Zyrtec (Cetirizine). Dosage, Side Effects, Interactions
Zyrtec (Cetirizine) is an antihistamine and one of the most important active ingredients in the treatment of hay fever, allergic rhinitis, allergic conjunctivitis or hives.
Zyrtec (Cetirizine) is used to treat hay fever (associated with sneezing, runny nose, itchy nose, nasal congestion, redness and itching of the eyes, lacrimation), chronic allergic rhinitis, allergic conjunctivitis and chronic idiopathic urticaria (associated with itching, wheal formation, reddening of the skin). . Cetirizine can also be used as a supportive measure in mild forms of asthma of allergic origin.
Depending on the indication, the active ingredient is available on the market in various dosage forms: as film-coated tablets, lozenges or in the form of drops for oral use.
How Zyrtec (Cetirizine) works
Cetirizine has an antiallergic, antihistamine and anti-inflammatory effect. The active ingredient blocks the H1 receptor and is highly selective for it. By doing so, it prevents the appearance or effects of histamine , a mediator of allergic reactions. The selective effect on the H1 receptor lasts for a comparatively long time. Cetirizine inhibits endogenous histamine release, prevents immediate cutaneous allergic reactions and suppresses edematous skin reactions caused by substance P.
After taking the tablets, cetirizine is quickly and well absorbed. Maximum plasma levels can be measured after just 40 to 60 minutes. The active substance is hardly metabolized and 70% is excreted renally. Therefore, the dose may need to be adjusted in patients with renal impairment (see Dosing section).
Dosage of Zyrtec (Cetirizine)
Cetirizine acts quickly and for a long time, which is why it only needs to be taken once a day, preferably in the evening. The tablets are swallowed whole with a glass of water, regardless of meals. Different dosage recommendations apply to different patient groups.
Adults and young people aged twelve and over
1 film-coated tablet of 10 mg cetirizine or 20 drops once a day, preferably in the evening. In asthmatic conditions that are of allergic origin, the dose can be increased to 2 film-coated tablets a day. It should then be taken in the morning and evening (10 mg each).
Children from 2 to 12 years weighing less than 30 kg
½ film-coated tablet with 5 mg cetirizine daily. When using in the form of oral drops: 5 drops twice a day.
Children from 2 to 12 years weighing more than 30 kg
1 film-coated tablet daily, divided into 2 doses of 5 mg cetirizine each (½ film-coated tablet morning and evening). When using in the form of oral drops: 10 drops twice a day.
Patients with renal insufficiency
Here, the dose for adults should be halved, since cetirizine is excreted renally.
Patients with hepatic insufficiency
For them, the dose should be adjusted individually after consultation with the doctor. Possibly he will reduce the dose or increase the interval between intakes.
Duration of treatment
The treatment time depends on the type, duration and course of the symptoms. In general, a therapy of one to six weeks is recommended for hay fever. In asthmatic conditions based on an allergy, a treatment period of up to six months is advisable. Experiences of up to one year are available for chronic complaints such as hives. Children should only take cetirizine for one to four weeks.
If you forget to take it
If you forget to take cetirizine, you should never take twice as much the next time. Treatment is continued at the usual dose.
In case of overdose
In the event of an overdose, drowsiness can occur, but also diarrhea, dizziness or an increased heart rate. In the event of a massive overdose, standard elimination measures such as gastric lavage should be instituted. There is no known antidote and cetirizine is not removable by dialysis, so patients should be monitored.
Medications containing cetirizine should be stored away from heat.
Side effects of Zyrtec (Cetirizine)
The active ingredient is a second-generation anti-allergic, which hardly reaches the brain and therefore causes less tiredness and drowsiness than the first-generation active ingredients. The side effects are listed below in order of frequency.
- dry mouth
- sensory disturbances
- stomach pain
- skin rash
- movement disorders
- abnormal liver function
- weight gain
- anaphylactic shock
- taste disorders
- accommodation disorders
- blurred vision
- oculogyric crisis, especially in children
- angioneurotic edema
- erythema multiforme
- voiding disorders.
Cetirizine is not known to have any interactions with other drugs. The tablets should not be taken with alcohol.
Film-coated tablets with cetirizine must not be taken if:
- Hypersensitivity to the active ingredient or other drug ingredients
- severe kidney disease
- Children under 2 years and infants.
In the case of the following intolerances and intolerances, film-coated tablets containing cetirizine should not be taken:
- hereditary galactose intolerance
- lactase deficiency
- Glucose-galactose malabsorption.
According to animal experiments, cetirizine cannot be expected to damage the fetus, but the active substance should not be taken during pregnancy.
Since excretion in human breast milk has not been investigated to date, but cetirizine passed into breast milk in animal experiments, it should not be taken during breast-feeding.
Patients who are required to drive vehicles, work without a secure footing, or operate hazardous machinery should not exceed the recommended dose of cetirizine, although responsiveness, alertness, and driving characteristics were not affected by the active ingredient in clinical trials.
Further details on this active ingredient can be found in the relevant product information.
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