonin play crucial roles in the inflammatory process associated with allergies.