Zyrtec (Cetirizine Hydrochloride)

Product of Canada.

Shipped from Canada.

Prescription Required.Product of Canada.Shipped from Canada.

Zyrtec (Cetirizine)

What is Zyrtec?

Suitable for adults and children aged 2 and older, Zyrtec relieves the symptoms caused by allergies and allergic skin conditions. These symptoms can occur after coming into contact with allergens like plant pollen or mold, affecting:

  • The nose
  • The sinuses
  • The throat
  • Other parts of the upper respiratory system

The symptoms can include:

  • Sneezing
  • Runny nose
  • Itchy or watery eyes
  • Itchy throat or nose

Zyrtec also helps to alleviate the effects of skin conditions including hives: itchy rashes from allergies to food or medication.

You do not need a prescription for Zyrtec, which comes in capsule and tablet form, as it can be bought from pharmacies over the counter (OTC) and is not costly. It is also available as a liquid and an injection that would be administered by a healthcare provider. Zyrtec is generally considered a safe and effective drug that may also be recommended by your doctor for either seasonal allergies or those you have throughout the year.

How does it work?

Zyrtec falls into the category of medications named second-generation antihistamines. Specifically, Zyrtec is a histamine receptor antagonist. After encountering substances to which you might be allergic (allergens), histamine, a natural chemical, is produced by the body. Most symptoms from allergic reactions are caused by histamine.

Zyrtec, the brand name for Cetirizine, helps neutralize the mild to moderate symptoms histamine can cause, but does not prevent them. It normally begins working very quickly, within 20 minutes of having taken it, so you should begin feeling the symptoms lessen within an hour of taking Zyrtec. It generally continues working for around 24 hours.

Your condition may impact how long you will need to take Zyrtec, whether it is a one-off dose or ongoing use for seasonal or other types of allergies.

Appearance & Ingredients

Zyrtec is generally available as modified-rectangle-shaped 20 mg tablets that are white, coated, and feature “20” and “P” on one side and nothing on the other. Each tablet contains 20 mg of cetirizine hydrochloride and the following ingredients:

  • corn starch
  • hypromellose
  • lactose
  • magnesium stearate
  • polyethylene glycol
  • povidone
  • titanium dioxide


Whether you are taking Zyrtec in its oral or injection form, you should take it exactly as directed on the label or prescribed by your doctor. You should not use Zyrtec in a higher or lower dosage than has been recommended for you.

Zyrtec capsules and tablets are to be taken by mouth, either with or without food. Chewable Zyrtec tablets must be chewed before being swallowed. Dissolving tablets must not be chewed and should be allowed to dissolve in the mouth whilst swallowing. You can take it with liquid to aid the swallowing of the dissolving tablet.

Zyrtec in its liquid form should be measured carefully using a dosing syringe, but not a regular kitchen spoon.

The Zyrtec injection would be given by a healthcare professional and is generally given for the treatment of hives. It is an infusion injected into a vein once every 24 hours.


Unless the doctor recommends it, children should not take Zyrtec for over 14 consecutive days.

A 5 mg dose is recommended for children between the ages of 2 and 6, either once a day or 2.5 mg in the morning and another 2.5 mg in the evening.

Children between the ages of 6 and 12 should take either a 10 mg dose once a day, or 5 mg in the morning and another 5 mg in the evening.

Adults and children aged 12 and older should take 5 mg to 10 mg once a day, depending on how severe the symptoms are and the condition of the person taking Zyrtec. You should consult your doctor if 10 mg does not bring your symptoms under control.

It is normal for adults aged 65 and over to be recommended a lower dose. 5 mg once a day is recommended, but you should follow your doctor’s instructions.

If your symptoms do not improve or you develop a fever, you should contact your doctor.


An overdose of Zyrtec may result in one or more of the following symptoms:

  • extreme drowsiness
  • vision problems
  • agitation
  • restlessness followed by drowsiness or tiredness
  • rapid heartbeat
  • stomach pain
  • nausea
  • vomiting
  • difficulty walking
  • difficulty swallowing or speaking

Call a doctor if you believe you or someone else has overdosed on Zyrtec. If someone taking Zyrtec collapses, contact the emergency services.

Side Effects

If you are concerned about experiencing side effects from taking Zyrtec, you should talk it over with your doctor and weigh up the risks against the benefits. Many of these side effects may disappear over time or can be managed. Your pharmacist should be able to make recommendations for managing these side effects, however, you should contact your doctor if they become severe or significantly uncomfortable.

The side effects of Zyrtec are not experienced by everyone who takes it, but at least 1% of people taking this medication have experienced those listed below.

  • dizziness
  • dry mouth
  • headache
  • loss of taste
  • sleepiness
  • difficulty sleeping

Serious Side Effects

These serious side effects are rare but can cause serious issues if they are not addressed. If you experience any of these, you should see your doctor as soon as possible.

  • pain or swelling of the eye
  • changes in behavior, such as agitation or aggression
  • blurred vision
  • uncomfortable or painful urination
  • forgetfulness
  • hallucinations
  • new rash or itching after you have stopped the medication
  • restlessness and physical agitation
  • liver problem symptoms, such as:
    • nausea
    • vomiting
    • diarrhea
    • loss of appetite
    • weight loss
    • jaundiced skin or whites of the eyes
    • dark urine, pale stools

Side effects requiring urgent medical attention

If you experience any of the following side effects, discontinue the treatment and immediately seek the attention of a medical professional.

  • serious allergic reaction symptoms, such as:
    • abdominal cramps
    • difficulty breathing
    • nausea and vomiting
    • swelling of the face and throat
  • severe skin reaction symptoms, such as:
    • blistering
    • peeling
    • a large rash
    • a fast-spreading rash
    • a rash with fever or discomfort

Side effects other than those listed above are possible. If any symptoms develop that worry you whilst taking Zyrtec, you should discuss them with your doctor.

Warnings & Precautions

Always check the ingredients of any medication you take for anything you may be allergic to. You should not take Zyrtec if you are allergic to any of the ingredients in Zyrtec or any antihistamines containing hydroxyzine.

Make sure your doctor is aware of any medical conditions or allergies you have as this may impact whether or not they recommend Zyrtec for you.

Before taking Zyrtec you should discuss it with your doctor if you have liver or kidney disease. Your doctor may recommend a lower dosage if they still feel it is safe for you to take Zyrtec. Your doctor may not recommend Zyrtec for you if your kidney function is severely compromised, or they may recommend special monitoring if you take it.

Zyrtec is not usually a cause of drowsiness, but people can react differently to it, especially during the first few doses. Do not drive a vehicle or use machinery until you have taken a few doses and have a better understanding of how your body reacts to Zyrtec.

Pregnancy and breastfeeding

You should not use Zyrtec during pregnancy unless you and your doctor have considered the benefits and risks. You should seek your doctor’s guidance as soon as you become aware that you are pregnant if you become pregnant while using Zyrtec. It is not known whether Zyrtec can be passed from mother to baby through breast milk. However, there is a chance that it can affect your baby if you breastfeed whilst using Zyrtec. You should consult your doctor about whether you should carry on breastfeeding if you are using Zyrtec.


Zyrtec may interact with any of the following drugs, so if you are taking any of them you should let your doctor know or seek guidance from your pharmacist.

  • acetylcholinesterase inhibitors, such as:
    • donepezil
    • galantamine
    • rivastigmine
  • aclidinium
  • alcohol
  • amantadine
  • amiodarone
  • amphetamines, such as:
    • dextroamphetamine
    • lisdexamfetamine
  • other antihistamines, such as:
    • diphenhydramine
    • chlorpheniramine
    • hydroxyzine
  • antipsychotics, such as:
    • chlorpromazine
    • clozapine
    • haloperidol
    • olanzapine
    • quetiapine
    • risperidone
  • apalutamide
  • atropine
  • azelastine
  • “azole” antifungals, such as:
    • fluconazole
    • ketoconazole
    • voriconazole
  • barbiturates, such as:
    • butalbital
    • pentobarbital
    • phenobarbital
  • benzodiazepines, such as:
    • lorazepam
    • diazepam
  • belladonna
  • benztropine
  • betahistine
  • botulinum toxin
  • brimonidine
  • buspirone
  • cannabis
  • carvedilol
  • chloral hydrate
  • clidinium
  • clonidine
  • cyclosporine
  • darifenacin
  • disopyramide
  • domperidone
  • dronedarone
  • eluxadoline
  • entacapone
  • flavoxate
  • flibanserin
  • glucagon
  • glycopyrrolate
  • glycopyrronium
  • hepatitis C antivirals, such as:
    • daclatasvir
    • glecaprevir and pibrentasvir
    • ledipasvir
    • velpatasvir
  • hyaluronidase
  • ipratropium
  • macrolide antibiotics, such as:
    • azithromycin
    • clarithromycin
    • erythromycin
  • metoclopramide
  • mirabegron
  • mirtazapine
  • muscle relaxants, such as:
    • baclofen
    • cyclobenzaprine
    • methocarbamol
    • orphenadrine
  • nabilone
  • narcotic pain medications, such as:
    • codeine
    • fentanyl
    • oxycodone
    • morphine
  • nitroglycerin
  • oxybutynin
  • potassium supplements, such as:
    • potassium chloride
    • potassium citrate
  • pramipexole
  • pramlintide
  • quinidine
  • quinine
  • reserpine
  • rifampin
  • ritonavir
  • ropinirole
  • John’s wort
  • scopolamine
  • seizure medications, such as:
    • carbamazepine
    • clobazam
    • levetiracetam
    • phenobarbital
    • phenytoin
    • primidone
    • topiramate
    • valproic acid
    • zonisamide
  • selective serotonin reuptake inhibitors (SSRIs), such as:
    • citalopram
    • fluoxetine
    • paroxetine
    • sertraline
  • sodium oxybate
  • solifenacin
  • suvorexant
  • tapentadol
  • thiazide diuretics (water pills), such as:
    • hydrochlorothiazide
    • indapamide
    • metolazone
  • tiotropium
  • tolterodine
  • tramadol
  • tranylcypromine
  • tricyclic antidepressants, such as:
    • amitriptyline
    • clomipramine
    • desipramine
    • trimipramine
  • tyrosine kinase inhibitors, such as:
    • dabrafenib
    • imatinib
    • nilotinib
    • sunitinib
  • umeclidinium
  • verapamil
  • zolpidem
  • zopiclone

Frequently Asked Questions

Zyrtec may be prescribed for conditions other than those mentioned above. If you do not know why your doctor has prescribed it for you, you should ask them. It is important not to stop taking Zyrtec without discussing it with your doctor.

It’s important that you do not give your prescribed Zyrtec to anyone else. Even if they have the same symptoms as you, it can be harmful to them if they have not been prescribed it.

For an accurate dose of Zyrtec liquid, you should utilize an oral syringe and not use regular household teaspoons.

Zyrtec, no matter which form you take it in, can be taken with or without food.

Doctors of seniors, or patients with compromised kidneys or livers, may recommend lower doses of Zyrtec.

Many things might affect the dose you are prescribed. Your weight, other medical factors, and other medications you are on can have an impact. Do not take anything other than the dose you have been given by your doctor.

It is vital that you take Zyrtec exactly as your doctor has prescribed, so if you miss a dose you should seek guidance from your doctor. However, do not attempt to give yourself two doses to make up for the one you missed.

Zyrtec should not be disposed of in wastewater or thrown out in the rubbish. You should seek the recommendations of your pharmacist to determine how best to dispose of the medication in your area.

Zyrtec should be stored in a dry place, away from heat and moisture, out of the reach of children, and at room temperature, 59 F to 86 F. Liquid medicines should not be allowed to freeze.

An interaction does not necessarily mean you need to stop taking one. You should speak with your doctor and they will be able to help you manage your medications.

It depends on the situation, but your doctor might suggest:

  • you stop taking the medication
  • you change to a different medication
  • change your dosage of Zyrtec, the other medication, or both
  • leave things as they are.

Other medications may interact with Zyrtec, you should inform your doctor of all prescription, over-the-counter and herbal medicines. They should be made aware of any supplements you’re taking. You should also tell your doctor if you smoke, use street drugs or consume caffeine products.

Other medications may interact with Zyrtec, you should inform your doctor of all prescription, over-the-counter and herbal medicines. They should be made aware of any supplements you’re taking. You should also tell your doctor if you smoke, use street drugs or consume caffeine products.

Zyrtec-D is a combination drug that contains cetirizine and also pseudoephedrine, a decongestant, which is what the “D” stands for. Pseudoephedrine can exacerbate other health conditions as it is a stimulant, so you should discuss taking it with your doctor beforehand. Your doctor may not recommend it if you have any of the following conditions:

  • heart disease
  • thyroid disease
  • diabetes
  • glaucoma
  • high blood pressure
  • enlarged prostate with urinary retention

After taking Zyrtec, you should wait a couple of days before drinking alcohol. This will allow the drug to completely leave your body and avoid the possibility of alcohol exacerbating the potential side effects of Zyrtec.

Cetirizine does not raise blood pressure and higher blood pressure is not known to be a side effect of Zyrtec. However, pseudoephedrine is known to raise blood pressure and is combined with cetirizine in Zyrtec-D.