Brand names [cetirizine] AllerTek, Benadryl, Boots Hayfever and Allergy Relief, Piriteze, Pollenshield Hayfever, Zirtek; [levocetirizine] Xyzal
Used in the following combined preparations None
QUICK REFERENCE
Drug group Antihistamine
Overdose danger rating Medium
Dependence rating Low
Prescription needed Yes (levocetirizine); No (cetirizine)
Available as generic Yes
GENERAL INFORMATION
Cetirizine and levocetirizine are long-acting antihistamines. Their main use is in the treatment of allergic rhinitis, particularly hay fever. Both drugs are also used to treat a number of allergic skin conditions, such as urticaria (hives).
The principal difference between these medicines and traditional antihistamines such as chlorphenamine (chlorpheniramine) is that they have less sedative effect on the central nervous system and may therefore be suitable for people when they need to avoid sleepiness (for example, when driving or at work). However, because these drugs can cause drowsiness in some people, you should learn how cetirizine and levocetirizine affect you before you undertake any activities that require concentration.
INFORMATION FOR USERS
Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.
How taken/used Tablets, liquid.
Frequency and timing of doses 1–2 x daily.
Dosage range Cetirizine 10mg daily (adults and children over 6 years); 5mg daily (children 2–5 years for hayfever only). Levocetirizine 5mg daily.
Onset of effect 1–3 hours. Some effects may not be felt for 1–2 days.
Duration of action Up to 24 hours.
Diet advice None.
Storage Keep in original container at room temperature out of the reach of children.
Missed dose No cause for concern, but take as soon as you remember. If your next dose is due within 8 hours, take a single dose now and skip the next.
Stopping the drug Can be safely stopped as soon as you no longer need it.
Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may cause nausea or drowsiness and have adverse effects on the heart. Notify your doctor.
POSSIBLE ADVERSE EFFECTS
The most common side effects are drowsiness, dry mouth, and fatigue. Headache and diarrhoea may also occur. The side effects of cetirizine may be reduced if the dose is taken as 5mg twice a day (adults and children over 6 years). If the adverse effects are severe, discuss with your doctor.
INTERACTIONS
Anticholinergic drugs The anticholinergic effects of cetirizine and levocetirizine may be increased by all drugs that have anticholinergic effects, including antipsychotics, tricyclic antidepressants, and some drugs for parkinsonism.
Sedatives Cetirizine and levocetirizine may increase the sedative effects of anti-anxiety drugs, sleeping drugs, antidepressants, and antipsychotic drugs.
Allergy tests Antihistamines should be discontinued about 2 days before allergy skin testing. Discuss details in advance with your allergy clinic; timings of discontinuation vary from clinic to clinic.
SPECIAL PRECAUTIONS
Be sure to consult your doctor if:
· You have long-term liver or kidney problems.
· You have glaucoma.
· You are taking other medicines.
Pregnancy Safety in pregnancy not established. Discuss with your doctor.
Breast-feeding The drug passes into the breast milk. Discuss with your doctor.
Infants and children Not recommended under 2 years (cetirizine): not recommended under 6 years (levocetirizine).
Over 60 No problems expected.
Driving and hazardous work Avoid such activities until you have learned how cetirizine and levocetirizine affect you because the drug can cause drowsiness in some people.
Alcohol Keep consumption low.
PROLONGED USE
No problems expected.