Cetirizine (Antihistamine, Anti-allergy)

Cetirizine is a type of drug known as an antihistamine. Cetirizine works by binding to histamine H1-receptors on various cells of the body especially in the central nervous system, lungs, and white blood cells. By blocking histamine, it prevents symptoms such as sneezing, itchiness, redness, inflammation, and runny nose.

It is a second-generation antihistamine that causes less drowsiness when taken as compared to first-generation antihistamines (e.g. diphenhydramine).

Know the basics

What is cetirizine used for?

Cetirizine is used to treat the symptoms of following:

• Seasonal allergic rhinitis
• Hay fever
• Vasomotor rhinitis
• Allergic conjunctivitis
• Relieve symptoms of allergic reaction

How should I take cetirizine?

As an oral medication, swallow it whole without chewing or crushing it, unless it is a chewable tablet. Take it with or without meals.

Avoid using cetirizine if you need to be fully alert, such as driving or operating machinery.

How do I store cetirizine?

This product is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using cetirizine?

Before using this drug, tell your doctor if you are/have:

• Pregnant or breastfeeding.
• Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
• An allergy to any of the ingredients of this product.
• Any other illnesses, disorders, or medical conditions.

Is it safe to take cetirizine during pregnancy or breast-feeding?

Unfortunately, there isn’t enough information about the safety of using this drug during pregnancy and breastfeeding. However, it is likely safe to take. Please always consult with your doctor to weigh the potential benefits and risks before taking any medication.

This medication is pregnancy risk category B according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

• A=No risk
• B=No risk in some studies
• C=There may be some risk
• D=Positive evidence of risk
• X=Contraindicated
• N=Unknown

Know the side effects

What are the side effects of cetirizine?

Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:

• Irregular heart rate
• weakness, tremors (involuntary shaking)
• Disturbed sleep or insomnia
• Sleepiness
• Confusion
• Blurry vision
• Decreased urination
• Nausea
• Constipation, diarrhea
• Dry mouth
• Headache

However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with cetirizine?

This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. 

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. 

Drugs with known interactions:

• Other antihistamines
• Sedative-hypnotics (e.g. benzodiazepines)

If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.

Does food or alcohol interact with cetirizine?

This drug may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Do not take this medication or other antihistamines with alcohol as it may induce excessive drowsiness. Taking food with cetirizine may reduce its absorption and efficacy. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with cetirizine?

This drug may interact with underlying conditions. This interaction may worsen your health condition or alter the way the drug works. Therefore, it is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:

• Renal impairment

Understand the dosage

The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

What is the dose for an adult?

Take 10 mg once a day.

For renal impairment, based on creatinine clearance (CrCL in mL/min):

What is the dose for a child?

Ages 2 to 6 years: Give 2.5 mg twice a day.

6 to 12 years: Give 5 mg twice a day.

For over 12 years: Give the same dose as an adult, 10 mg once a day.

How is cetirizine available?

Cetirizine is available in the following dosage forms and strengths:

• Tablet, oral: 10mg.
• Chewable tablet, oral: 5 mg, 10 mg
• Solution, oral: 1mg/ml.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

What should I do if I miss a dose?

If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.