Cetirizine and Levocetirizine: Allergy Medicine Guide

5 min read · Medicines · By the Asthra Health Care team

What these antihistamines are used for

Cetirizine and levocetirizine are antihistamines used to control allergy symptoms. Levocetirizine is a closely related, purified form of cetirizine. In India, they are widely used for allergic rhinitis, which flares up with dust, pollen, damp monsoon weather and seasonal changes, and for itchy skin rashes called hives or urticaria.

They relieve symptoms but do not cure the allergy itself. Doctors may also use them as part of treatment for allergic conjunctivitis, insect bite reactions and itching from other skin conditions. They are not a treatment for a common cold virus, although they may dry up a runny nose a little.

• Sneezing, runny or itchy nose from dust or pollen allergy
• Watery, itchy eyes
• Hives and itchy skin rashes
• Itching from insect bites

How cetirizine and levocetirizine work

When you meet something you are allergic to, such as house dust mites, the body releases histamine. Histamine makes blood vessels leaky and irritates nerves, causing sneezing, a runny nose, watery eyes, swelling and itching. These medicines block histamine from attaching to its receptors, so symptoms settle.

They are called second-generation antihistamines. Compared with older ones like chlorpheniramine, they enter the brain much less, so they usually cause less sleepiness, though some people still feel drowsy. Their effect lasts most of the day. Relief usually begins within an hour or so. Because they work best when histamine is blocked before it acts, doctors sometimes advise regular use during a bad allergy season rather than waiting for symptoms.

Cetirizine and levocetirizine side effects: common and serious

The most common side effects are drowsiness, tiredness, headache, dry mouth and, occasionally, a mild stomach upset. Children sometimes become restless or irritable instead of sleepy. These effects are usually mild and settle as the body gets used to the medicine.

Serious side effects are rare. They include difficulty passing urine, particularly in older men with an enlarged prostate, fits in people with epilepsy, and allergic reactions to the medicine itself. Some people notice intense itching for a few days after stopping long-term use; tell your doctor if this happens.

Who should take extra care with cetirizine and levocetirizine

People with kidney disease need a doctor's advice, as these medicines are cleared by the kidneys and may build up. Those with epilepsy, urinary retention or an enlarged prostate should also check first. Elderly people may be more sensitive to drowsiness and at risk of falls.

In pregnancy and breastfeeding, cetirizine is one of the more commonly used antihistamines, but you should still only take it after speaking to your doctor. For children, only use syrups or tablets meant for their age group and follow the label or your pharmacist's advice. Very young children should be seen by a doctor before use.

Cetirizine and levocetirizine interactions to know

Alcohol, sleeping pills, some pain medicines, anxiety medicines and older antihistamines can increase drowsiness when taken with cetirizine or levocetirizine. Many cold and cough combinations already contain an antihistamine, so check the label to avoid doubling up. Taking two antihistamines at once adds side effects such as sleepiness and dry mouth without giving better relief.

Doctors sometimes prescribe an antihistamine together with montelukast or a steroid nasal spray when allergy symptoms are persistent, but this is their decision based on your symptoms. Tell your doctor or pharmacist about all medicines and supplements you use. This includes medicines for sleep, anxiety, pain or epilepsy, as well as any herbal products.

Practical tips for using cetirizine and levocetirizine

Follow the label or your pharmacist's advice on how much to take. If the medicine makes you sleepy, taking it in the evening may help, but ask your pharmacist first. Do not drive or operate machinery until you know how it affects you.

Reducing exposure helps as much as medicine. Wash bedsheets in hot water weekly, keep rooms dry and well aired during the monsoon to limit mould, avoid dusting without a mask and keep windows closed on high-pollen or high-pollution days. If you need antihistamines most days, a doctor can look for the trigger and suggest longer-term treatment.

When to talk to your doctor about cetirizine and levocetirizine

See a doctor if allergy symptoms continue for weeks, if hives keep coming back, or if you also have wheezing or night-time cough, which may point to asthma. Seek emergency help for swelling of the lips, tongue or throat, or difficulty breathing. Talk to your doctor or pharmacist if you are unsure which allergy medicine suits you.

This article is general health information, not medical advice. Do not start, stop or combine medicines on your own — always follow your doctor's prescription and ask your pharmacist if unsure.