The goal of this clinical trial is to learn whether a higher dose of cetirizine works better than the standard dose to relieve symptoms of acute urticaria (hives) in adults. The study also aims to learn about the safety of taking a higher dose for a short period of time. The main questions the study aims to answer are:

1. Does the higher dose of cetirizine help people with acute urticaria improve faster than the standard dose?
2. What side effects do participants experience when taking the higher dose?

Researchers will compare two groups:

one group taking the standard dose of cetirizine (10 mg per day) and another group taking a higher dose (40 mg per day). This will help researchers understand which dose works better and whether the higher dose is safe.

Participants will:

Take the assigned study medication for 7 days Record their daily symptoms, including itch and hive severity Return for follow-up visits on Day 3, Day 7, and Week 6 Have blood tests to check liver and kidney function before and after treatment

This study may help improve treatment options for people with acute urticaria and reduce the need for unnecessary steroid use.

This study is a randomized, parallel-group clinical trial designed to evaluate whether a higher dose of cetirizine provides better symptom relief than the standard dose in adults with acute urticaria. Acute urticaria often causes sudden wheals and intense itching that can significantly affect comfort and daily functioning. Although standard-dose second-generation antihistamines are recommended as first-line treatment, many people do not fully improve and are frequently prescribed systemic corticosteroids, which may lead to unnecessary side effects.

This trial investigates whether increasing the dose of cetirizine to 40 mg per day offers faster or more complete symptom improvement without increasing safety risks. Participants will be randomly assigned to receive either the standard dose or the higher dose for 7 days. The study uses a blinded outcome assessment to minimize bias. Symptom severity will be measured using validated tools, and participants will be monitored for side effects throughout the study.

Laboratory tests will be used to assess kidney and liver function before and after treatment. Follow-up visits will evaluate short-term changes in symptoms as well as the potential for recurrence or progression to chronic urticaria. The findings may help guide clinical decision-making and support more rational use of antihistamines while reducing reliance on corticosteroids in acute urticaria care.

Inclusion Criteria:

• Adults aged 18 to 60 years
• Clinical diagnosis of acute urticaria made by a physician
• Onset of new wheals within the past 24 hours
• Able and willing to comply with study procedures, complete symptom diaries, and attend follow-up visits
• Provides written informed consent prior to participation

Exclusion Criteria:

• Use of systemic corticosteroids within the past 5 days
• Use of immunosuppressive medications within the past 5 days
• Clinical signs of anaphylaxis, including respiratory distress, hypotension, abdominal pain, or acute laryngeal swelling
• Presence of angioedema without wheals
• Known diagnosis of chronic urticaria
• Known severe renal impairment (creatinine clearance <10 mL/min), heart failure (ejection fraction <40%), or hepatic failure
• Other skin conditions that may interfere with assessment (e.g., atopic dermatitis, eczema, bullous pemphigoid, AGEP)
• Use of ACE inhibitors or ARBs within the past 5 days
• Known allergy or hypersensitivity to cetirizine or components of the study medication
• Pregnancy or breastfeeding
• Known diabetes mellitus
• History of gastrointestinal ulcer disease
• Any condition that, in the investigator's judgment, would interfere with study participation or safety
• Declines to provide informed consent

Individual participant data (IPD) will not be shared because the dataset contains sensitive health information and the study sample size is small, making de-identification difficult. In addition, the informed consent form does not include permission for public sharing of individual-level data.