Common Triggers of Allergic Reactions Practice Questions

25 multiple-choice questions on Common triggers of allergic reactions for paramedic and EMT students, from Chapter 26 (Immunologic Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. The most common cause of anaphylaxis in children is:

   1. A. Insect stings
   2. B. Latex
   3. C. Contrast dye
   4. D. Food
   Show answer

   Answer: D. Food

   Peanuts, tree nuts, milk, eggs, and shellfish are common triggers.

2. Deaths from food anaphylaxis occur most often in which age group?

   1. A. Infants under 1 year old
   2. B. Toddlers in day care
   3. C. Teens and young adults
   4. D. Adults over age 80
   Show answer

   Answer: C. Teens and young adults

   Fatal food anaphylaxis peaks in adolescence and young adulthood. Risk-taking with foods, not carrying an auto-injector, delayed epinephrine, alcohol, and poorly controlled asthma all contribute. Infants and toddlers often react to foods but rarely die from it.

3. Which insects most often cause anaphylaxis?

   1. A. Hymenoptera
   2. B. Mosquitoes and gnats
   3. C. Ticks
   4. D. Spiders
   Show answer

   Answer: A. Hymenoptera

   The order Hymenoptera includes bees, wasps, hornets, yellow jackets, and fire ants.

4. A honeybee differs from a wasp because a honeybee:

   1. A. Can sting many times over
   2. B. Rarely causes any allergy
   3. C. Leaves its stinger behind
   4. D. Has no venom
   Show answer

   Answer: C. Leaves its stinger behind

   The barbed stinger detaches with the venom sac. Wasps can sting multiple times.

5. Fire ant stings typically cause:

   1. A. Bull's-eye rashes
   2. B. Sterile pustules
   3. C. Black necrotic ulcers
   4. D. Paralysis
   Show answer

   Answer: B. Sterile pustules

   Fire ants bite and sting repeatedly, leaving pustules that should not be opened.

6. Peanut allergy is significant because:

   1. A. It often causes severe, lifelong reactions
   2. B. It usually resolves in early childhood
   3. C. It causes skin rash but not anaphylaxis
   4. D. It needs a large amount of peanut to trigger
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   Answer: A. It often causes severe, lifelong reactions

   Even trace amounts can cause anaphylaxis.

7. Patients with shellfish allergy were once told to avoid contrast dye because of iodine. Current evidence shows:

   1. A. A very high contrast risk
   2. B. A need for steroid premedication
   3. C. Iodine itself is the allergen
   4. D. No special contrast risk
   Show answer

   Answer: D. No special contrast risk

   Contrast reactions are not related to iodine in shellfish. Shellfish allergy is caused by muscle proteins such as tropomyosin, not iodine, so routine steroid premedication is not needed for these patients.

8. A man who had several tick bites this summer wakes at 2 a.m. with hives and lightheadedness, about 5 hours after a steak dinner. You should suspect:

   1. A. Food poisoning from the steak
   2. B. Alpha-gal (red meat) allergy
   3. C. Lyme disease from the tick bites
   4. D. A vasovagal faint from fatigue
   Show answer

   Answer: B. Alpha-gal (red meat) allergy

   Lone star tick bites can sensitize people to alpha-gal, a sugar in mammalian meat. Unlike most food allergies, reactions start 2 to 6 hours after eating beef, pork, or lamb, often at night, and can be anaphylaxis. Hives and lightheadedness are not features of food poisoning or Lyme disease.

9. Patients with latex allergy may also react to:

   1. A. Rice, potatoes, and oats
   2. B. Milk, eggs, and cheese
   3. C. Bananas, avocados, kiwi
   4. D. Wheat, corn, and barley
   Show answer

   Answer: C. Bananas, avocados, kiwi

   This latex-fruit syndrome is due to similar proteins.

10. When caring for a latex-allergic patient, you should:

    1. A. Use latex-free equipment
    2. B. Use powder-free latex gloves
    3. C. Give diphenhydramine before contact
    4. D. Give prophylactic epinephrine
    Show answer

    Answer: A. Use latex-free equipment

    Check equipment such as BP cuffs, tourniquets, and IV tubing. Powder-free latex gloves still contain latex proteins. Premedication does not make latex exposure safe and is not a substitute for latex-free equipment.

11. Aspirin and NSAIDs can trigger reactions in some patients with:

    1. A. Chronic hypertension
    2. B. A known penicillin allergy
    3. C. A known sulfa drug allergy
    4. D. Asthma and nasal polyps
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    Answer: D. Asthma and nasal polyps

    Aspirin-exacerbated respiratory disease causes bronchospasm after NSAID use. Hypertension and allergies to penicillin or sulfa drugs do not predict NSAID-triggered bronchospasm.

12. A latex-allergic nurse develops wheezing and itchy eyes in a room where coworkers are putting on powdered latex gloves. She never touched the gloves. The likely route is:

    1. A. Anxiety about a possible latex exposure
    2. B. Latex proteins on airborne glove powder
    3. C. Coincidental seasonal pollen allergy
    4. D. Contact with latex in her own shoes
    Show answer

    Answer: B. Latex proteins on airborne glove powder

    Cornstarch powder in latex gloves absorbs latex proteins and carries them into the air when gloves are put on or snapped off, so sensitized people can react by inhaling them. This is why the FDA banned powdered medical gloves in 2016. Everyone near a latex-allergic patient should use latex-free gloves.

13. Penicillin-allergic patients may cross-react with:

    1. A. Macrolides like azithromycin
    2. B. Sulfa drugs
    3. C. Fluoroquinolones
    4. D. Some cephalosporins
    Show answer

    Answer: D. Some cephalosporins

    Cross-reactivity is lower than once thought but still possible. Macrolides, sulfa drugs, and fluoroquinolones are not beta-lactams, so they do not share penicillin's ring structure.

14. About 1 in 10 patients reports a penicillin allergy. When these patients are formally tested, most of them:

    1. A. Are not truly allergic
    2. B. Have a severe IgE allergy
    3. C. React to every antibiotic
    4. D. Are also allergic to latex
    Show answer

    Answer: A. Are not truly allergic

    About 10% of patients carry a penicillin allergy label, but fewer than 1% of the population is truly allergic. Many labels come from childhood rashes, side effects, or allergy that faded over time. Record the actual reaction in the history, since an inaccurate label can lead to less effective antibiotics.

15. Which food allergy is most common in adults?

    1. A. Cow's milk
    2. B. Hen's eggs
    3. C. Shellfish
    4. D. Soy
    Show answer

    Answer: C. Shellfish

    Shellfish allergy often begins in adulthood and tends to persist.

16. Contrast media reactions are usually:

    1. A. Type IV delayed
    2. B. Anaphylactoid
    3. C. Autoimmune
    4. D. Infectious
    Show answer

    Answer: B. Anaphylactoid

    They result from direct mast cell activation rather than IgE.

17. A patient stung multiple times by bees has vomiting, headache, and muscle breakdown but no hives. This may be:

    1. A. Classic anaphylaxis
    2. B. A local reaction
    3. C. An infection
    4. D. Venom toxicity
    Show answer

    Answer: D. Venom toxicity

    Massive envenomation can cause toxic effects even without an allergic reaction.

18. Which of the following is a common nonfood, nondrug cause of anaphylaxis?

    1. A. Cold-induced urticaria
    2. B. Exercise alone
    3. C. Insect stings
    4. D. Pollen inhalation
    Show answer

    Answer: C. Insect stings

    Hymenoptera stings are a leading cause in adults.

19. A swarm of bees is attacking a man near a hive. The best initial action is to:

    1. A. Get him away from the swarm
    2. B. Scrape out stingers on scene
    3. C. Have him jump into a pool
    4. D. Have him lie still and calm
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    Answer: A. Get him away from the swarm

    With many stings, the first step is to get the patient (and yourself, with protective gear) away from the swarm, since bees can pursue for hundreds of meters. Bees wait over water, and lying still allows more stings. Remove stingers once you are clear.

20. Allergens that commonly cause seasonal allergic rhinitis include:

    1. A. Penicillin and sulfa
    2. B. Peanuts and shellfish
    3. C. Latex and contrast
    4. D. Pollen and mold
    Show answer

    Answer: D. Pollen and mold

    Hay fever causes sneezing and congestion but rarely anaphylaxis.

21. Why should patients with known allergies wear medical alert jewelry?

    1. A. It lets crews skip taking a full history
    2. B. It informs care when they cannot speak
    3. C. It replaces carrying an auto-injector
    4. D. It prevents reactions to the allergen
    Show answer

    Answer: B. It informs care when they cannot speak

    It helps EMS avoid triggering a reaction and identifies the cause. It does not replace a history, it is no substitute for carrying epinephrine, and it cannot prevent a reaction.

22. Snakebite antivenom can itself cause:

    1. A. Tissue necrosis
    2. B. Bleeding from clotting factor loss
    3. C. Allergic reactions
    4. D. Isolated bradycardia
    Show answer

    Answer: C. Allergic reactions

    Antivenom made from animal serum can trigger anaphylaxis or serum sickness. Tissue necrosis and clotting factor loss are effects of the venom, which antivenom is given to limit.

23. Vaccine-related anaphylaxis is:

    1. A. Rare but possible
    2. B. Common, about 1 in 100 doses
    3. C. Mostly seen with live vaccines
    4. D. Delayed by several days
    Show answer

    Answer: A. Rare but possible

    Vaccination sites keep epinephrine available for this reason.

24. Food allergy reactions may be worsened by:

    1. A. A cool shower or bath
    2. B. Drinking plenty of plain water
    3. C. A full night of sleep
    4. D. Exercise, alcohol, NSAIDs
    Show answer

    Answer: D. Exercise, alcohol, NSAIDs

    These cofactors increase absorption or mast cell activation.

25. Insect sting anaphylaxis most often begins:

    1. A. After about 6 hours
    2. B. After 24 hours
    3. C. Within 15 minutes
    4. D. After 3 days
    Show answer

    Answer: C. Within 15 minutes

    Fatal reactions often occur within 10 to 20 minutes, emphasizing early epinephrine.