Below is a comprehensive overview of antihistaminics in pharmacology, covering their composition, mechanism of action, dosage and route, indications, contraindications, drug interactions, side effects (including adverse effects and toxicity), and the nurse’s role. 1. Composition 2. Mechanism of Action 3. Dosage and Route of Administration 4. Indications 5. Contraindications 6. Drug Interactions 7. Side Effects and Adverse Effects 8. Toxicity 9. Role of the Nurse Nurses play a pivotal role