Cetirizine is an antihistamine medication that decreases histamine production in the body. Histamine is a substance that can cause allergy or cold symptoms like sneezing, a stuffy nose, a runny nose, itchy eyes or itchy skin. Therefore, cetirizine can be taken to treat allergies or relieve cold symptoms.

This medication is available in pharmacies and drugstores, under the trade name Zyrtec or as its generic form under the name cetirizine dihydrochloride.

Cetirizine can be purchased in the form of tablets or oral solution, and can be taken by adults or children over 2 years of age. It should only be taken as advised by a doctor or pharmacist.

What is it for

Cetirizine can be used to relieve symptoms of allergies or allergic rhinitis. It can help to manage an itchy nose, runny nose, sneezing, itchy eyes, increased tearing, red skin or itchy skin. It can also be beneficial for managing cold and flu symptoms.

How to take

Cetirizine should be taken orally with a glass of water, before or after meals. It should be taken in the dosing and duration times established by your doctor.

If you forget to take a dose, take it as soon as you remember. However, if your next dose is coming up, skip the missed dose and wait for the next time to take it. Do not double a dose to make up for a forgotten dose.

How cetirizine is taken depends on the form of this medication:

1. 10 mg tablets

Cetirizine in the form of tablets is should be taken whole, without breaking or chewing it, as the tablet has a coating to prevent stomach irritation.

These tablets can be taken by adults or children over 12 years of age. The normally recommended dose is one 10 mg tablet taken once a day, orally. If the child has a kidney problem, the doctor must adjust the dose according to the child's weight and kidney function.

2. Oral solution/syrup

Cetirizine oral solution is sold in 120mL bottles, and is taken using the dosing syringe doser that comes in the package. Dosing depends on the person's age:

Adults and children over 12 years old: 5 to 10 mL of the oral solution, once a day. Do not take more than 10 mL in 24 hours;
Children aged 6 to 11 years old: 5 mL of the oral solution, which is equivalent to a dose of 5 mg of cetirizine every 12 hours. Do not administer a dose greater than 10 mL within 24 hours;
Children aged 2 to 5 years old: 2.5 mL of the oral solution, which is equivalent to a dose of 2.5 mg of cetirizine every 12 hours. Do not administer a dose greater than 5 mL within 24 hours.

It is important to adhere to the treatment plan as outlined by your doctor. Treatment with cetirizine is generally short, and it is usually discontinued once symptoms disappear.

3. Drops

Cetirizine drops can be found in bottles of 10, 15 or 20 ml, and should be administered with the dropper that comes in the package. The normally recommended doses are as follows:

Adults and children over 12 years of age: 20 drops (10 mg) every 24 hours
Children between 6 and 12 years old: 10 drops (5 mg) every 12 hours
Children between 2 and 6 years old: 5 drops (2.5 mg) every 12 hours

20 drops is equivalent to 1 ml, which is 10 mg of cetirizine. The drops can be poured onto a spoon, or diluted in water as advised by your pharmacist.

Possible side effects

Some of the most common side effects of cetirizine include:

Drowsiness
Headache
Fatigue
Dizziness
Stomach ache
Diarrhea
Nausea
Dry mouth
Agitation
Sore throat
Irritation of the nasal mucosa

When taking cetirizine, certain activities, like driving, using heavy machinery or performing dangerous activities should be avoided or exercised with caution. Furthermore, the use of alcohol can increase the effects of drowsiness and dizziness if consumed with cetirizine, and should therefore be avoided.

Patients with an allergy to cetirizine may present with symptoms like a feeling of a swollen throat, difficulty breathing, hives and swelling in the face, mouth or tongue. If you notice these symptoms, stop taking cetirizine immediately and seek urgent medical assistance.

You should also proceed to a hospital if you overdose on cetirizine and notice symptoms like a rapid or irregular heartbeat, weakness, tremors, insomnia, agitation, confusion, vision problems, or reduced urination.

Contraindications for use

Cetirizine should not be taken by children under 2 years of age, pregnant or breastfeeding women, or people who have kidney failure.

This medication should also not be taken by people who are allergic to cetirizine.