Active ingredient: cetirizine hydrochloride
This medicine is an antihistamine used to treat allergies of many kinds, or to prevent them. It does not help in a severe allergic reaction (anaphylaxis), where an adrenaline (epinephrine) injection may be needed.
How it acts in the body
Only very small amounts of cetirizine reach the brain, so it doesn't cause the drowsiness typical of older antihistamines, although it can still cause mild sleepiness.
Forms
Tablets or syrup, both absorbed quickly. Levels peak within an hour of taking it, and the effect lasts up to 24 hours. Its half-life is 8 hours. About 70% leaves the body through the kidneys within 72 hours, about half of it unchanged.
It can be prescribed together with pseudoephedrine hydrochloride. The brand Zyrtec is made by McNeil-PPC, but many companies sell cetirizine under other brand names.
Dose
Once a day, with or without food. If there's no improvement within three days, or the symptoms haven't gone within six weeks, see a doctor to change the medicine.
Uses
Allergy symptoms of all kinds, such as a runny nose, itching, hives and watery eyes.
Side effects
Sleepiness, tiredness and a dry mouth. Children may get stomach pain and vomiting; see a doctor if this lasts or gets worse.
Watch out for an allergy to antihistamines. A severe allergic reaction is rare, but its signs include itching, redness, swelling (especially of the face, throat and tongue), severe dizziness and trouble breathing.
Take care when driving or doing dangerous work, and limit alcohol.
Precautions
In pregnancy, use it only when needed. Kidney function falls with age, so take care when giving it to older people.
Interactions
It may interact with other antihistamines, epilepsy drugs, sleeping pills and anti-anxiety medicines, muscle relaxants, painkillers (such as codeine) and psychiatric drugs. It can also add to the drowsiness caused by cold and flu remedies.
Like
Love
Angry
Dislike
