Dose and Dosage:
- The typical adult dose of cetirizine for allergic rhinitis or urticaria is 10 mg orally once daily.
- For children aged 6 to 12 years, the recommended dose is usually 5 mg orally once daily.
- Cetirizine is available in various formulations, including tablets, chewable tablets, and syrup.
Frequency:
- Cetirizine is typically taken once daily, preferably at the same time each day.
Route of Administration (ROA):
- Cetirizine is administered orally, usually in the form of tablets, chewable tablets, or syrup.
Mechanism of Action (MOA):
- Cetirizine is a second-generation antihistamine that selectively antagonizes the histamine H1 receptor. By blocking the effects of histamine, cetirizine alleviates allergy symptoms such as sneezing, itching, watery eyes, and runny nose.
Pharmacokinetics (PK):
- Cetirizine is rapidly absorbed after oral administration, with peak plasma concentrations achieved within approximately 1 hour.
- It undergoes minimal metabolism in the liver and is primarily eliminated unchanged in the urine.
- The elimination half-life of cetirizine is approximately 7 to 10 hours in adults.
Pharmacodynamics (PD):
- Cetirizine provides symptomatic relief of allergic conditions by blocking the action of histamine at H1 receptors in various target tissues, including the nasal mucosa, respiratory tract, and skin.
Pathophysiology:
- Cetirizine is indicated for the relief of symptoms associated with allergic rhinitis (hay fever) and chronic idiopathic urticaria (hives) in adults and children.
Indications:
- Allergic Rhinitis: Cetirizine is effective in the management of symptoms such as sneezing, itching, nasal congestion, and rhinorrhea associated with seasonal or perennial allergic rhinitis.
- Urticaria: Cetirizine can provide relief from the itching and hives associated with chronic idiopathic urticaria.
Contraindications:
- Hypersensitivity: Cetirizine should not be used in patients with a known hypersensitivity to cetirizine or any of its components.
- Severe Renal Impairment: Dosage adjustments may be necessary in patients with severe renal impairment or end-stage renal disease.
Drug Interactions:
- Cetirizine may interact with other medications that depress the central nervous system, such as alcohol, sedatives, and tranquilizers, potentially enhancing their effects.
- Concomitant use of cetirizine with other antihistamines or drugs with anticholinergic properties may increase the risk of side effects such as drowsiness and dry mouth.
Monitoring and Laboratory Tests:
- There are no specific monitoring parameters or laboratory tests routinely recommended for patients taking cetirizine. However, healthcare providers may monitor treatment response and adverse effects during clinical follow-up.
Why is this medication prescribed?
Cetirizine is prescribed to relieve symptoms of allergic conditions such as hay fever (allergic rhinitis) and chronic hives (urticaria). It works by blocking the action of histamine, a substance in the body that causes allergy symptoms.
How should this medicine be used?
- Follow the instructions provided by your doctor or pharmacist.
- Take cetirizine orally with or without food, as directed by your healthcare provider.
- Use a measuring device to ensure accurate dosage if using liquid formulation.
- Do not exceed the recommended dosage or take it more frequently than prescribed.
Other uses for this medicine
Cetirizine may sometimes be prescribed for other conditions or purposes not listed here. Follow your doctor’s instructions for its appropriate use.
What special precautions should I follow?
- Inform your doctor about any allergies, medical conditions, or medications you are currently taking, including over-the-counter drugs and supplements.
- If you are pregnant or breastfeeding, consult your doctor before using cetirizine.
- Use caution while driving or operating machinery as cetirizine may cause drowsiness or dizziness.
- Avoid alcohol consumption while taking cetirizine as it may worsen certain side effects.
What special dietary instructions should I follow?
No special dietary instructions are typically required while taking cetirizine. However, maintaining a balanced diet and adequate hydration can support overall health and well-being.
What should I do if I forget a dose?
If you miss a dose of cetirizine, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up.
What side effects can this medication cause?
Common side effects of cetirizine may include:
- Drowsiness
- Dry mouth
- Headache
- Fatigue
- Nausea
- Dizziness
Rare but serious side effects may include allergic reactions such as rash, itching, swelling, severe dizziness, or trouble breathing. Seek immediate medical attention if you experience any severe or persistent side effects.
What should I know about storage and disposal of this medication?
- Store cetirizine at room temperature away from light and moisture.
- Keep it out of reach of children and pets.
- Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard unused medication or expired supplies following local regulations.
In case of emergency/overdose
If you suspect an overdose or experience severe symptoms such as extreme drowsiness, confusion, or seizures, seek emergency medical attention immediately. Contact a poison control center or your local emergency room for assistance.