Cetirizine

What is cetirizine?

Cetirizine is an antihistamine that relieves allergy symptoms by blocking histamine, a substance in the body that triggers allergic reactions such as sneezing, itching, runny nose, and watery eyes. It is commonly used to treat conditions like hay fever, hives, and other allergic reactions[1].

What is cetirizine used to treat?

Cetirizine is used to treat[1]: 

• Hay fever (seasonal allergic rhinitis) 

• Perennial allergic rhinitis (year-round allergies like dust or pets) 

• Conjunctivitis (red, itchy eyes) 

• itching associated Eczema (atopic dermatitis) 

• Hives (urticaria) – itchy, raised rashes 

• Reactions to insect bites and stings 

• Chronic idiopathic urticaria (long-term hives with no known cause) 

How does cetirizine work?

Cetirizine works by blocking the effects of histamine, a substance in the body that causes allergic symptoms such as sneezing, itching, watery eyes, and swelling. As a non-drowsy antihistamine, it is less likely to cause sleepiness compared to older antihistamines like chlorphenamine. Cetirizine typically starts relieving symptoms within 30–60 minutes of taking a dose[1].  

Who can take cetirizine?

Cetirizine is suitable for most adults and children, depending on their age. Children’s doses are based on age and weight, and specific formulations (e.g., liquid) are available for younger children[1]. 

It may not be suitable for some people, consult a doctor or pharmacist if you[1]: 

• are allergic to cetirizine other antihistamines, or any ingredients in the product 

• have severe kidney failure  

• Are breastfeeding, as cetirizine passes into breast milk in small amounts 

Always read the Patient Information Leaflet and consult a healthcare professional before starting treatment[2]. 

How do you take cetirizine?

Cetirizine comes as tablets, capsules, or liquid. The tables or capsules should be swallowed whole with a glass of water. It can be taken with or without food[1]. 

If you take the liquid form, it should come with a syringe or spoon designed to hold the correct amount. If you do not have either, ask your pharmacist do not use a kitchen teaspoon as it may lead to incorrect dosing. 

What is the typical dosage of cetirizine?

The tablets or capsules are typically 10mg, and the liquid medicine is 1mg per 1ml (5mg per 5ml). Standard dosages are[1]: 

• Adults and children over 12 years: 10mg once daily 

• Children 6–12 years: 5mg twice daily  

• Children 2–6 years: 2.5mg twice daily 

• Children under 2: Only prescribed by the doctor and based on weight 

Always follow the dosage on the label or as prescribed by your doctor or pharmacist. 

Can you stop taking cetirizine?

You can stop taking cetirizine when your symptoms improve, as it is typically used as needed for allergies. In rare cases, particularly with long-term daily use for chronic hives, stopping suddenly may cause rebound itching. If you have been taking cetirizine daily for an extended period, consult your doctor before stopping to discuss any potential effects[1]. 

What do you do if you take too much cetirizine?

Cetirizine is generally safe, but taking too much may cause symptoms such as headaches, drowsiness, fast heartbeat, confusion, or restlessness. If you or your child takes more than the recommended dose, contact NHS 111 for advice, even if no symptoms are present. In case of severe symptoms, call 999 or go to A&E immediately[1].

What do you do if you forget to take a dose of cetirizine?

If you forget a dose of cetirizine, take it as soon as you remember. Unless it is almost time to take your next dose. In that case, skip the missed dose and continue with your regular schedule. Never take 2 doses at the same time. Missing a dose may cause allergy symptoms to return, so try to take cetirizine as prescribed[1]. 

What are the side effects of cetirizine?

The most common side effects include[1]: 

• Headache 

• Dry mouth 

• Drowsiness (less common than older antihistamines) 

• Dizziness 

• Nausea or diarrhoea 

• Fatigue 

Serious side effects, such as a severe allergic reaction (anaphylaxis, with symptoms like swelling, difficulty breathing, or rash), are very rare. If you experience these, call 999 or go to A&E immediately. 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Medicines you can and can’t take with cetirizine

Cetirizine has a low risk of drug interactions, but caution is advised with[1]: 

• Other sedating medications (e.g., benzodiazepines, opioid painkillers, or sleeping pills), as they may increase drowsiness. 

• Medications that cause dry mouth or difficulty urinating (e.g., certain antidepressants or anticholinergics). 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

Frequently asked questions about cetirizine

Will cetirizine affect my contraception? 

Cetirizine does not affect any type of contraception, including hormonal methods like the pill or emergency contraception[1]. 

Is cetirizine safe during pregnancy? 

Cetirizine is generally considered safe during pregnancy, but you should consult your doctor before use, especially in the first trimester[1]. 

Is cetirizine safe while breastfeeding?  

Cetirizine passes into breast milk in small amounts. Consult your doctor to weigh the benefits and risks before use[1]. 

Can I drive or ride a bike after taking cetirizine? 

Cetirizine is a non-drowsy antihistamine, but some people may feel sleepy. Avoid driving, cycling, or operating machinery if you feel drowsy until you know how cetirizine affects you[1]. 

Can I take cetirizine every day? 

Yes, cetirizine can be taken daily for ongoing allergies, but long-term use should be monitored by a doctor[1]. 

Is cetirizine the same as loratadine? 

Both are non-drowsy antihistamines, but they are different drugs. Some people may respond better to one than the other, so consult your doctor if one is ineffective[1].

Can I drink alcohol while on cetirizine 

It is best to avoid alcohol when you are taking cetirizine as it  as it may increase the risk of drowsiness[1]. 

For the official NHS guide to cetirizine, visit their website.