Cetirizine – a tablet for allergies, hay fever, and hives

Cetirizine – a tablet for allergies, hay fever, and hives

Generic name: Cetirizine [se-TIR-a-zeen]
Brand names: Piriteze, Zirtek, Allacan, Benadryl Allergy (UK) / Zyrtec (US)
What it is: Antihistamine
Who should benefit: People with allergies, hay fever, and hives
Tablet forms: 2.5 mg; 5 mg; 10 mg

What is cetirizine?

Cetirizine is a widely used medication prescribed and bought over-the-counter to treat the symptoms of allergic reactions. It is commonly taken to manage seasonal allergies (hay fever) and perennial allergies, which occur year-round.

It belongs to a group of medicines called non-drowsy second-generation antihistamines. Unlike older antihistamines, it is designed to target allergy sites without crossing into the brain in large amounts, making it much less likely to cause sleepiness.

Uses (who should benefit)

Cetirizine is safe and effective for a broad range of people, including adults and children from a young age. It is used for:

• Seasonal allergic rhinitis (hay fever caused by tree, grass, or weed pollen)

• Perennial allergic rhinitis (all-year allergies caused by dust, mould, or animal fur)

• Chronic urticaria (hives, which cause itchy, red, raised skin welts)

• Allergic conjunctivitis (red, itchy, and watery eyes due to an allergic reaction)

Dosage

The usual cetirizine dose is taken once daily, with or without food, and can be taken in the morning or evening:

• Adults and children over 12 years: 10 mg (one tablet) once daily.

• Children (aged 6 to 11 years): 5 mg (half a tablet) twice daily, or 10 mg once daily.

• Children (aged 2 to 5 years): 2.5 mg twice daily, typically given as a liquid solution.

• Kidney disease patients: The dose may need to be reduced to 5 mg once daily by a doctor, depending on how well the kidneys function.

Note: Do not exceed the recommended daily dose. While cetirizine is classified as non-drowsy, taking more than the suggested amount increases the risk of feeling sleepy.

Side-effects

Cetirizine side effects are generally mild, temporary, and affect only a small percentage of people who take it.

• Mild sleepiness or tiredness

• Dry mouth

• Headaches

• Dizziness

• Sore throat or a runny nose (in children)

Serious side effects, such as a severe allergic reaction or difficulty urinating, are exceptionally rare. If you experience unexpected dizziness, confusion, or a rapid heart rate, stop taking the medication and seek medical attention.

How it works

When your body comes into contact with an allergen—such as pollen, dust mites, or pet dander—it triggers your immune system to release a chemical called histamine.

Histamine attaches to specific receptors, causing blood vessels to expand and fluids to leak, which leads to typical allergy symptoms like itching, swelling, and mucus production.

Cetirizine works by binding to these histamine receptors and blocking them. By preventing histamine from locking into place, it stops the allergic cascade, effectively drying up runny noses and calming itchy eyes, throats, or skin.

Monitoring

Because cetirizine has an excellent safety profile and is frequently used over-the-counter, routine medical monitoring is rarely required. However, healthcare providers may consider:

• Kidney function via blood tests in elderly individuals or those with known renal impairment to ensure correct dosing

• Concomitant medication use, as cetirizine can interact with other drugs that cause central nervous system depression, including sedatives or strong painkillers

• The use of alcohol, which can increase the likelihood of drowsiness when combined with an antihistamine

• Symptoms during allergy testing, as cetirizine must be stopped a few days before a skin prick test to avoid masking the body’s natural allergic responses

Other resources

• NHS: About Cetirizine – Medicines Guide

• BNF: Cetirizine Hydrochloride Monograph – British National Formulary

• NICE: Allergic Rhinitis – Prescribing Information

• Mayo Clinic (USA): Cetirizine (Oral Route) Patient Information