Cetirizine Dihydrochloride vs. Cetirizine Hydrochloride

What's the Difference?

Cetirizine Dihydrochloride and Cetirizine Hydrochloride are both antihistamine drugs used to treat allergies and relieve symptoms such as sneezing, itching, and runny nose. The main difference between the two is the form in which they are available. Cetirizine Dihydrochloride is commonly found in tablet or syrup form, while Cetirizine Hydrochloride is typically available as a tablet or oral solution. Both forms are equally effective in providing relief from allergy symptoms, and the choice between them usually depends on personal preference or the specific formulation prescribed by a healthcare professional.


AttributeCetirizine DihydrochlorideCetirizine Hydrochloride
Chemical FormulaC21H25ClN2O3 · 2HClC21H25ClN2O3 · HCl
Molecular Weight461.82 g/mol388.89 g/mol
Salt FormDihydrochlorideHydrochloride
SolubilitySoluble in waterSoluble in water
UsageAllergy relief, antihistamineAllergy relief, antihistamine
Brand NamesZyrtec, ReactineZyrtec, Reactine

Further Detail


Cetirizine is a widely used antihistamine medication that is commonly prescribed to relieve symptoms of allergies such as hay fever, hives, and allergic rhinitis. It belongs to the second-generation antihistamines, which are known for their non-sedating properties. Cetirizine is available in two different forms: cetirizine dihydrochloride and cetirizine hydrochloride. While both forms share similarities in terms of their effectiveness and safety, there are some notable differences between them that are worth exploring.

Chemical Composition

Cetirizine dihydrochloride and cetirizine hydrochloride differ in their chemical composition. Cetirizine dihydrochloride is the dihydrate form of cetirizine, meaning it contains two molecules of water in its structure. On the other hand, cetirizine hydrochloride is the hydrochloride salt form of cetirizine. The presence of water molecules in cetirizine dihydrochloride can affect its stability and solubility compared to cetirizine hydrochloride. However, both forms are equally effective in blocking the action of histamine, the chemical responsible for allergic reactions.


When it comes to pharmacokinetics, cetirizine dihydrochloride and cetirizine hydrochloride exhibit similar characteristics. Both forms are rapidly absorbed after oral administration, with peak plasma concentrations reached within approximately one hour. They are extensively metabolized in the liver and primarily eliminated through the kidneys. The half-life of cetirizine, regardless of its form, is around 8-10 hours in adults. This means that the effects of the medication can last for a significant duration, allowing for once-daily dosing in most cases.


Both cetirizine dihydrochloride and cetirizine hydrochloride are equally effective in relieving allergy symptoms. They work by blocking the H1 receptors, which are responsible for triggering allergic reactions. By inhibiting the action of histamine, cetirizine helps reduce symptoms such as sneezing, itching, runny nose, and watery eyes. Numerous clinical studies have demonstrated the efficacy of both forms of cetirizine in providing relief from allergic conditions. However, individual responses to the medication may vary, and it is always recommended to consult a healthcare professional for personalized advice.

Safety Profile

Both cetirizine dihydrochloride and cetirizine hydrochloride have a well-established safety profile. They are generally considered safe for most individuals when used as directed. However, like any medication, they may cause side effects in some people. The most commonly reported side effects include drowsiness, dry mouth, headache, and gastrointestinal disturbances. It is important to note that the incidence of sedation is generally low with second-generation antihistamines, including cetirizine. Nevertheless, individuals should exercise caution when engaging in activities that require mental alertness until they know how the medication affects them personally.

Formulations and Dosage

Cetirizine dihydrochloride and cetirizine hydrochloride are available in various formulations, including tablets, capsules, and oral solutions. The choice of formulation may depend on factors such as age, preference, and the severity of symptoms. The recommended dosage for both forms of cetirizine is typically 5-10 mg once daily for adults and children above the age of 12. However, dosages may vary for specific conditions or age groups, and it is essential to follow the instructions provided by a healthcare professional or the product label.

Availability and Brand Names

Cetirizine dihydrochloride and cetirizine hydrochloride are widely available over-the-counter and by prescription. They are marketed under various brand names by different pharmaceutical companies. Some common brand names for cetirizine dihydrochloride include Zyrtec, Reactine, and Cetrine, while cetirizine hydrochloride is commonly sold as Zyrtec, Aller-Tec, and Cetirizine HCl. It is important to note that the active ingredient, cetirizine, is the same in all these formulations, regardless of the salt form.


In conclusion, cetirizine dihydrochloride and cetirizine hydrochloride are two forms of the same antihistamine medication that are equally effective in relieving allergy symptoms. While they differ in their chemical composition, both forms exhibit similar pharmacokinetics and safety profiles. The choice between cetirizine dihydrochloride and cetirizine hydrochloride may depend on factors such as formulation availability and personal preference. Regardless of the form chosen, cetirizine remains a trusted option for managing allergies and providing relief from bothersome symptoms.

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