What is Cetirizine Hydrochloride?

Cetirizine hydrochloride, commonly known simply as cetirizine, is a second-generation antihistamine used to relieve symptoms of hay fever and other upper respiratory allergies. It works by blocking the effects of histamine, a chemical released in the body during an allergic reaction. Here we explore what cetirizine is, how it works, common uses and side effects.

History and Development

Cetirizine was developed and patented by UCB Pharma in 1985. It was designed to be a metabolite of hydroxyzine, an earlier antihistamine, but with a more favorable safety profile due to less sedation. Initial clinical trials found it to be effective at treating symptoms of seasonal allergic rhinitis or hay fever without the undesirable drowsiness seen with older antihistamines. Cetirizine was approved for medical use in the European Union in 1988 and in the United States in 1995.

Today, it is one of the most commonly prescribed antihistamines worldwide. It is sold under various brand names including Reactine, Zyrtec, Cetrin and Allertec among many others. Generic versions are also widely available. Cetirizine remains a very popular treatment option for seasonal and perennial allergic rhinitis.

Mechanism of Action

Histamine is a chemical messenger released by the body in response to an allergen like pollen, dust or animal dander. It triggers symptoms characteristic of allergies like sneezing, itchy/watery eyes, runny nose and congestion. Cetirizine Hydrochloride works by selectively blocking histamine H1 receptors in cells.

When histamine binds to these receptors on sensory nerve endings in tissues like the nose and eyes, it causes them to send signals to the brain which are interpreted as allergy symptoms. By plugging H1 receptor sites, cetirizine prevents histamine from triggering these effects, providing effective relief. It has little to no activity at other histamine receptor subtypes.

Common Uses

The primary medical use of cetirizine is for the treatment and prevention of symptoms from seasonal allergic rhinitis, commonly known as hay fever. It may be prescribed for relief of sneezing, itchy/runny nose and congestion caused by pollen and other outdoor allergens. Cetirizine is also effective at managing perennial allergic rhinitis symptoms caused by indoor allergens like dust mites and pet dander present year-round.

It can be used to relieve itching and hives caused by both seasonal and perennial allergic reactions involving the skin. Cetirizine is occasionally prescribed for allergy symptoms affecting other parts of the body as well, such as itchy/watery eyes or an itchy throat. While not its primary indication, studies show cetirizine may also provide symptomatic relief from chronic idiopathic urticaria or chronic hives of unknown cause.

Safety and Side Effects

Overall, cetirizine is generally well-tolerated by most adults and children over age 6. Common side effects tend to be mild and may include headache, dry mouth, fatigue or drowsiness in some cases. However, cetirizine is less likely to cause drowsiness than older antihistamines. Serious side effects are rare when taken as directed.

As with any medication, cetirizine should be used with caution by pregnant/breastfeeding women after discussing with a doctor. Extra monitoring may be required in elderly patients or those with liver or kidney disease. Interactions can occur if taken with other sedating drugs like alcohol or opioids. Cetirizine does not usually interact significantly with other medications but check with a pharmacist if any concerns.

Usage and Guidance

The standard adult dosage of cetirizine is one 10mg tablet taken once per day, usually in the morning with or without food. For children ages 6 to 11, the dosage is 5mg once daily. Cetirizine acts within an hour and provides full relief of symptoms for 24 hours in most cases.

To get the most benefit, cetirizine treatment for allergies should start 1-2 weeks before the expected allergy season. It takes continuous daily use to block histamine effects around the clock. For best results, follow the dosage schedule exactly as prescribed or advised by the pharmacist or doctor and allow a few days to take full effect before deciding if adjustments are needed. Taking cetirizine as a long-term management strategy can help reduce symptoms over the course of seasons and years.

cetirizine hydrochloride is a well-established antihistamine medication commonly prescribed for the symptomatic relief of seasonal and perennial allergic rhinitis, skin allergies, and chronic hives. Its mechanism of action involves selectively blocking histamine H1 receptors. Cetirizine offers a favorable safety profile with mild side effects and low risk for drowsiness compared to older antihistamines. When taken as directed, it provides effective 24-hour relief of allergy symptoms for most patients.

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