The chemical which cause allergy is called _______

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the name of the chemical that causes allergies.

2. **Identifying the Chemical**: In the human body, when an allergic reaction occurs, a specific chemical is released. This chemical is known for its role in the allergic response.

3. **Recognizing the Role of Histamine**: The chemical that is primarily responsible for causing allergy symptoms is histamine. Histamine is released by the immune system during an allergic reaction.

4. **Functions of Histamine**: Histamine acts as a vasodilator, which means it helps to widen blood vessels. It also has other effects, such as contracting the smooth muscles of the bronchi (airways) and relaxing other muscles.

5. **Conclusion**: Therefore, the chemical that causes allergies is called **histamine**.

**Final Answer**: The chemical which causes allergy is called **histamine**.

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