Allergies happen when the immune system reacts to a normally harmless substance as if it were dangerous. These substances are called allergens, and common examples include pollen, dust mites, pet dander, mold, insect stings, and certain foods. Allergies matter because they can affect breathing, skin, digestion, sleep, and school activities.
Most allergic reactions are mild, but some can be serious and need quick medical help.
Key Facts
- An allergen is a substance that can trigger an allergic reaction in some people.
- Common allergy triggers include pollen, dust mites, mold, pet dander, insect stings, and foods such as peanuts, eggs, milk, or shellfish.
- In many allergies, the immune system makes IgE antibodies that recognize a specific allergen.
- Mast cells can release histamine, which causes symptoms such as sneezing, itching, swelling, watery eyes, and a runny nose.
- Allergy symptoms can affect the nose, lungs, skin, eyes, or digestive system depending on the allergen and the person.
- Reducing exposure, following a care plan, using medicines correctly, and carrying emergency medicine when prescribed can help manage allergies.
Vocabulary
- Allergy
- An allergy is an immune system reaction to a substance that is usually harmless to most people.
- Allergen
- An allergen is a substance such as pollen, dust, food, or pet dander that can trigger an allergic reaction.
- Immune system
- The immune system is the body's defense network that helps identify and respond to germs and other foreign substances.
- Histamine
- Histamine is a chemical released by immune cells that can cause allergy symptoms such as itching, swelling, sneezing, and mucus production.
- Anaphylaxis
- Anaphylaxis is a severe allergic reaction that can affect breathing or blood pressure and requires emergency medical care.
Common Mistakes to Avoid
- Thinking allergies are the same as colds is wrong because colds are caused by viruses, while allergies are immune reactions to allergens.
- Ignoring breathing trouble during an allergic reaction is dangerous because wheezing, throat tightness, or trouble breathing can be signs of a serious reaction.
- Assuming natural or tiny amounts of an allergen are always safe is wrong because some people can react to very small exposures.
- Sharing allergy medicine without medical guidance is unsafe because the correct medicine and dose depend on the person, symptoms, and doctor's instructions.
Practice Questions
- 1 A student tracks pollen levels for 5 days: 30, 45, 60, 40, and 75 grains per cubic meter. What is the average pollen level for the 5 days?
- 2 A classroom has 24 students. If 1 out of every 6 students has a seasonal allergy, how many students in the classroom would you expect to have a seasonal allergy?
- 3 A student sneezes and has itchy eyes every spring but does not have a fever. Explain why this pattern fits allergies more than a cold.