Cetirizine

Description

Cetirizine is a second-generation antihistamine that provides effective relief from allergy symptoms without causing significant drowsiness. It works by blocking histamine, a substance produced by the body during an allergic reaction, thereby alleviating undesirable symptoms.

Uses / Indications

• Seasonal allergic rhinitis (hay fever)
• Perennial allergic rhinitis
• Chronic idiopathic urticaria (persistent hives)
• Sneezing, runny nose, itchy or watery eyes
• Itchy throat or nose
• Skin reactions such as itching or rashes

Dosage and Administration

Adults and children 6 years and older:
10 mg once daily (typically 1 tablet or 10 mL syrup)

Children aged 2–5 years:
5 mg once daily (usually 5 mL syrup or ½ tablet if suitable)

Note: Dosage may vary based on individual health conditions or doctor’s recommendations.

How It Works (Mechanism of Action)

Cetirizine selectively inhibits peripheral H1 histamine receptors, preventing histamine from binding and triggering allergic reactions. It is designed to minimize sedation compared to older antihistamines by limiting its ability to cross the blood-brain barrier.

Side Effects

Common side effects:

• Drowsiness (less common than first-generation antihistamines)
• Dry mouth
• Fatigue
• Stomach upset

Rare/serious side effects:

• Rapid or irregular heartbeat
• Severe allergic reactions (hives, swelling, dizziness)
• Jaundice (very rare)

If serious side effects occur, seek medical attention immediately.

Precautions / Warnings

• Inform your doctor if you have liver problems, kidney issues, or are pregnant/breastfeeding
• Use caution when combining with other sedative medications
• May interfere with allergy skin tests—consult your doctor about stopping it a few days prior to testing

Drug Interactions

May interact with:

• Alcohol (may enhance sedative effects)
• Other antihistamines
• Certain antidepressants or anxiety medications (rare)
• Medications that affect liver enzymes

Always inform your healthcare provider of all medications and supplements you’re taking.

Storage Instructions

• Store at room temperature (20°C–25°C / 68°F–77°F)
• Keep away from moisture, heat, and direct light
• Do not freeze liquid forms
• Keep out of reach of children

Missed Dose / Overdose

Missed a dose?
Take it as soon as you remember. If it’s almost time for your next dose, skip the missed one. Do not double up.

Overdose symptoms:

• Extreme drowsiness
• Rapid heartbeat
• Headache
• Nausea

Contact a poison control center or seek emergency medical help immediately if overdose is suspected.

Contraindications

• Allergic to Cetirizine or hydroxyzine
• Previous serious reactions to antihistamines

Brand Names / Alternatives

• Zyrtec
• Alleroff
• Reactine (in some regions)
• Generic name: Cetirizine