Cetirizine

Key points

• Non-drowsy antihistamine
• Take one tablet daily
• Works within 20-60 minutes, lasts for up to 24 hours

What is cetirizine?

Cetirizine is a non-drowsy antihistamine tablet, which is used to treat symptoms of hay fever and allergy. It works by blocking the release of histamine, a chemical released by the body in response to an allergy.
 

What is cetirizine used for?

Cetirizine is used to treat symptoms of hay fever (allergic rhinitis) and allergy. Symptoms that cetirizine can help to treat include:

• Sneezing
• Runny or blocked nose
• Itchy, watery, or red eyes
• Itchy skin due to hives, eczema, insect bites

How long does cetirizine take to work?

It takes around 20-60 minutes for cetirizine to start working, with the effects lasting for up to 24 hours.

Tip: For long term allergies such as hay fever, start taking cetirizine for 2 weeks before exposure.

Take one tablet daily (with or without food).

Tip: It does not matter what time of day you take cetirizine, as the effects will build up over time. However, it is advisable to take cetirizine at night, in case you experience drowsiness.

Note: Liquid cetirizine is available for children. You should read the patient information leaflet for a dosing chart, which will depend on the age or weight of the child.
 

Can I take 20mg of cetirizine (two tablets)?

The maximum dose of cetirizine in 24 hours in one 10mg tablet. Taking more than this is considered an overdose. Do not take more than one tablet daily.

Active ingredients: Cetirizine hydrochloride or cetirizine dihydrochloride (10mg)

Inactive ingredients: Lactose, maize starch, microcrystalline cellulose, colloidal anhydrous silica, talc magnesium stearate, hypromellose, sodium citrate, titanium dioxide (E171) and macrogol 4000.

Note: Whilst the active ingredients will remain the same, there may be differences within the inactive ingredients. Read the patient information for a full list of ingredients.

Like all medication, cetirizine can cause side effects. Side effects of cetirizine include:

Common (affecting up to 10% of users):

• Sleepiness
• Headache
• Dizziness
• Nausea
• Dry mouth
• Diarrhoea

Uncommon (affecting up to 1% users):

• Skin irritation
• Itchy skin or rash
• Stomach pain
• Extreme tiredness

Seek medical attention if you experience signs of an allergic reaction such as:

• Swelling of the throat, eyes, nose, or mouth

Does cetirizine make you drowsy?

Cetirizine is a non-drowsy antihistamine; however, drowsiness is a side effect which can affect up to 10% of users.

Tip: If you are taking cetirizine for the first time, take a tablet at night to assess your response.

Do not take cetirizine if:

• You are allergic to any of the ingredients
• You have stage 4 kidney disease

Speak to your doctor or pharmacist before taking cetirizine if:

• You have kidney problems
• You have problems urinating
• You have epilepsy
• You are due to have an allergy test (you will need to stop taking cetirizine a few days before your test)

Cetirizine is safe to take in pregnancy, however, other antihistamines such as loratadine have more evidence to support use during pregnancy.

Speak to your doctor or pharmacist if you wish to use cetirizine whilst pregnant.

Cetirizine is usually safe to take whilst breastfeeding if your baby is healthy.

Small amounts can pass through the breast milk. If your baby is not feeding as normal, seems more tired than usual, or displays any other unusual behavior, stop taking cetirizine and speak to your doctor.

Speak to your doctor or pharmacist if you wish to use cetirizine whilst breastfeeding.

Cetirizine is safe to take with most medication. Speak to your doctor or pharmacist if you are taking:

• Betashistine
• Isocarboxazid
• Phenelzine
• Tranylcypromine

You may still be able to take cetirizine, but your dosing regime may need altering.
 

Can you take cetirizine with alcohol?

Drinking alcohol while taking cetirizine can make you feel very drowsy.

Cetirizine hydrochloride vs cetirizine dihydrochloride

• Both are the same compound, with the same molecular weight. There is no difference between the two

Cetirizine vs loratadine

• Cetirizine works faster than loratadine
• Loratadine lasts longer than cetirizine
• You cannot take cetirizine and loratadine together, or one the same day
• Both are similar in price

Cetirizine vs fexofenadine

• Cetirizine is more likely to cause drowsiness than fexofenadine
• Cetirizine is faster acting, taking 20-60 minutes to work
• Cetirizine is cheaper than fexofenadine
• You cannot take cetirizine and fexofenadine at the same time, or on the same day

Cetirizine vs levocetirizine

• Cetirizine is more likely to cause drowsiness
• Levocetirizine is a prescription only medication whilst cetirizine can be bought over the counter
• Cetirizine is cheaper than levocetirizine

1. NHS UK. (n.d.). Cetirizine. Retrieved February 21, 2024, from https://www.nhs.uk/medicines/cetirizine/

2. British National Formulary. (n.d.). Cetirizine Hydrochloride. Retrieved February 21, 2024, from https://bnf.nice.org.uk/drugs/cetirizine-hydrochloride/