From the Guidelines
For the treatment of chronic spontaneous urticaria (CSU), cetirizine can be taken at a maximum daily dose of 20-40 mg (2-4 tablets of 10 mg), divided into once or twice daily dosing, and fexofenadine can be taken at a maximum daily dose of 480 mg (four 120 mg tablets), typically divided into twice daily dosing, as supported by the latest guidelines 1. The management of CSU involves a stepwise approach, starting with standard-dosed second-generation antihistamines, and if necessary, increasing the dose up to 4-fold higher if the patient's symptoms are not completely controlled, as recommended in the latest update of the international urticaria guideline 1. When using cetirizine and fexofenadine, it is essential to monitor patients for side effects, such as drowsiness and headache, and to adjust the dose based on symptom control and individual patient needs. The use of higher than standard doses of antihistamines in CSU management is supported by the latest evidence, which suggests that these doses can be effective in controlling symptoms while minimizing the risk of adverse effects 1. In terms of specific dosing, cetirizine can be taken at a dose of 10 mg daily, and increased up to 20-40 mg daily if needed, while fexofenadine can be taken at a dose of 180 mg daily, and increased up to 480 mg daily if necessary, as part of a stepwise approach to treatment 1. It is crucial to note that the treatment of CSU should be individualized, and patients should be closely monitored for response to treatment and potential side effects, with adjustments made as needed to achieve optimal symptom control while minimizing the risk of adverse effects. The latest guidelines emphasize the importance of using an "as much as needed and as little as possible" approach, stepping up and stepping down treatment based on levels of disease control assessed with the UCT, to minimize treatment burden and assess patients for spontaneous remission 1.
From the Research
Treatment of Chronic Spontaneous Urticaria (CSU) with Antihistamines
- The first line of treatment for CSU is non-sedating antihistamines, with desloratadine 5 mg or levocetirizine 5 mg being commonly used options, which can be increased up to 4 times daily if necessary 2.
- Cetirizine 10 mg is also an option, and according to a Cochrane Systematic Review, cetirizine 10 mg daily can lead to complete suppression of urticaria in the short and intermediate term 3.
- Fexofenadine 120 mg is another option, and studies have shown that high doses of fexofenadine can produce a significant dose-dependent response and control urticaria in most patients 4.
Maximum Daily Doses and Frequencies
- For cetirizine, the maximum daily dose is not explicitly stated in the provided studies, but it is recommended to use up to 4-fold the licensed dose if control is not achieved 5.
- For fexofenadine, the maximum daily dose is also not explicitly stated, but studies have shown that high doses can be effective in controlling urticaria 4.
- It is essential to note that the quality and heterogeneity of the articles reviewed made it impossible to reach robust conclusions, and large-scale randomized clinical trials are needed to determine the optimal dosing regimens for these antihistamines 4.
Equivalent Doses
- The equivalent doses of cetirizine and fexofenadine are not directly comparable, but studies have shown that cetirizine 10 mg daily and fexofenadine 120 mg daily can be effective in controlling urticaria 3, 4.
- Levocetirizine 20 mg daily and desloratadine 20 mg daily have also been shown to be effective in controlling urticaria, and these doses can be used as a reference for determining the equivalent doses of cetirizine and fexofenadine 3.