📌Introduction
Antihistamines are an important topic in pharmacology and are frequently studied by B.Pharm, D.Pharm, and other pharmacy students. Questions related to their classification, mechanism of action, therapeutic uses, adverse effects, and important drug examples are commonly included in pharmacy examinations and competitive exams.
H1 antihistamines are mainly used to reduce symptoms associated with allergic conditions such as sneezing, itching, runny nose, watery eyes, and urticaria. They are broadly classified into first-generation and second-generation antihistamines, with differences in central nervous system penetration and sedation being important points for examination.
In this post, we have compiled 30 important MCQs on antihistamines, covering their classification, mechanism of action, uses, adverse effects, and important examples. Each question includes four options, the correct answer, and a short explanation to make revision easier.
These questions can help pharmacy students test their understanding of antihistamines and identify areas that may require further revision.
1. Antihistamines block which receptor?
A) H2
B) H1
C) Dopamine
D) Serotonin
✔ Answer: B) H1
➜ Explanation: They block H1 receptors to reduce allergic reactions.
2. Histamine is released during:
A) Digestion
B) Allergy
C) Sleep
D) Exercise
✔ Answer: B) Allergy
3. First-generation antihistamines cause:
A) Alertness
B) Sedation
C) Hypertension
D) Weight loss
✔ Answer: B) Sedation
4. Which is a first-generation antihistamine?
A) Cetirizine
B) Loratadine
C) Diphenhydramine
D) Fexofenadine
✔ Answer: C) Diphenhydramine
5. Which is second-generation antihistamine?
A) Promethazine
B) Chlorpheniramine
C) Cetirizine
D) Diphenhydramine
✔ Answer: C) Cetirizine
6. Second-generation drugs cause:
A) More sedation
B) Less sedation
C) Kidney damage
D) Liver failure
✔ Answer: B) Less sedation
7. Antihistamines are used in:
A) Diabetes
B) Allergy
C) Cancer
D) Hypertension
✔ Answer: B) Allergy
8. Motion sickness is treated by:
A) NSAIDs
B) Antibiotics
C) Antihistamines
D) Antacids
✔ Answer: C) Antihistamines
9. Which drug is sedative?
A) Loratadine
B) Fexofenadine
C) Diphenhydramine
D) Cetirizine
✔ Answer: C) Diphenhydramine
10. Antihistamines act by:
A) Increasing histamine
B) Blocking histamine
C) Destroying bacteria
D) Increasing insulin
✔ Answer: B) Blocking histamine
11. Histamine causes:
A) Sleep
B) Allergy symptoms
C) Growth
D) Digestion
✔ Answer: B) Allergy symptoms
12. Which crosses BBB?
A) Second gen
B) First gen
C) Antibiotics
D) NSAIDs
✔ Answer: B) First gen
13. Which is non-sedating?
A) Diphenhydramine
B) Promethazine
C) Loratadine
D) Chlorpheniramine
✔ Answer: C) Loratadine
14. Antihistamines reduce:
A) Blood sugar
B) Allergy
C) Oxygen
D) Insulin
✔ Answer: B) Allergy
15. Side effect of first gen:
A) Sedation
B) Energy
C) Growth
D) Appetite
✔ Answer: A) Sedation
16. Dry mouth is due to:
A) Anticholinergic effect
B) Insulin
C) Hormones
D) Enzymes
✔ Answer: A) Anticholinergic effect
17. Which drug is used in urticaria?
A) Cetirizine
B) Insulin
C) Aspirin
D) Penicillin
✔ Answer: A) Cetirizine
18. Promethazine is:
A) Antibiotic
B) Antihistamine
C) NSAID
D) Antacid
✔ Answer: B) Antihistamine
19. Second-generation drugs have:
A) High sedation
B) Low sedation
C) No effect
D) Toxicity
✔ Answer: B) Low sedation
20. Antihistamines are contraindicated in:
A) Allergy
B) Glaucoma
C) Fever
D) Pain
✔ Answer: B) Glaucoma
21. Which is used in common cold?
A) Antibiotics
B) Antihistamines
C) Insulin
D) Steroids
✔ Answer: B) Antihistamines
22. Which effect is anti-pruritic?
A) Pain relief
B) Itching relief
C) Fever
D) Sleep
✔ Answer: B) Itching relief
23. H1 receptor is responsible for:
A) Acid secretion
B) Allergy
C) Insulin
D) Growth
✔ Answer: B) Allergy
24. Which is safest (less sedative)?
A) Diphenhydramine
B) Promethazine
C) Fexofenadine
D) Chlorpheniramine
✔ Answer: C) Fexofenadine
25. Which is used for insomnia?
A) Loratadine
B) Cetirizine
C) Diphenhydramine
D) Fexofenadine
✔ Answer: C) Diphenhydramine
26. Antihistamines may cause:
A) Dry mouth
B) Growth
C) Energy
D) Weight loss
✔ Answer: A) Dry mouth
27. Which generation crosses BBB?
A) First
B) Second
C) Third
D) None
✔ Answer: A) First
28. Which is long-acting?
A) First gen
B) Second gen
C) NSAIDs
D) Antibiotics
✔ Answer: B) Second gen
29. Antihistamines block:
A) Enzymes
B) Hormones
C) Receptors
D) DNA
✔ Answer: C) Receptors
30. Best use of antihistamines:
A) Infection
B) Allergy
C) Diabetes
D) Cancer
✔ Answer: B) Allergy
🎯 Conclusion
Antihistamines are an important pharmacology topic, and understanding their classification, mechanism, uses, and adverse effects is essential for pharmacy examinations and MCQ-based tests.
The most important points to remember include the difference between first-generation and second-generation H1 antihistamines, the greater sedative potential of many first-generation drugs, and the common therapeutic uses of antihistamines in conditions such as allergic rhinitis and urticaria.
Practising MCQs regularly can help strengthen these concepts and improve recall during examinations. We hope these 30 antihistamine MCQs with answers and explanations help you revise the topic effectively and build confidence in pharmacology.
Keep practising, revise important drug examples regularly, and continue testing yourself with pharmacy MCQs.
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