Histec (Cetirizine Dihydrochloride)

Histec is indicated for the temporary relief of symptoms associated with common allergic conditions.

• Allergic rhinitis (hay fever) presenting with nasal congestion, sneezing, itching and watery discharge.
• Seasonal allergic conjunctivitis causing eye itching, redness, tearing and swelling of the conjunctiva.
• Chronic idiopathic urticaria (hives) characterized by recurrent wheals and intense itching.
• Mild allergic skin reactions such as eczema flare‑ups or contact dermatitis with localized itching.
• Itching due to insect bites or other minor dermatologic irritations when other causes have been excluded.

• Cetirizine dihydrochloride acts as a selective peripheral H1‑receptor antagonist. By binding to the H1 histamine receptor on mast cells, basophils and other cells, it blocks histamine from triggering the intracellular signaling cascade that leads to vasodilation, increased vascular permeability and sensory nerve activation. The inhibition of histamine release and other inflammatory mediators reduces the physiological response that produces itching, swelling and nasal secretions.

Like all antihistamines, cetirizine may cause unwanted effects, most of which are mild and reversible.

Common

• Mild drowsiness or fatigue, especially at higher doses.
• Dry mouth or mild throat irritation.
• Headache, often transient.
• Nausea or mild gastrointestinal discomfort.

Serious

• Signs of an allergic reaction such as rash, swelling, or difficulty breathing.
• Rapid or irregular heartbeat, palpitations, or chest discomfort.

Before using Histec, consider the following precautions to ensure safe and appropriate use.

• Do not give to children younger than the age specified on the product label unless advised by a healthcare professional.
• Use with caution in patients with renal impairment; dose adjustment may be required.
• Sedation can occur; avoid operating machinery or driving if you feel drowsy.
• Pregnant or breastfeeding women should consult a healthcare provider before use.
• Individuals with known hypersensitivity to cetirizine or other piperazine derivatives should avoid this product.
• Alcohol and other central nervous system depressants may enhance sedative effects.

Cetirizine can interact with other medicines; some combinations should be avoided while others require monitoring.

Avoid

• Alcohol or other central nervous system depressants that may increase sedation.
• Monoamine oxidase inhibitors (MAOIs) used within the past 14 days, due to potential additive effects.
• Theophylline, as cetirizine may increase its plasma concentration.

Use with caution

• Antacids or other drugs that alter gastric pH, which could affect absorption.
• Medications that prolong the QT interval, such as certain antiarrhythmics.
• Concurrent use of other antihistamines, which may increase the risk of additive side effects.